Thursday, April 7, 2011

Space Warfare XIV: Things As They Ought To Be


At 100 kilometers per second, any object - be it a depleted-uranium slug, a carton of skim milk, or a throw pillow - packs kinetic energy equal to 5 gigajoules per kg, equivalent to 1195 kg of TNT, rather more than a ton of bang. In space the bang will be soundless, but it will still hurt.

(Someone in the back raises their hand to ask, '100 km/s relative to what?' For purpose of this discussion the answer is 'relative to whatever it hits.' And you should have figured that out on your own.)

This is the basis for kinetic weapons in space warfare. To regular readers of this blog it is no news; in particular I discussed kinetics in two segments of this series of posts. (Though the specific form of killer bus I described in the second post is a bad idea.)

I bring kinetics up again because they were long my weapon of preference for space warfare, for at least three distinct reasons, distinct in addressing different aspects of the overall problem:

1 - Missiles in space have effectively unlimited range, more than even Ravening Beams of Death.

2 - If you have the space technology to put large numbers of people in space, you pretty definitionally have the capability to throw lots of luggage, and throw it fast.

3 - There is reasonable scope for tactical maneuver in kinetics-dominant space combat, something that (it seems to me) is much harder to get in laser combat.

You may note that these three justifications are ranked by increasing meta-ness. The first is a general consequence of space speeds. The second hints at future history.

Any spacefaring society on a grand enough scale to have grand space battles has put generations or centuries of major effort into its overall space technology, whether its past has been peaceful or warlike. Long range lasers probably have more limited and mainly military applications. (Extensive use of laser propulsion does change this equation.) As a point of comparison, in the 19th century military technology tended to adopt new civil technologies, rather than being a primary driving force in itself.

The third point is most shamelessly meta. The people who fight wars are not concerned to make them interesting; that is only of concern to people inventing them in order to write about them.


Thus my picture of kinetic space warfare was kinetic in style as well as in weaponry. My starting point was the observation that if two ships are armed with similar-performance missiles, the more maneuverable ship has a crucial advantage. It can (at least in principle) maneuver to evade an enemy's missile, while the more sluggish enemy ship cannot quite evade its own missile.

Multi-ship tactics also look potentially complex - and therefore interesting. Ships maneuver like (3-D, vector) polo ponies to line up shots at opponents while avoiding the enemy's shots. The worst position a ship can be in is dynamically surrounded, so that a burn that carries it away from one enemy's missile envelope takes it right into another's.

The second worst position a ship can be in is to make a burn that accidentally carries it out of the fight at the point of decision, allowing the enemy to defeat its consorts in detail.

Lasers, in my vision, were purely secondary and defensive, intended for last ditch defense against incomings. There was a serious question in my mind whether a defensive laser armament was even worth carrying - the extra mass of a laser battery would mean reduced missile firepower, more sluggish performance, or both.

In this thumbnail description it sounds much like space fighters dogfighting, though the scale of the thing was such that battles would unfold over hours or days, even weeks.


I have not put any numbers to all this, except for the ones I gave at the very beginning, implying combat encounter speeds on order of 100 km/s. When I first came up with this image of space battles my assumptions were EXTREMELY operatic, as in photon drives with multi-g accelerations. Eventually I worked my way down to mere fusion torches in the low terawatt range.

A variety of holes, of various gauge, can be punched or burned through this vision of space combat, but it still represents one variation on the theme of what we all want for story purposes, Cool Space Battles.


I eventually abandoned this conception. Not because the propulsion was still operatic even in its later, more modest forms - any setting where you have space battles at all, other than near-Earth encounters in a primarily terrestrial war, is at least demi-operatic. But I came to suspect that the laser assumptions I was making were conservative out of all proportion to the propulsion assumption, yielding the equivalent of ships with gas turbine engines and smoothbore muzzle loaders.

By no means is that certain to be the case. Lasers and space propulsion are not inherently linked technologies (though under some assumptions they would be). And there is plenty of experience to show that battle performance of weapons often falls short of bench test performance, sometimes dramatically so. But I came to feel that it was special pleading to assume as much, and ended up with laserstars, as I have described them in prior installments of this series.

At some future point I might change my mind again.


Discuss. (Gentlemen, you can't fight in here! This is the War Room!)



The somewhat retro image is from Atomic Rockets - read also the discussion on the linked page.

416 comments:

1 – 200 of 416   Newer›   Newest»
Anonymous said...

Rick; Space Warfare (both fictional and real) probably will depend on such a number of asumptions that speculation about it could wrap your brain in knots. However, I think that you could perhaps lump it into a few broad stages.
1) there haven't been any space-bases armed conflict yet, so when it does happen, it is all experimental and even the most outragious ideas are persuded as everyone scrambles to create a viable space force.
2) armed conflict has happened, but only limited, and at a time when technology is in flux (think about air power doctrine just after WWI) and space powers are building space forces bases on both previous experiance and a lot of theory. Not everyone will go down the same path; some will use mixed weapons, some will stress lasers over kinetics, others kinetics over lasers; some will build huge particle beam weapons; all because they have interprited the 'lessions learned' differently.
3) space warfare has matured and standard forms of tactics, strategy, and weapons types and their employment have worked themselves out. This will last until a revolution in weapons, propulsion, sensors, or some other tech alters tactics or strategy.

Personally, I think that lasers will be close-in weapons for several decades, (or even a couple centuries) with kinetics (both ballistic and guided) being the primary long-range weapons. More exotic weapons (the Casaba Howitzer comes to mind), might suppliment or even replace what we refer to as 'conventional' space weapons.
As to tactics; fly-by interceptions and orbital combat will probably dominate for decades, if not centuries. Strategy will be biased toward orbital bombardment and/or the capture or destruction of orbital/asteroid/ minor outposts.
To successfully invade a nation, you need a 3 - 1 ratio of attackers to defenders, and then you need to have an occuping force at least 0.5% to 2% of the conqured population. So North Korea isn't going to invade Callisto in the 2170's, nor is a nation on Mars going to invade China in the early 22nd century.
They might shoot the hell out of each other's space forces but invasion probably isn't in the cards.

Ferrell

Milo said...

My bias is that the more weapons the better. Battles are more fun when you have multiple different weapons, either creating multiple ship classes or a single ship with more than one weapon type (or both, of course!), which each have different tactical uses.



Rick:

"In space the bang will be soundless, but it will still hurt."

Wouldn't the ship that got hit still hear a sound, transmitted through their hull?

Assuming there's enough of them left to still be able to hear anything, that is.


"Long range lasers probably have more limited and mainly military applications."

Communications lasers?

Not that those need anywhere near the power of weapon lasers, of course.


"The third point is most shamelessly meta. The people who fight wars are not concerned to make them interesting;"

Seconded. So very much.

And this does extend to Burnside's Law values of "interesting", too.

KraKon said...

I did manage to combine powerful (GW range) lasers with a kinetics dominated battlefield...all within minutes range of each other.
What I did was use the lasers to propulse missiles using magnetically-contained laser thermal drives. Since the ranges are within 5000km, there is no need for the missile to have onboard sensors or any of the such-therefore it can fully profit from 100MN of thrust.
To reduce the lasers to merely propulsive mechanisms, I used a simple mechanism who's effectiveness was hammered into me in sfconsim-l:spinning. The ships have carbon shields spun to a relative-to-target velocity of 40m/s, reducing their effectiveness to 1/1666 of their supposed penetration depth.
You can spin the missiles up to 100's of m/s because they're essentially inert.
Make sure your setting doesn't allow for thousand meter long x-ray producing lineacs, but mere 100nm beams with solid state lasers, and you have ensured that damage is lowered to millimeter-per-second scales at 4000km.

For extra fun, give the ships nuclear pulse propulsion (mag-orion but without the 2km magnetic loop), so they are capable of half-g accelerations during combat, and the ability to change setting radically (earth to jupiter in 4 months.

Details are spread out on the LTAWS thread on sfconsim-l.

Rick-Thanks for the two Space warfare posts right after each other. My original vision was to have coilguns spawn hypervelocity rounds in a kinetic-dominated-what-the-heck-are-lasers battlefield...but I had to change for the same of plausibility.

Ferrel-
"More exotic weapons (the Casaba Howitzer comes to mind)"

I'm sure that will come sooner than later in you have nuclear pulse propulsion...too bad the range is too pitiful for it to be considered anything other than the usual (but more than expensive) kinetics round until a few hundred meters from target...

Anonymous said...

(SA Phil)

You could use some kind of phlebotinium lever to force this more interesting type of combat to come to pass.

Invent an effective Laser plot armor- so that Laserstar's lose their Luster

It could be anything:
-Some undiscovered concept that would limit Laser's effective range severely. Essentially chop them down the the range of the plot.
-A superalloy variant that is very good at diffusing Laser's destructive potential.
-Reducing Laser's efficiency to the point their heat build up is ridiculous. (This is very near the case anyway. But the Nuke Electric drive has the same problem.)

============
I think even slower speeds could be very interesting. The slower the ship's closing speeds the more combat maneuvers/ serious vector changes they can make when they are in range of each other. And the longer the encounter time.

And the more impressive rail-guns / light gas guns / Metal-storm etc are.

A missile concept I had was a 100kg missile that is launched from a light gas gun That in turn has a Gatling Shotgun as its standoff weapon.

Depending on the closing velocities it would either have impressive maneuver on its own, or at least an ability to be a steered bullet. And then since it is a standoff weapon it points itself at the enemy ship and dakkas away.

==========
Additionally a drive system wastes its heat out the back of the ship (Nuke Thermal / NSWR? / AM Water /Plasma?) Making for much smaller radiators could add further changes in how things would develop.

Without massive radiators and giant powerplants, Kinetics make a lot more sense due to power constraints.

And you get a lot more thrust with those, leading to a more frantic manuever enviroment.

Marcel said...

Hello Rick,
first off I would like to say that I really appreciated reading your blog (what I do for more than half a year now), since you elaborate on a lot of quite interesting ideas concerning the plausible mid future and especially spaceflight in this scenario. This is pretty much like reading a good science fiction without all these pesky plot devices made up by the author in order to get a coherent and interesting story - or what he thinks is one. So thank you.

Here imho the misconception starts with the idea that continuous beam lasers would be used as weapons. This will not be the case (at least not in space battles in the mid future), since they have weaker armour penetration, do less damage after they penetrated the armour and can be more easily defended by reflective coating and active cooling of the target ships hull than a pulsed laser with the same energy.

Regarding armour penetration:
You can easily calculate that continuous beam lasers are inferior in penetration by using this calculator: http://panoptesv.com/SciFi/DeathRay.html. Simply try calculating the penetration of a 1 MJ pulse and of a 1MW continuous beam in one second for 1 cm spot size for a material of your choice. Apart from that I think it is immediately apparent that pushing material away requires less energy than vaporising it what means to break every chemical bond in the given volume.

Regarding damage after penetrating the armour:
While a continuous beam will vaporise everything in its direct beam path the damage to the surroundings is pretty much limited to scorching and setting on fire things in its immediate vicinity while a pulsed laser blows up everything it touches, generating shock waves and making high velocity shrapnel fly all over the place.
To put it more imaginative simply imagine standing behind an armour plate while it is cut by a blowtorch or being blasted apart by a high explosive charge.

Too large so I need to split.

Marcel said...

Here imho the misconception starts with the idea that continuous beam lasers would be used as weapons. This will not be the case (at least not in space battles in the mid future), since they have weaker armour penetration, do less damage after they penetrated the armour and can be more easily defended by reflective coating and active cooling of the target ships hull than a pulsed laser with the same energy.

Regarding armour penetration:
You can easily calculate that continuous beam lasers are inferior in penetration by using this calculator: http://panoptesv.com/SciFi/DeathRay.html. Simply try calculating the penetration of a 1 MJ pulse and of a 1MW continuous beam in one second for 1 cm spot size for a material of your choice. Apart from that I think it is immediately apparent that pushing material away requires less energy than vaporising it what means to break every chemical bond in the given volume.

Regarding damage after penetrating the armour:
While a continuous beam will vaporise everything in its direct beam path the damage to the surroundings is pretty much limited to scorching and setting on fire things in its immediate vicinity while a pulsed laser blows up everything it touches, generating shock waves and making high velocity shrapnel fly all over the place.
To put it more imaginative simply imagine standing behind an armour plate while it is cut by a blowtorch or being blasted apart by a high explosive charge.

Regarding susceptibility to defence:
While a pulsed laser widely ignores reflexivity of the surface, cooling and relative movement of the target a continuous ray laser can, dependent on its intensity, easily be defended by each of these factors or a combination of them.

Need to split.

Marcel said...

To cut a long story short I think if you consider the use of pulsed lasers (blaster type) and make them quite large - say a pulse in the gigajoule range every few seconds through an aperture (probably mirror) several 10 m in diameter - you have a weapon which can deliver the equivalent of a ton of TNT over light second ranges every few seconds. And I don't see the point especially if you consider installations like the laser megajoule and the National ignition facility why we couldn't start building something like this tomorrow (literally) if we choose to make the investment (probably several trillion (10^12) dollars) as an orbital or fixed installation (perhaps Luke can correct me here?). If you build two of them in geosynchronous orbit nothing short of a laser star with a similar laser (which would be pretty science-fictional), and definitely no kinetic bus and no nuclear warhead, no material object at all short of a relativistic and I mean really relativistic (0.1c won't do the trick if it's not really large - say 10 metric tons and above) kinetic kill vehicle will ever touch the Earth or these orbital installations. This of course goes for any other point in space which I choose to defend. Perhaps a slightly smaller laser star or a missile with a bomb pumped laser with a laser range of several 10,000 km would do it if it has a closing velocity of several hundred kilometres per second and the ability to jinx with an acceleration in the order of 100 m/s² to exploit light speed lag. But these options would also be pretty science fictional. The whole thing gets a lot worse for the attacker if you allow for X-ray lasers and get a range in the light minutes.
So in my opinion your tech level has to outclass the defenders by several orders of magnitude because a reasonable large laser can only be defeated by larger one. And the attacker has to move it over at least interplanetary distances while the defender can build it on the site and use stationary power generation and heat sinks of arbitrary size.

ElAntonius said...

One thing that comes to mind is that societal pressures often direct the path of warfare far more than technology does.

In the Vietnam war era, the F-4 Phantom was created to fight the war that technology told us would happen: it was a high speed interceptor with long range missiles, designed to intercept incoming bombers and return to base.

So then we get on to a politically complex Vietnam war, and for fear of igniting a "real" war with the Communist bloc the American government handcuffs the pilots; forcing engagements within visual range where the F-4 was ill equipped to operate. Had the F-4 been allowed to play to its strengths, it likely would have been far more dominant in that theater.

The last gun kill (IIRC) made by an airplane against another aircraft was by an A-10 against an Iraqi helicopter in the first Gulf War...that's a close air support craft killing another close air support craft with a close air support weapon.

My whole point is that while technology trends may dictate what is possible, there are far more factors involved than just technology in terms of what is used.

Because laserstar combat is so reductive (assuming rough parity in technology, it reduces to a game of who outnumbers who with a large proclivity for Pyrrhic victory) it might become much like the space equivalent of nuclear warfare: the involved powers build for it, but no one actually fights it because there are no winners (of course, no one can stop building for it because an overwhelming technological or numerical advantage does result in a winner).

The irony would be that everyone has billions invested in a space fleet that does nothing except look scary on station keeping orbits while little manned gunboats with comparative pea shooters do the actual fighting over far more localized things.

Anonymous said...

(SA Phil)

Marcel,

Isn't a GW / Light Second Range pulse-laser Laserstar still essentially a Laserstar?

Marcel said...

Yes, if you want but if it is mobile (what I would consider a laser star), so that it can be used for attacks it would be utterly operatic or even outright handwavium, if stationary it could be build today.

Anonymous said...

(SA Phil)

The way I interpreted the Blog-post scenario is that Rick was imagining a combat environment with no Laserstars

Or at least one where Laserstar's were handicapped in some way allowing for a more interesting kinetic (both weapons and ship movements) environment.

Although you may have hit on something there -- If truly effective lasers could not plausibly work as a mobile platform; it would severely curtail their dominance.

At least out beyond their effective range.

Still a light second is quite far and the giant invincible ground laser would rule a lot of potentially interesting scenarios.

Anonymous said...

(SA Phil)

Rule *Out* a lot of potentially interesting scenarios that is.

If you have the equivalent of a god-mode anti aircraft/spacecraft/missile laser with a light second range

It means all the kinetically chaotic stuff would take place beyond one light second.

Of course its also much easier to make relativistic kinetic strikes on a stationary weapon.

ElAntonius said...

I'd say stationary defense lasers actually rule *in* a lot of good scenarios, by pushing conflicts out to relative backwaters.

We've discussed the "dominance of Earth" trope before, and by making Earth and other "home bases" invincible fortified positions with massive laser arrays, we can actually push some opera tropes, because we can force colonies to fight with what they got instead of what they'd like to have.

Lentulus said...

One thing that comes to mind is that societal pressures often direct the path of warfare far more than technology does.

I think that is an excellent point; and societal pressure, as you pointed out, includes pressure from specialists who are certain they know what technology will be for the next war. Sometimes (like naval combat technology at the start of WWI) the waring parties have been drinking the same cool-aid and come up with similar solutions. Sometimes (the sinking of the Price of Wales comes to mind) one group of technology advocates is in for a nasty surprise.

The collision of iron, coal and rifled guns in the late 19th century is a fascinating period, and I would expect a similar diversity of design and expectation the first time a society finds itself trying to prepare for war in space.

Aside of Arthur C Clarke's "Superiority" I am not aware of any science fiction that addresses this sort of issue.

jollyreaper said...

test

jollyreaper said...

Because laserstar combat is so reductive (assuming rough parity in technology, it reduces to a game of who outnumbers who with a large proclivity for Pyrrhic victory) it might become much like the space equivalent of nuclear warfare: the involved powers build for it, but no one actually fights it because there are no winners (of course, no one can stop building for it because an overwhelming technological or numerical advantage does result in a winner).


And it also does make you wonder what the typical fighting would be over -- scuffle over the territory or a fight for the very survival of the nation.

Depending on how vulnerable the planets are, it could be a multi-sided cold war situation. The major powers all have home planets you don't touch for fear of setting off the Big War but all the proxy territories are fair game.

There was never any chance of the USSR actually invading the US, despite fears to the contrary. How could they hope to hold the country? They had more than enough headache just administering their own territory. The last serious wars of conquest were fought in WWII and I think it would have been very interesting (in the chinese sense) to see the Axis victory scenario and whether or not they could really hold onto those conquests. I don't think so.

The real question in the setting is going to be whether there are limited resources. Is there a zero-sum economic game going on? If there's plenty of room for everyone, then the potential for war is going to be more about ideology than greed. Is the other side doing something so heinous that you can't allow them to persist in it?

As a hypothetical example, the Kzin from the Man-Kzin Wars genetically engineered their females to become sub-sentient. I saw a variation of this in a scifi story where a post-nuclear holocaust theocracy with a strong Islamic flair devised a doctrine of perpetual virginity. Women on their wedding day are given a Memento-style treatment that fries their ability to lay down long-term memories. Each day they wake up their last memories will be of visiting the marriage clinic. They have a book they read every morning that tells them who they are, who their husband is, and whatever information he deems relevant. It makes foot-binding and genital mutilation seem kind in comparison.

Anyway, something like that could well be enough to kick off an ideological war.

Stross had a great idea in his novel Glasshouse, the Censorship War. The idea is that interstellar civilization uses wormholes and assembler gates that can store mental maps of humans as backups and reconstruct bodies from scratch. What happens when someone creates a censorship virus to redact knowledge from the minds of the uploads? People aren't even sure who they're fighting against because they don't know what they've forgotten. That's a kick-ass scifi problem because it presents a serious human conflict that wouldn't have even been possible within the intellectual confines of 19th and 20th century thinking but, given the posited technology, you can totally see happening.

Thucydides said...

Ben Bova's book "Millenium" had a bit of this (although the bulk of the book was the political cut and thrust at home and on the Moon). As the US and USSR built ABM laser satellites in orbit, astronauts would try to identify the weapons among the decoys and disable them with hand grenades launched from a spring launcher (something like a WWII "PIAT").

When a grenade damaged a mirror or sensor assembly, the satellite was off line. (An unstated assumption in the story is it seems to be more economical to build new satellites rather than recover old ones. Since the satellite war and ABM shield in general is a semi secret operation, this may be to preserve secrecy from the general public).

The astronauts in this scenario were essentially strapped to a "broomstick" rather than flying into battle in a LEM Warrior, so Rick's meta assumption about orbital battles being fought in clutter with very low powered weapons works out here.

Scott said...

I have always assumed a range of weapons on any combat spacecraft.

Lasers and kinetics, both gun-rounds and 'fish' like modern torpedos.

Raymond said...

Following.

Rick said...

Welcome to a new commenter!

On pulse versus CW lasers, this strikes me as important to actual design, but mostly invisible in human terms, since a pulse laser probably is in the kHz range at least.

A simple way to get rid of laser stars, in any given setting, is simply to assume that one of the technical strictures that Tony argued in the last comment thread is how things play out. Difficulty in holding a very high power precisely on target could easily degrade range performance by an order of magnitude or more.

And it is easy for me to believe that most of the interesting action won't involve massive battle constellations, but center on small patrol forces and such.

Tony said...

Scott:

"I have always assumed a range of weapons on any combat spacecraft.

Lasers and kinetics, both gun-rounds and 'fish' like modern torpedos."


I would presume:

A missile capability that could carry out at least smart kinetic, high explosive, and nuclear attacks. (This might actually require a couple of different missile types.)

The capability to use the vessel as a launch vehicle for ballistic attacks: smart kinetic, dumb kinetic, high explosive, and nuclear.

A point defense capability. I'm agnostic about lasers, guns, missiles, or any combination, as long as it's reasonably effective.

I would also expect a larger fleet to have several optimized classes:

Ballistic "bomber" (lots of ballistic weapons, point defense)

Strike fighter (lots of missiles and guns, point defense)

Escort (long range counter-missile missiles, point defense)

You could possibly combine the strike fighter and bomber into the same class, depending on the flexibility of weapon mounts.

Charles said...

I agree with this because the real fun of a sci-fi battle is playing around with the pieces you want. In my setting kinetics are the major weapon systems both in the form of missiles (light gas or chemfuel, guided or dumb, KE warhead), railshot (mostly dumb missiles launched from railguns), and point defense cannons shooting 25-40mm explosive or flak rounds.

LASER beams quite frankly are not as interesting to write about as big cannons duking it out in the depths of space.

Tony said...

Charles:

"...big cannons duking it out in the depths of space."

I'm not convinced there would be much of anything duking out in the depths of space. I would think the first strike would be a saturation ballistic kinetic attack, followed by mopup of whatever defensive forces were left in the orbitals.

jollyreaper said...


I'm not convinced there would be much of anything duking out in the depths of space. I would think the first strike would be a saturation ballistic kinetic attack, followed by mopup of whatever defensive forces were left in the orbitals.


That really does seem to have the right feel. The closest the attacker gets is watching the blips from millions of miles away, the closest manned defenders get to this is from bunkers buried deep somewhere safe.

Do you think the dynamics would really change drastically based on whether the combatants are native to the system as opposed to being from another system?

I think it would really change the flavor of the fight, even with the same technology. I've yet to see anything to convince me that a planet isn't a giant liability waiting to get whacked by someone with superior firepower. Space habs would sit in the same category. If both powers have their whole civilization in one system, balance of terror. You whack his home, he whacks yours, so you keep it civil. Invader comes from outside, he's got less of an industrial base to draw on but no home system to whack (at least within the immediate tactical discussion.)

jollyreaper said...

In Iron Sunrise, Stross has FTL but also has a MAD insurance policy -- r-bomber retaliation fleets. If the government of a polity is destroyed, the retaliation fleet launches on their designated targets. They're Killing Star-style relativistic bombers, .9c with hundreds of sub-munitions a piece. Given his tech, they're hard to detect when under thrust and coast invisibly once the burn is complete. (arguments can be had as to whether this is likely.) They remain pretty much invisible until they're too close to the target to do anything about. The existence of such weapons is why empire-building is supposed to be impossible.

Now if FTL is expensive, then we could run into a situation where it's expensive to project power and it's not a guarantee that the attacker will have complete superiority when he gets there, thus advantage of defense remains very high. A power confined to a single system might still put up a hell of a defense against an interstellar foe, even if they can't reliably strike back against the foe's home system.

Anonymous said...

KraKon: As to Casaba Howitzers, I was under the impression that the effective range was closer to several hundred to a couple of thousand kilometers, but I will have to do some more research to confirm that; I'll get back to you on that.
Anyway, it might be that you'd have massive battle stations orbiting heavily populated worlds, smaller mobile armmed logistics bases orbiting in the vicinity of lesser human populations, with small interceptors, convoy escorts, and interdiction vessels being the bulk of any nation's space force. Throw in some specialized ships for importaint-but-not-everyday-missions and you've got the makings of some space opera.
Of course, writting a story of everyone in the solar system scrambling to create a space force from scratch due to Callisto and Ganymeade colonies fighting over Europa might also be interesting...

Ferrell

Thucydides said...

I wonder about the cost effectiveness of this all. A laserstar, or ground mounted laser with fighing mirrors in orbit will be a very large expense, but as Rick calculated in one of the space war threads, a SFnal ravening beam of death needs to be swarmed with over 1000 KKV's in order to ensure its saturation and destruction. This will also be a big slice of any nation, colony or even system's resources (especially if each side can keep up production. If one side unilaterally gives p due to resource exhaustion or civilian tax revolt, then the other side wins pretty much by default).

Given that lasers are high precision, high tech items, there may be a certain edge for the KKV's to be churned out in a "Willow Run" type assembly line. The laser needs to be easily scaleable or capable of rapid upgrades to keep pace. More modules are possible, but since as I understand it the true key is the optical train it seems a bit of a stretch for the laser's primary mirror to be quickly doubled in size to increase the effective range or sensor resolution (barring a dramatic revolution in manufacturing tech. Even then, KKV production will probably scale at the same rate).

Luke said...

Rick:

Eventually I worked my way down to mere fusion torches in the low terawatt range.

and

Lasers and space propulsion are not inherently linked technologies (though under some assumptions they would be).

I will just throw out that the most plausible way to get terawatt fusion torches is with laser compression and ignition, which leads you to laser powers of at least 1% of your power output - and that's just for D-T fusion. Go to something with more energy remaining in the plasma, and you probably need lasers an order of magnitude more powerful.

Using small specks of antimatter for fast ignition of the fusion pellets might save you an additional factor of ten or so in laser power, but you still need the laser compression.

If you go with alternate driver beams (heavy ion beams are plausible, for example), then you end up with high power particle beams that can be rapidly and tightly focused instead.

Anonymous said...

(SA Phil)

If perhaps targeting was not sophisticated enough to get direct hits on the relatively tiny spacecraft beyond 1000 km (even the Nimitz is tiny from 1000km)

The at closing speeds of 100 kms as Rick suggested would definitely push things towards kinetics - since the weapons would only take 10 seconds to cross that gap. (discounting the range diminishing during that time)

It would take a lot less of a swarm to get through, possible as few as two missiles, or even one with luck.

So a lot of it would depend on the Laser's effective range. Even if it could demolish another warship at 1 light-second it need not (for the sake of story) be able to score hits at 1 light second.

A bit like large battleship guns before radar targeting.

If you have myopic targeting for direct fire weapons, Missiles then rule the day.

Ships with fast accelerations such as drones could also then have more value, racing against the targeting solution clock.

I expect you could tailor the setting to have the targeting match the desired encounter pacing. Adjusting effective ranges and closing speeds accordingly.

--------
I don't expect we actually know how small a target a Laser Weapon is going to be able to effectively hit at ranges much beyond our current experience?

Or perhaps I am being overly naive and we do know. Rendering the whole thing a implausible construct.

Although perhaps not as "soft" a construct as deflector shields and swooping fighters.

Rick said...

Marcel -

This is pretty much like reading a good science fiction without all these pesky plot devices made up by the author in order to get a coherent and interesting story - or what he thinks is one. So thank you.

A belated LOL - you have outed one of the secrets of this blog. Techno-geekery is (let's face it) fun, but it does not go well with stories. In fact, a good story tends to push all the cool tech stuff into the background.

I found that out first hand. I also have an interest in 16th century naval warfare, but when I tried my hand at a historical fantasy novel with an appropriate setting it turned out to be a coming-of-age story about teenage princess Catherine de Guienne. In a story, Gloriana trumps galleases.

Rick said...

Luke -

I will just throw out that the most plausible way to get terawatt fusion torches is with laser compression and ignition

This is the 'some conditions' under which laser and drive technology are linked.

But I've pretty much concluded that for torch or even demi-torch level performance you need to incorporate an array of oscillating hands.

Of course a similar array can probably be fitted to your weapon lasers.


Regarding the rest of the discussion, for now I will sit back and enjoy ...

Carry on!

Milo said...

Jollyreaper:

"I've yet to see anything to convince me that a planet isn't a giant liability waiting to get whacked by someone with superior firepower."

Here ya go. Satisfied?

jollyreaper said...

@Milo
Concerning planetary vulnerability . . .

Given the parameters Rick sketched out targeting planetside could prove tricky but I was thinking more in terms of planet-busters. By analogy, street-fighting is awful, bloody business and an invading army would get chewed up but that's if they try and take the city. Dropping a nuke, on the other hand, is easy.

I would think taking a planet by force would be incredibly challenging. We tend to think in terms of d-day in space like warhammer 40k but what about sheer obliteration? If the planet is the soul source of mcguffin and you need to take it intact, there's a challenge. If you have your own mcguffin and seek to deny it to the enemy, it's time to start chucking rocks. And that's the defense I have a hard time conceiving of. How do you defend? It seems very analagous to nuclear war -- the only defense is preventing the war from happening. You can't trust on winning by force, you can't intercept the warheads or trust you'll catch every launcher. What kind of lasers would it take to defend against hundreds of r-bombs coming in? Planets just seem so vulnerable when talking about total, genocidal war.

Teleros said...

But I came to suspect that the laser assumptions I was making were conservative out of all proportion to the propulsion assumption, yielding the equivalent of ships with gas turbine engines and smoothbore muzzle loaders.

By no means is that certain to be the case. Lasers and space propulsion are not inherently linked technologies (though under some assumptions they would be). And there is plenty of experience to show that battle performance of weapons often falls short of bench test performance, sometimes dramatically so. But I came to feel that it was special pleading to assume as much, and ended up with laserstars, as I have described them in prior installments of this series.


Hmm. Thinking about it from the standpoint of someone on the war planning board, you really will want both kinetics & lasers. Consider: lasers are going to be more accurate than kinetics, and they have other uses besides blowing up enemy ships: communications, mining, point defence, just for starters. Thus, you can reasonably assume that there will a decent amount of research involved in improving lasers. Furthermore, some of the research on another type of laser will be of help (directly or indirectly) with ship-killing lasers somewhere along the line.

So:

1. They're more accurate than any missile, let alone unguided railgun slug (well, unless you've built a railgun that fires its slugs at .9c, but let's stick to hard sci-fi...).
2. The only reliable defence is armour (okay and shields if you got more soft sci-fi stuff, but let's not go there).
3. They are better suited for short bursts of action, whereas kinetics are better suited for longer engagements. Ie, waste heat vs ammo capacity. At least unless we're talking massive heat sinks (think asteroids etc).
4. Compared to kinetics, they're short-ranged.
5. There being no stealth in space, it is theoretically possible (barring FTL sensors) to use laser weapons in a massive pre-emptive "Pearl Harbour" (or Copenhagen, given that we all know space is an age-of-sail ocean ;) ) strike that ensures you win the war said strike has just begun. You can try the same with missiles / railgun slugs, but they're far more likely to be detected.
6. You can use ship-killing lasers for point defence too. Not ideal of course, but still possible.

In addition, people have always preferred weapons that do the job quickly: all things being equal, you pick the weapon that leaves the other guy less time to react (see #3).

Teleros said...

Now consider that historically, people have always tried to improve weapon ranges. We went from smoothbore cannons to rifled cannons, and now have (compared to the battleships of the past) practically unarmed warships called aircraft carriers that launch fighters that launch missiles at targets thousands of miles away from the carrier itself.

There are 3 ways, as I see it, to do this with lasers:

1. Put the laser on a delivery vehicle - think bomb-pumped X-ray laser missiles, or similar one-shot drone platforms.
2. Use a different wavelength more suited to long-range fire. Even if due to the various trade-offs this takes long enough that the other guy can launch a missile salvo at you (or blister your paint with his shorter-ranged lasers), I'd feel safer knowing that that's all I'll be facing.
3. Make it big enough that either (a) only a fraction of the beam's total power is needed to nail the target, or (b) the target gets hit by so many smaller beams that it's the same as one big one.


The point of all this is that people are going to want lasers, so you need to come up with a semi-plausible explanation as to why they aren't as common as they otherwise might be expected to be. For example:

1. A very effective armour against them. It's less good against kinetic weapons though (too brittle perhaps?), and too heavy to mount on missiles (so point defence still works).
2. Decent laser efficiencies just haven't been cracked yet. A ship can handle some point defence lasers (and perhaps they're even very good & accurate), but it just can't handle the waste heat from the big guns, so kinetics are preferred. There's even been research into "flak"-style point defence to further cut down on waste heat.
3. Treaties than ban the use of high-energy lasers, perhaps on the basis that you can at least warn people in the way of an out-of-control missile, unlike a laser. Expect the treaty to be thrown out if either one side figures it can get away with it, or if it's a war of annihilation.
4. Poor targeting systems. This seems rather odd to me (wouldn't people actively be investing in decent targeting systems? and why do they suck anyway?), but I suppose bears mentioning too.

There are plenty more of course, but hopefully that's good food for thought for now :) .



@Ferrell: "Of course, writting a story of everyone in the solar system scrambling to create a space force from scratch due to Callisto and Ganymeade colonies fighting over Europa might also be interesting..."

Indeed, especially if the first thought of the Jovian moon powers is to rush more reinforcements to the surface of Europa. You go from freighter / troop transport production to wanting to intercept the other side's transports, to wanting to stop their interceptors... thus begins the in-war arms race.

Teleros said...

Sodding thing ate the *first* half of my post. Here it is again, read *before* the above please :P .

But I came to suspect that the laser assumptions I was making were conservative out of all proportion to the propulsion assumption, yielding the equivalent of ships with gas turbine engines and smoothbore muzzle loaders.

By no means is that certain to be the case. Lasers and space propulsion are not inherently linked technologies (though under some assumptions they would be). And there is plenty of experience to show that battle performance of weapons often falls short of bench test performance, sometimes dramatically so. But I came to feel that it was special pleading to assume as much, and ended up with laserstars, as I have described them in prior installments of this series.


Hmm. Thinking about it from the standpoint of someone on the war planning board, you really will want both kinetics & lasers. Consider: lasers are going to be more accurate than kinetics, and they have other uses besides blowing up enemy ships: communications, mining, point defence, just for starters. Thus, you can reasonably assume that there will a decent amount of research involved in improving lasers. Furthermore, some of the research on another type of laser will be of help (directly or indirectly) with ship-killing lasers somewhere along the line.

So:

1. They're more accurate than any missile, let alone unguided railgun slug (well, unless you've built a railgun that fires its slugs at .9c, but let's stick to hard sci-fi...).
2. The only reliable defence is armour (okay and shields if you got more soft sci-fi stuff, but let's not go there).
3. They are better suited for short bursts of action, whereas kinetics are better suited for longer engagements. Ie, waste heat vs ammo capacity. At least unless we're talking massive heat sinks (think asteroids etc).
4. Compared to kinetics, they're short-ranged.
5. There being no stealth in space, it is theoretically possible (barring FTL sensors) to use laser weapons in a massive pre-emptive "Pearl Harbour" (or Copenhagen, given that we all know space is an age-of-sail ocean ;) ) strike that ensures you win the war said strike has just begun. You can try the same with missiles / railgun slugs, but they're far more likely to be detected.
6. You can use ship-killing lasers for point defence too. Not ideal of course, but still possible.

In addition, people have always preferred weapons that do the job quickly: all things being equal, you pick the weapon that leaves the other guy less time to react (see #3).

Citizen Joe said...

Lasers don't help against unguided kinetics. You might punch a few holes in the rock, but you're not altering its mass or course (significantly). What is worse is that you might be changing a big dodgeable object into hundreds of erratic undodgeable ones.

Lasers are only effective because ships have centralized elements that can be disrupted by a precision strike. If ships/missiles/etc. are not centralized, then you have to melt the whole thing into component molecules to stop it.

By contrast, throw a rock at it and the momentum transfers, altering its course.

Anonymous said...

I've been reducing the effectiveness of lasers via thermodynamics, myself - thermally conductive/ablative armor layers and realistic heat buildup, mostly.

Still working on it, to get it tuned just right, but the narrative trope of 'shielding at X%' has largely been replaced by 'point defenses at X% of heat capacity'.

Rick said...

Jollyreaper -

If you have your own mcguffin and seek to deny it to the enemy, it's time to start chucking rocks.

First a quibble. Kinetics (probably) have advantages over nukes in tactical space combat, but for slagging planets, dropping huge rocks on them is probably more work than just nuking the bejeezus out of them.

That said, I think your broader point is valid: Planets are exceedingly difficult to invade, but all too easy to simply smash. Thus something like MAD applies, making all-out war a very dubious instrument of power politics.

In human terms that is a feature, not a bug, but it is lousy for scenarios involving huge space armadas.

Teleros -

There is another way to increase the range of a laser, namely a bigger main telescope mirror. (Which is a major reason for my conception of laserstars.)

Citizen Joe -

As a tactical weapon, at least, unguided kinetics have limited effective range. And if the kinetic is a solid chunk, a flash-off burn on one side will impart a motion - nominally directly away from the laser, but in practice likely to have a lateral component.

Anonymous said...

(SA Phil)

Still it has to be hard to hit a bullet with a laser? Or perhaps not.

Possibly would depend on the size and range of the bullet.

And how long you have to line up the shot.

jollyreaper said...


First a quibble. Kinetics (probably) have advantages over nukes in tactical space combat, but for slagging planets, dropping huge rocks on them is probably more work than just nuking the bejeezus out of them.


I could go either way on this one. The most recent planet-smashing example from contemporary scifi is the destruction of the colonies in the BSG remake. They used nukes to get the bang. So, big rocks or nukes, which is cheaper? Really depends on the setting. In a Moon is a Harsh Mistress setting, giant rocks (converted grain barges) are far cheaper than nukes. But if you have to go FTL and launch the attack, the mass savings of nukes might be far cheaper than moving giant freaking rocks interstellar distances. YMMV.

That said, I think your broader point is valid: Planets are exceedingly difficult to invade, but all too easy to simply smash. Thus something like MAD applies, making all-out war a very dubious instrument of power politics.

Yup. And even going back into human history, land without peasants has little value. A mine without miners is worthless. A farm without farmers is worthless. If you can import your own colonists, that's great. If you don't have that surplus population, you really need a means of taking over the land without completely pissing off the locals.

Modern colonialism has been absolutely brilliant at that. The British Empire represented the high water mark of old school imperialism -- kick ass, occupy, extract wealth. New school colonialism is the American way -- assassinate democratically-elected leaders, insert friendly dictators, use free market justifications for extracting local wealth. Rather than the US supplying the soldiers, the local dictator is in charge of committing atrocities, hiring the muscle, and taking the blame. No ugly domestic press, no pictures of dead soldiers flown home, just a little tut-tutting about how awful things are overseas.

Scifi writers have been talking about the impossibility of cinematic interplanetary invasions for years. My first encounter with that was an old Stainless Steel Rat story. The most recent encounter was Charlie Stross' Iron Sunrise where the conventional wisdom is interstellar empires are impossible but the surprise is a group called the Remastered who have figured out a way to swing it. They use advanced technology to subvert people within the governments of their target worlds -- nanotech to puppetize people inside the governments. It's the brainwashing terror-fantasy of American Cold Warriors made plausible with futuretech. And given the existence of the technology, the strategy seems very workable.

jollyreaper said...

In human terms that is a feature, not a bug, but it is lousy for scenarios involving huge space armadas.


I wouldn't go so far as to say that. It means that places that aren't major homeworlds will remain in play even as the homeworlds are left untouched. You either have such a strong defense of these homeworlds (zillions of laserforts in orbit) that it becomes economically infeasible to mount an attack or all planets remain vulnerable and MAD dictates that nobody threatens them and everything remains proxy wars in the hinterlands. If things were otherwise then wars would be fought in short order and you would end up with a universal victor.

This falls into the Rise and Fall of Great Powers territory from Paul Kennedy. The idea is that without barriers to conquest, one strong idea will sweep through a region. Histories of Asia, the Middle East, etc support that premise. One power has their crap together, everyone else doesn't, they conquer all until internal contradictions weaken them and all falls apart. European geography, on the other hand, puts a HUGE premium on defense and massively penalizes conquest. Therefore, you get multiple strong, vibrant cultures in close proximity. Without those geographic barriers, conquest would have been easy and you'd quickly end up with monoculture. With those barriers, you have all these vibrant cultures in constant conflict but never able to attain ascendancy.

I think this is a point important enough that the possible permutations of what makes a planet important are serious enough to constitute entire genres of science fiction.

So in a space war sense, it's GREAT to have a Paul Kennedy situation. You have multiple combatants, competing cultures and ideas and mores, none of them have the power to wipe out the home planets of the other so they're only able to compete in the hinterlands.

If the gods of scifi gave me the funding to create the ultimate space opera for TV, the perfect solution would be to mine scifi for the greatest culture tropes available and place all of them in competition in a space opera setting with the caveat that the homeworlds would be too protected or it would be unspeakable for overt conquest or planet-smashing. You'd have your utopian society represented by your ecumenical Star Trek Federation. You'd have your 1984 police state culture. You'd have your asian-flavored warrior culture coming to terms with the rest of the galaxy. There would be the failed imperialists who used to be the galactic big cheese but are choking to death under the bloat of their own corruption. And of course there are the Extropians who are hated by all of the old powers because they represent a complete destruction of the old way of doing things -- would fit the mold of the anarchist or communist in the 19th/20th century way of looking at things. "People have a lot of money invested in the question of whether the answer is A, B, or C. You bastards are introducing a variable that ain't even in the roman character set! You're gonna ruin it for everyone!"

jollyreaper said...

As a general rule, I think it's entirely appropriate when trying to adapt a story from one medium to another, when people aren't familiar with the tropes, to make a pastiche of it. If telling scifi on television, it's perfectly valid to mine the best of literary scifi and incorporate those ideas into the new story. It's likely to be the first introduction the new audience will have to such ideas. Babylon 5 did this brilliantly. More recently, Heroes did this with comic books. Sadly, the first season was the only one that was any good. But the ideas that they brought in, anyone familiar with comics could say "Ah, they're referencing this or that" which is perfectly true. But the people coming to it as TV watchers rather than comic fans would not know this. They're given a nice survey of the best ideas from the genre without having to slog through all the awful, horrible bits everyone would like to forget.


This falls into the Rise and Fall of Great Powers territory from Paul Kennedy. The idea is that without barriers to conquest, one strong idea will sweep through a region. Histories of Asia, the Middle East, etc support that premise. One power has their crap together, everyone else doesn't, they conquer all until internal contradictions weaken them and all falls apart. European geography, on the other hand, puts a HUGE premium on defense and massively penalizes conquest. Therefore, you get multiple strong, vibrant cultures in close proximity. Without those geographic barriers, conquest would have been easy and you'd quickly end up with monoculture. With those barriers, you have all these vibrant cultures in constant conflict but never able to attain ascendancy.

I think this is a point important enough that the possible permutations of what makes a planet important are serious enough to constitute entire genres of science fiction.

So in a space war sense, it's GREAT to have a Paul Kennedy situation. You have multiple combatants, competing cultures and ideas and mores, none of them have the power to wipe out the home planets of the other so they're only able to compete in the hinterlands.

jollyreaper said...

If the gods of scifi gave me the funding to create the ultimate space opera for TV, the perfect solution would be to mine scifi for the greatest culture tropes available and place all of them in competition in a space opera setting with the caveat that the homeworlds would be too protected or it would be unspeakable for overt conquest or planet-smashing. You'd have your utopian society represented by your ecumenical Star Trek Federation. You'd have your 1984 police state culture. You'd have your asian-flavored warrior culture coming to terms with the rest of the galaxy. There would be the failed imperialists who used to be the galactic big cheese but are choking to death under the bloat of their own corruption. And of course there are the Extropians who are hated by all of the old powers because they represent a complete destruction of the old way of doing things -- would fit the mold of the anarchist or communist in the 19th/20th century way of looking at things. "People have a lot of money invested in the question of whether the answer is A, B, or C. You bastards are introducing a variable that ain't even in the roman character set! You're gonna ruin it for everyone!"

As a general rule, I think it's entirely appropriate when trying to adapt a story from one medium to another, when people aren't familiar with the tropes, to make a pastiche of it. If telling scifi on television, it's perfectly valid to mine the best of literary scifi and incorporate those ideas into the new story. It's likely to be the first introduction the new audience will have to such ideas. Babylon 5 did this brilliantly. More recently, Heroes did this with comic books. Sadly, the first season was the only one that was any good. But the ideas that they brought in, anyone familiar with comics could say "Ah, they're referencing this or that" which is perfectly true. But the people coming to it as TV watchers rather than comic fans would not know this. They're given a nice survey of the best ideas from the genre without having to slog through all the awful, horrible bits everyone would like to forget.

Anonymous said...

(SA Phil)

Okay so thinking on "fast kinetics" a bit. I have a concept I would like to run by everyone.

*Premise One- Space Elevator/Long Tether/Sky Hook technology of some sort exists.
*Premise Two- I can leverage that technology to Make a serious coil/quench gun.
*Premise Three- One of the biggest problems with coil guns is how to get substantial length without insane Mass/structural problems.

========


The ship itself would accelerate/be towed until it had a course that would take it to the battle zone on a flyby.

The ship would separate, connected by a tether, a Tether of mutiple cables that held/suported the magnetic coils, a bit like a suspension bridge.

This tether could be 5km, 10km, 100km -- whatever fits the limitations and the requirements.

The ship would be given a rotational spin- a bit like Zubrin's "artificial gravity" idea. This would make the tether taut.

So the vehicle/weapon looks like this:

XXX-0-0-0-0-0-0-0-0-0-XXX

The Cables/coils are now the Coil Gun. The Two ship haves have the normal ship components - and there is a hole in them for the "bullet" to fly through of course.

Now the ship will be able to fire every time it rotates to the right facing. If it were a clock it could fire every time it was 12 o'clock. Potentially it could shoot out either end, allowing it to shoot at 12 and 6 oclock.

The ship would be limited, so it would need escorts for point defense and all of that. It would be enitrely incapable of manuever during the conflict.

Of course to make up for that it could rain down kinetic death at 100, 200, 300 kms whatever is feasible.

Anonymous said...

(SA Phil)

I should say Almost entirely incapable of maneuver.

The ability of the ship to change its orientation would be based on the strength of the tether, it would need to be able to make adjustments for targeting reasons.

Anonymous said...

KraKon; apparently much of the data on the Cabasa-Howitzer is classified; however, I have figured out some theoritical stuff. For a device of ~4.76 kt yeald with a Lithium faceplate 1mm thick, and 100mm wide, you get a plasma pulse traveling at ~20%c, with a devergance of about .11 degrees. Because it is 85% effecent (85% of the total yeald is transfered to the plasma bolt), if the target surface is greater than the surface of the plasma pulse, it will hit with ~4 kt yeald. My math breaks down about now, so I'm not sure what the maximum effective range of the weapon is, but I'd think it would be 60000 km or less.

Luke said:"If you go with alternate driver beams (heavy ion beams are plausible, for example), then you end up with high power particle beams that can be rapidly and tightly focused instead."

So, would an array of fission-fragment rockets pointed at a jet of LiH at the input of a magnetic nozzle be a good (story-plusible) fusion rocket design?

Ferrell

Milo said...

Jollyreaper:

"Given the parameters Rick sketched out targeting planetside could prove tricky but I was thinking more in terms of planet-busters."

Planetbusters what now?

Talking about hitting a plausible midfuture civilization with a planetbuster is like talking about hitting a medieval castle with a nuke.



Teleros:

"4. Compared to kinetics, they're short-ranged."

Compared to missiles? Yes. Compared to unguided kinetics? No.

True, unguided kinetics can theoretically deal the same damage at any distance, while lasers fall off with the inverse square law. But kinetics' usable range will be limited by the distance at which you can reliably aim them and shoot them hard enough to not give the enemy time to dodge.


"5. There being no stealth in space, it is theoretically possible (barring FTL sensors) to use laser weapons in a massive pre-emptive "Pearl Harbour" strike"

Only if you're within laser range of the enemy. Unless your lasers have interplanetary ranges, it's going to be hard to get close without the enemy noticing you're acting shifty.



Jollyreaper:

"And even going back into human history, land without peasants has little value."

There are, however, scorched earth tactics. There are times when you don't care so much about acquiring land as you do about denying it to the enemy.

However, this is unlikely to happen in the plausible midfuture. In our solar system, there simply aren't enough planets (or moons) to be able to afford considering them expendable.

KraKon said...

"KraKon; apparently much of the data on the Cabasa-Howitzer is classified; however, I have figured out some theoritical stuff."

Your google-fu is superior to mine. All I used were rocketry equations...

"For a device of ~4.76 kt yeald"

Seems a bit high for a single pulse...suitable for weaponry but not for propulsion. For propulsion, I found out (the hard way, halfway through designing the ship) that several subkiloton (4.2 TJ yield) charges are better than a single large pulse per second (radiation flux, shielding, cooling issues and smoother accelerations allows for a lighter drive).
On the other hand...4.76kT yield should weigh no more than 100kg with Dr. Schilling's maximum, 20kg in my universe. Small, light and POWERFUL. Scary if a propulsive shaped charge could be converted easily into a nuclear skewer by changing the filler...

"with a Lithium faceplate 1mm thick, and 100mm wide, you get a plasma pulse traveling at ~20%c, with a devergance of about .11 degrees. Because it is 85% effecent (85% of the total yeald is transfered to the plasma bolt)"

Performance that blows my mind.
My calculations told me I could not capture more than 7-8% of the blast, and that the mean velocity of ions would be 1400km/s...
.2c would not be very helpful for a propulsive system. I calculate that my 20kT ship could not hope for more than milli-to-centigee performance.
I'm certain than the filler, instead of being lithium, could be replaced by a higher-Z material that not only requires less X-ray opaque beryllium (by being denser) but reduces exhaust velocity to useful levels (fraction g performance). Since I'm using superconducting mag-orion, iron should be fine in this role (and can double as armor, and has no tanking or propellant volume problems).


",if the target surface is greater than the surface of the plasma pulse, it will hit with ~4 kt yeald."

In other words, if the magnetic field has a diameter of 15m, it will capture 100% of the ions within 60m.
For weapons considerations, 0.11 degrees is not enough for skewering at looong distances.
At 100km, the surface intensity is 43.7kJ/m²...comparable to a millisecond pulse of a 53.36kW laser (100nm, 10m diameter), or 534MW micron laser.
At 1000km, the surface intensity falls to 437J/m², which is similar to...uselessness.

"My math breaks down about now, so I'm not sure what the maximum effective range of the weapon is, but I'd think it would be 60000 km or less."

This is a short range weapon...to be used at the ranges where frag missiles release their submunitions. Otherwise the plasma cloud disperses far too quickly, and is far less effective than lasers at ranges further than a few tens of km...but within that distance you can be sure it will punch through just about anything through and through.
Compare it to a particle beam weapon. Same damage mode (particle stream) but one releases lots more energy on a short distance, the other needs PeV performance to get the stuff to strike even at 2000km (assuming Sfnal efficiencies of 99.9999999%, yes count the 9's), compared to the above laser.

KraKon said...

More:
"So, would an array of fission-fragment rockets pointed at a jet of LiH at the input of a magnetic nozzle be a good (story-plusible) fusion rocket design?"

An electromagnetic method for accelerating the ions would be much lighter, cheaper (enriched uranium fuel cost), more efficient and gets the ions up to faster velocities (near c instead of a few 100km/s). Since the ions are pulsed, they're even better as an ignition method as FRR provides a continuous stream of ions.

Rick, have you ever considered an ORION future? I strongly recommend an upcoming post where ORION demitorches, instead of fragile milligee laserstars, rule the battlefield. You can also throw away the multimegawatt lasers since you don't have a direct propulsion-to-laser electrical supply anymore...

PS: No comment on LTAWS?

Luke said...

Ferrel:

So, would an array of fission-fragment rockets pointed at a jet of LiH at the input of a magnetic nozzle be a good (story-plusible) fusion rocket design?

It doesn't sound very plausible. You need very intense, focused, nanosecond or less pulses to get significant compression. A jet from a fission fragment reactor would not be very focused or sufficiently short (or, if made that short, would either not be sufficiently intense or would result in a fusion yield insignificant compared to what the fission reactor is putting out).

jollyreaper said...

When I say planetbuster I don't mean the death star blowing the place up. I mean something that wrecks the biosphere, end of life as we know it. You don't have to blow the whole thing up to do that, just chuck some dino killers.

Anonymous said...

(SA Phil)

I think nuclear missiles would be potentially far cheaper than "planet killer" rocks actually.

The planet killer rock requires some sort of propulsion that can handle a lot of mass. (high thrust)

But if you had a true plutonium economy you could mass produce nuclear warheads easily.

Its the lack of the plutonium economy, non-proliferation efforts, and specialization that make nuclear weapons expensive, not anything inherently expensive/intricate in the design.

Anonymous said...

(SA Phil)

Thinking on that, Nuclear "point defense" missiles(10's of km+ really)..

Would be pretty effective for protection against clouds of incoming kinetics.

Rick said...

I interpreted 'planet busting' the same way SA Phil does - basically genocide, not literally smashing the planet. There's a whole morbid argument about just how many gigatons it takes to terminate industrial civilization on a planet, but probably far, far less than even dino killer energy.


I am not a big fan of Orion, most basically because getting around space by deliberately nuking yourself thousands of times just generally strikes me as a Darwin Award approach to the problem.

There are some more specific challenges as well, from design of the shock absorbers to cost of the propellant. Bear in mind that you need more or less a critical mass of (expensive!) fissionable stuff to get any nuclear yield - subkiloton explosions are not 'cost efficient.'

Fuel supply security issues, too. :-)

Anonymous said...

(SA Phil)

I think that was jollyreaper but I also agree about the "planet buster".

Maybe even smaller than that. hundreds of rocks that impacted in the kiloton range would do wonders to softening up an enemy prior to an invasion. (in the brutal sense anyway)

---------------
On the same note as Orion might be the Nuclear Salt Water Rocket Concept.

If such a design were actually feasible it would be a massive amount of thrust. Although the idea of decelerating to attack a planet and sending massive amounts of radioactive materials its way seems a bit of a WMD prospect in and of itself.

Milo said...

Jollyreaper:

"When I say planetbuster I don't mean the death star blowing the place up. I mean something that wrecks the biosphere, end of life as we know it. You don't have to blow the whole thing up to do that, just chuck some dino killers."

Okay, like airdropping conventional bombs on a medieval castle, then.

Tsar Bomba, the largest nuclear weapon ever made: 50 megatons of TNT. (Could theoretically have gotten 100 megatons of TNT if they went all out.)

Dino killer meteor: 120 teratons of TNT (2.4 million Tsar Bombas).

I cannot see any plausible midfuture civilization having access to 2.4 million Tsar Bombas. If they do, then it will be a large and cumbersome weapon that is difficult to set off, not something that you can easily guarantee a kill with.

Now, to be fair, you can cause serious environmental damage with less than a dino killer. A Krakatoa - enough to cause a volcanic winter for one year leading to widespread death from famine, but soon blowing over with no lasting damage to the ecosystem and no major dent in existing political structures - would be 200 megatons of TNT, or only four Tsar Bombas - fairly affordable.

Overall, though, I expect that nuclear deployment strategies in interplanetary warfare will be about going for the jugular - you can't carry enough nukes to wipe out everyone, or even a significant fraction of everyone, but wiping out a couple of their most important cities could at least paralyze their civilization for a while.

End of life as we know it? Not gonna happen (nor is it something worth pursuing if all you really care about is the extinction of Homo sapiens). Even the Permian-Triassic extinction, even bigger than the more famous than the Cretaceous-Tertiary extinction, failed to wipe out metazoans or even amniotes.



SA Phil:

"Maybe even smaller than that. hundreds of rocks that impacted in the kiloton range would do wonders to softening up an enemy prior to an invasion. (in the brutal sense anyway)"

Kiloton range? Seriously? Bombs that size aren't even going to do more than starting some forest fires unless you can aim them well enough to ensure they'll land on a city. (The vast majority of the planet is uninhabited. Over half is ocean. You can't chuck rocks randomly and expect to do serious damage. See: Tunguska event.)

Hundreds of rocks in the kiloton range would amount to less than a megaton worth of dust, which would do negligible environmental damage. Gaia's response would be along the lines of "Hee, that tickles!".


"Although the idea of decelerating to attack a planet and sending massive amounts of radioactive materials its way seems a bit of a WMD prospect in and of itself."

You won't be pointing your exhaust directly at the planet. Your exhaust velocity will be above solar escape velocity, meaning that unless you point your exhaust very accurately, it'll soon be out of sight and out of mind forever.

Rick said...

Oops, yes, I meant I agreed with jollyreaper re 'planetbusting.'

NSWR is in effect a liquid-fuel Orion. Evaluating it is above my tech pay grade, but in general, I take Zubrin with a few grains of, well, salt. He's obviously a brilliant guy, but I'm not so sure he always cashes a reality check.

Anonymous said...

(SA Phil)

He does have a Phd in Nuclear Engineering though.

So I find it hard to dismiss the highly fissionable rocket idea out of hand.

jollyreaper said...

Regarding the plutonium economy -- reactor-grade fuel and bomb fuel are not the same thing so to get bomb fuel you have to set out to make it. As I understand it, gun type nukes are easy to knock together -- getting the fissile material is the hat part. Implosion bombs are a lot more complicated but building is still a lot easier than obtaining fissiles.

Big ol' engines and guidance computers are already there for your civilian economy. Rocks are going to be a part of the space economy.

So, would nukes still make more sense? Bearing in mind that they aren't really dual-use, to get bomb materiL you have to set out to get bomb material.

My gut tells me that it would be cheaper and less complicated to just use kk buses but I dot have the numbers to prove it. Would nukes not be as expensive as I'm thinking? Would they have too many advantages as opposed to just relying on rocks?

jollyreaper said...

End if life as we know it doesn't mean extinction of all life from cockroaches to lawyers. It's basically a phrase that means you will now view history as before and after that event.

For the record, I never bought the "wipe out all life" line for nuclear war. I think a big one had the potential of knocking us back to the stone age, end civilization for a thousand years. Maybe if we were lucky most of the weapons would fail due to shitty contracting and it would be a Warday novel scenario with civilization surviving in some form. A Threads or Day After scenario would be pretty much back to the stone age. I don't think it would go as far as On the Beach with human extinction. But even if it did, it wouldn't kill all life on Earth. Hyperbole. As Carlin said, the planet will be fine; humans, on the other hand, could be totally boned.

Anonymous said...

(SA Phil)
From the reading that I did following this latest Nuclear reactor --

Many of the objections to developing a Plutonium economy in our current technology is that it opens up the ability to process the Plutonium for use in Nuclear weapons.

So I suppose in my mind that it follows if you have the plutonium economy we are trying to avoid so badly because of the fear of Nuclear Proliferation ... weapons grade material becomes more available.

Anonymous said...

(SA Phil)

I recently watched that reboot Battlestar Galactica series.

The weird thing about that one was when they finally got to Earth and it was a nuked out ruin ... It caused me to scratch my head.

2000 year old nuclear war - - planet is uninhabitable.

How does that work? There are people living in Hiroshima today.

Anonymous said...

(SA Phil)

Basically it would be impossible to avoid developing a Plutonium Economy if you have a widespread interplanetary Space Travel. Since you need numerous Nuclear Reactors for power.

Using Uranium only would become problematic from a supply standpoint.

Teleros said...

Citizen Joe: "Lasers don't help against unguided kinetics. You might punch a few holes in the rock, but you're not altering its mass or course (significantly). What is worse is that you might be changing a big dodgeable object into hundreds of erratic undodgeable ones."

Certainly true... if you hit it dead on. A hit to one side may, especially if you can vaporise part of the missile, knock it off course.

As Rick notes though, unguided missiles have plenty of other problems though, mostly resulting from the combination of being unguided and slow (relative to, say, lasers, or even missiles that can accelerate using their on-board drive).



SA Phil: "Still it has to be hard to hit a bullet with a laser? Or perhaps not.

Possibly would depend on the size and range of the bullet.

And how long you have to line up the shot."


And beam diameter ;) .



Another thought, mainly for C. Joe: if you blow an incoming object into lots of little pieces with your PD laser, surely that will still be better from the defender's point of view? You've now got all that momentum & kinetic energy spread over a much larger surface area of your ship, reducing the damage at any one point.



jollyreaper: " The British Empire represented the high water mark of old school imperialism -- kick ass, occupy, extract wealth."

Horribly simplistic, actually - at least if we're talking about the British (there's something to be said for this if we were talking about Spanish treasure ships though). The British Empire was built for 3 main reasons:

-Commerce: China, India & the Caribbean, for example. The HEIC's army started out as a security force to protect trading posts; only after the right to tax Bengal was granted did the HEIC become a sort of privatised state.
-Living Space: North America & Australia. The colonists were often more violent WRT the natives than London.
-Global Strategy: South Africa, Egypt, Singapore, etc.



Milo: "Compared to missiles? Yes. Compared to unguided kinetics? No.

True, unguided kinetics can theoretically deal the same damage at any distance, while lasers fall off with the inverse square law. But kinetics' usable range will be limited by the distance at which you can reliably aim them and shoot them hard enough to not give the enemy time to dodge."


Yeah, I was thinking mainly of missiles, but even with unguided railgun slugs or similar, the key limitation is accuracy (at least for sieges), and that's much easier to work around than the inverse square law.

"Only if you're within laser range of the enemy. Unless your lasers have interplanetary ranges, it's going to be hard to get close without the enemy noticing you're acting shifty."

Well, you can build interplanetary lasers, and if you've got photon sails and such in your setting, you're likely to both have very big lasers, and the ability to build more.



SA Phil: "Thinking on that, Nuclear "point defense" missiles(10's of km+ really)..

Would be pretty effective for protection against clouds of incoming kinetics."


I dunno - like I said above, you probably could knock some off course by heating one side of a slug more than the other, but if there are lots of incoming kinetics, then I suspect you need to see about getting out of their way :P .

"2000 year old nuclear war - - planet is uninhabitable.

How does that work? There are people living in Hiroshima today."


Nukes are EVIL! EEEEEEEEEEEVIL!

But-

EEEEEEEVIL!

Thucydides said...

Really fast KKV's like the ORION asteroid buster design (100 G acceleration, capable of covering millions of kilometers in a few hours) are a path that will be seriously looked at. With impact energies of about a gigaton they can destroy any plausible midfuture(tm) space structures (up to Island Three colonies), hammer planetary installations (a near miss would still induce massive earthquakes on a small moon) and a direct hit would reduce Cheyenne Mountain to Cheyenne Lake (any other analogous installations would suffer the same fate).

Once again, this is more of a space ICBM than anything else (having a fortified base on the Moon or a NEO would probably address security issues and reduce objections to having such a thing nearby or launching from Earth). Once again we have to assume there is enough McGuffinite to justify a thriving space civilization and the requisite scale and scope of technology to make this future happen.

The "Space Navy" would be mostly security for the ORION and the pulse units and a technical staff down in the "hole" to monitor things and turn the keys when the order arrives, as well as a shuttle service to move personnel and equipment around. A subset of the Space Force would be installations to watch for enemy launches, and perhaps some form of ABM system to try and intercept incoming KKV's.

Anonymous said...

Luke, KraKon, thanks for the technical info; Those kind of detail really help! KraKon, you should look up ORION pulse modules; ORION and Casaba-Howitzer use the same pulse units, but the faceplace and 'nozzle' are a bit different; the ORION pulse unit uses a wide angle frontend and the faceplate is a thick piece of 'high Z' material (Z meaning atomic number) to give you a wide, slow pulse of plasma that transfers most of its momentum to the ship; the high speed, narrow pulse of the Casaba-Howitzer will punch through stuff like a sniper round through jello. So a few hundred Kilometers effective range is good; however, after that, how far is it a deadly pulse of cosmic rays? Probably 2-4 times that range on top of the hard kill range. Not quite the range I had hoped, but still good; And, of course, the use of which would induce that spinkter-clinching reaction in the side facing such a weapon...

Hmmm, perhaps I'll change the design to pulsed positron particle beams to ignite the LiH stream in my fusion rocket. Anyway, thaks again, guys!

Ferrell

jollyreaper said...


"2000 year old nuclear war - - planet is uninhabitable.

How does that work? There are people living in Hiroshima today."

Nukes are EVIL! EEEEEEEEEEEVIL!


Those were firecrackers compared to the stuff later developed, the thermonukes. From what I read they gave up on going much about 150kt per warhead -- too much energy wasted by radiating to space Rather than dropping megaton warheads on targets, the idea later developed to laying down a pattern of 150kt warheads over a large area, like nuclear carpet bombing. If I remember correctly the few megaton warheads were meant for surface bursts against extremely hard targets.

Our example in Hiroshima and Nagasaki are just two warheads -- 18 and 21 kt roughly a piece. The scale of destruction was not unprecedented -- the Tokyo firebombing killed 100k people destroyed more territory. The initial concern was simply that one plane could now cause the damage of a thousand -- the dangers of radiation were not yet fully appreciated.

So, Japan was able to rebuild from physical destruction on a scale comparable to a nuclear war but that was with massive assistance from the US. There was also no radioactive fallout to consider.

There's too many variables that we don't have the answer to. I generally like to stick with the idea of "Let's not have a war and find out what the breaks are." If the destruction is limited to the northern hemisphere, there might still be pockets of civilization that can muddle through. If we do have nuclear winter, there might not be any pockets of civilization that make it through. We're back to collapsing down to hunter-gatherer level. That's one hell of a slog back to proper civilization.

The number of bombs detonated on the surface of this planet already represent the results of a small nuclear war. I wonder how likely it is we'll see a regional nuclear war in the next 50 years. My biggest concern is something getting stupid in India or Pakistan.

Luke said...

Ferrell:

Hmmm, perhaps I'll change the design to pulsed positron particle beams to ignite the LiH stream in my fusion rocket.

Positrons probably are not the best choice ... too penetrating, as is their annihilation radiation. You want to compress the fusion fuel without heating it as much as possible before striking your spark to light off the fusion burn. If you hit the fuel pellet with penetrating radiation you heat it from the inside, which impedes compression. For particle beams, heavy ions tend to be the particles of choice.

Anonymous said...

(SA Phil)

Oh definitely Nukes are far more deadly than in World War 2


Its just that 2000 years is an extremely long time.

Anonymous said...

Luke,

It sounds like even Fusion Torches (if possible) - would still need fission reactors just to power their "light up"

Or beamed power, or something along those lines.

(SA Phil)

Luke said...

SA Phil:

It sounds like even Fusion Torches (if possible) - would still need fission reactors just to power their "light up"

You can directly tap the energy of the fusion pulse for power, using magnetohydrodynamics or flux compression or something similar. Energy tapped this way will not be available for propulsion, of course. Alternately, you can run a heat engine off of the waste heat created by the neutral radiation (but the efficiency will be lower, and the equipment more bulky). Since the driver beams will be a significant fraction of the energy per pulse, you will need efficient beams and generators to get net propulsive power - also inefficiencies in the beams will add a lot of waste heat directly to your spacecraft (a TW torch with 1% of the torch energy going into waste heat will need to deal with 10 GW of waste heat - that's a lot of radiators).

Anonymous said...

(SA Phil)

I was thinking more about the power needed to get the whole torch started.

Since the Torch is basically a short ranged energy inferno, you would need to move to a safe distance and "light up"

There would need to be some initial power, by the sounds of the beam requirements, etc, quite a lot of it.

Milo said...

Teleros:

"Yeah, I was thinking mainly of missiles, but even with unguided railgun slugs or similar, the key limitation is accuracy (at least for sieges), and that's much easier to work around than the inverse square law."

Even accelerating at only one milligee, you will displace 18 meters in one minute. (And unlike lasers, you can see the attack coming and so actively dodge rather than jink.) Thus, it is going to be effectively impossible to hit anything that the projectile takes more than one minute to reach.

If you're willing to accelerate at one decigee, you can displace that amount in 6 seconds. (Granted you can't do this too often without wasting your propellant - high accelerations are expensive.)

So just how fast can your kinetics move anyway?


"Well, you can build interplanetary lasers,"

Weren't you just claiming lasers have poor range?



Thucydides:

"100 G acceleration, capable of covering millions of kilometers in a few hours"

Once again, you're proposing delta-vees along the lines of 300 km/s with 100 gee accelerations. Not gonna happen.

And once again, it is impossible for any kinetic missile using ORION propulsion to make a bigger boom than is already contained in the nukes it uses for propulsion. Probably it will do considerably less due to inefficiencies.



SA Phil:

"It sounds like even Fusion Torches (if possible) - would still need fission reactors just to power their "light up""

How long do you need the ignition power for? If it's only a short burst of energy, then it's quite affordable to just carry it in batteries or ultracapacitors, which are considerably smaller than fission plants. Once your fusion reactor is running you can have it recharge the battery.

Teleros said...

Those who'd like a little more info on real-life nuclear warfare strategy (jollyreaper?), I'd suggest the following:

http://homepage.mac.com/msb/163x/faqs/nuclear_warfare_101.html

Also _102.html & _103.html for all 3 articles. Very interesting stuff.

jollyreaper said...

Teleros that's some really good material. Makes me wonder about what happens when you get someone in charge who doesn't understand the way things are done. Personally, I thought it was barking mad for them to try developing usable tactical nukes for bunker busting. Undone care if the yield is sub-kiloton, people would lose their minds the first time you said nuke. MRI had to be renamed from nuclear magnetic resonance.

The other fearful scenario would be the religious types. We like to think the leaders on each side are pragmatic, functionally agnostic and not believing in a hereafter. They want to keep their skins safe and will avoid war. But what happens when true believers take over Pakistan and feel that nuclear holocaust serves the agenda?

The same question could come up in space opera. Everyone knows you don't attack planets and now the revolutionary reliious council that took over the star nation has now started attacking planets with r-bombs. Interstellar genocide isn't a failure mode, it's part of the plan.

Raymond said...

Luke:

Out of curiosity, what's your take on antimatter-catalyzed microfission/microfusion?

Thucydides said...

Tactical nuclear weapons for bunker busting are a rational technical response to a difficult problem; i.e. how to deal with very deep bunkers and how to ensure toxic chemical and biological materials are destroyed with the bunker.

The fact that the political factors are so widely divergent from the technical factors is an additional complication, but then again, warfare is often a case of choosing from the "least worst" alternatives. If ensuring the Andromeda strain is destroyed is mission critical, then maybe it is worth dealing with the political implications of nuking a WMD bunker.

Byron said...

Sorry I missed the start of this. I was out of town.
My opinion on this is that we will see one weapon as dominant, simply because technology is unlikely to develop in such a way that weapons come out equal. Missiles dominate naval warfare today. Guns simply can't keep up with them in most roles. This is of course bad from a story perspective, but I really don't think that from an engineering perspective we can expect differently. The numbers just happened to work out in balance?

Some random thoughts:
Operatic drives reduce the effective range of lasers (see the last thread.)

There are actually two kinds of lasers for setting purposes: machine gun and cannon. These correspond loosely to CW and pulsed, but some pulsed applications (those at hertz levels) are machine gun type designs. I tend to favor cannons for story purposes, as they make things less mathematical.

Lasers and kinetics will likely have their places, but they are fundamentally different types of weapons. Laserstars are fundamentally tactical, while at PMF levels kinetics are fundamentally strategic. They can't accelerate to high speeds over tactical distances and scales. Missiles are not likely to be powerful enough to be terribly useful in either. This is about the only setting where I see them coexisting, and even then, they don't really operate in the same environment. A kinetic attack on laserstars will be a missile defense exercise. Kinetics
have no inherent staying power, which limits there utility. Projector kinetics will be much more like lasers, but I seriously doubt that both will be used. It's sort of like expecting missiles and guns to be equal enough that both are viable.

One problem we often have when discussing kinetics is that we ignore how they get launched. I posted on this earlier, and I won't repeat myself. However, there are limitations to all three methods.

I still think that getting rid of Earth is a good idea for story purposes. Here's the example I wrote for Rocketverse:
One day (September 17th, 2010) an event occurred. A substantial fraction of the human race was mysteriously transplanted to a different planet. Nobody knew how it happened. All that occurred was that one moment they were on Earth, and another they were on the new world. A total of 235 sites were moved from all over Earth, including whole cities. They were large enough that a semblance of modern technology was preserved. However, the limited resources of the new world, named a variety of things by a variety of different groups, forced intense competition. Some groups chose to leave, moving to the other habitable worlds of the system. Others stayed, and grew into powers. Others were absorbed, merged, or destroyed. Now, 350 old earth years after the event, the original world has become a squabbling backwater, while the various groups that left control the destiny of the system.
The world that they were transported to is of course 5-6. I hope this satisfies everyone.
And no, the history will not come into play. I wrote this to make Raymond stop whining.

Byron said...

More thoughts:
Why is anyone discussing unguided kinetics? I've dealt with this before, in space stations. They won't work efficiently, except at incredibly short ranges, the equivalent of smoothbore cannon range in the modern age. This can be overcome with huge amounts, but it's going to be cheaper to just guide them. The only exception is to guide a bunch to a reasonable range and dump them. That might work if really close point defense is too effective.

Orion could probably be made to work. I read the book on it, and it seems practical with enough money. That's in terms of engineering, of course. As to fuel, they figured out a way to get away with a lot less. Somewhere on the order of 1-2 kilograms, IIRC. The military optimizes for low total mass, not low fissile mass.
As to Zubrin, I'm going to classify that along with fusion torches. It strikes me as a case of not looking at the practical difficulties, like the engine melting. Why is it that all the cool ideas seem to have that? Zubrin, Bussard, O'Neil...

I'll have more later.

Anonymous said...

Ok, so if I use stripped Lithium ions at very high velocity, tightly focused, that should do the trick, right? Or should I use heavier a element?

Ferrell

Anonymous said...

Ok, reread Luke's post and realized I had missed the heavy in heavy ion...so I should use something like stripped uranium ions...unless that's overkill?

Ferrell

Anonymous said...

(SA Phil)

I believe I had been one of the ones discussing unguided kinetics. But I do not see them working unless the (relative) speed/ distance is such that they would be effective.

So -- close range .. at 100km a Railgun would be pretty effective.

Or somehow getting the speed up to 100 / 200 kms /something that again makes the closing time much shorter.

----------------
After what Luke explained about the heat on fusion torches I was wondering that also about the Zubrin rocket. Since to get high thrust and high ISP it means massive power -- unless the system is extremely efficient, some part of the drive would melt.

Which tends to suggest that all Torches are inherently problematic. No matter what the technology is that creates them the real problem is not melting the back of your space craft.

Tony said...

Byron:

"Lasers and kinetics will likely have their places, but they are fundamentally different types of weapons. Laserstars are fundamentally tactical, while at PMF levels kinetics are fundamentally strategic. They can't accelerate to high speeds over tactical distances and scales. Missiles are not likely to be powerful enough to be terribly useful in either. This is about the only setting where I see them coexisting, and even then, they don't really operate in the same environment. A kinetic attack on laserstars will be a missile defense exercise. Kinetics
have no inherent staying power, which limits there utility. Projector kinetics will be much more like lasers, but I seriously doubt that both will be used. It's sort of like expecting missiles and guns to be equal enough that both are viable."


The above is valid only for highly nuanced values of "tactical" and "strategic". (And where did the operational level of warfare disappear to?) It only takes accelerating at 5 Gs for 100 seconds to get a 5 km/sec change in velocity, which should be adequate for a kinetic attack with anything larger than a soda can. In that time, the missile launching the kinetic bus travels a whole whopping 250 km. Unless we're counting only visual range as tactical, I think that could be regarded as tactical. Also, an average of 5 Gs for 100 seconds is pretty much within the envelope of ICBM and SLBM first stages. You could probably launch a bus with 50-100 10 kg brillaint pebbles with one of those. Makes for kind of a big antiship missile, but as we are constantly being reminded, the scale of space is different.

WRT staying power, if two of my ships each launch four kinetic bus missiles at two of your laserstars, and both laserstars are killed, while only one of my ships is, my remaining unit, and it's remaining weapons, has all the staying power it needs. See, you're behaving as if a kinetic buss is a spaceship. It's not. It's a round of ammunition, launched on a ballistic attack by a missile launched from a ship or by the hsip itself. It's the ship that has the staying power, ans always has had.

Byron said...

Tony:
Yes. And what good is 5 km/s against a laserstar with a range in the tenths of light-seconds, particularly when the missile makes its presence known? And across those sorts of ranges, 5 km/s is pretty slow. I don't think it will work without demi-torch missiles. And the staying power comment was meant WRT big busses (ship/missile hybrids). You only get one pass.
I do get that for some scenarios, the buss is ammo, but for others it is a ship.

Luke said...

Raymond:

Out of curiosity, what's your take on antimatter-catalyzed microfission/microfusion?

From what I have read, you can use the nuclear fragments resulting from antimatter annihilation of heavy nuclei to reduce the necessary compression needed for fusion ignition. How much better this is than fast ignition, I am not sure. It does vary with the amount of antimatter you are willing to use.

The less compression you need, the smaller the lasers you can get away with and the less waste heat you have delivered to your spacecraft from the operation of the lasers (or ion beams, or whatever).

Luke said...

Ferrell:

so I should use something like stripped uranium ions...unless that's overkill?

Most research on fusion driver beams has been on lasers. I know that heavy ion beams were under consideration, but I don't know how heavy. Uranium is probably unnecessary - lead would work if you need something extremely heavy.

Tony said...

Byron:

"Yes. And what good is 5 km/s against a laserstar with a range in the tenths of light-seconds, particularly when the missile makes its presence known? And across those sorts of ranges, 5 km/s is pretty slow. I don't think it will work without demi-torch missiles. And the staying power comment was meant WRT big busses (ship/missile hybrids). You only get one pass."

You were making your point explicitly in the plausible midfuture ("PMF") context. In that context, you aren't going to have fractional light second laser effective ranges. The power plants, using current or reasonably foreseeable launch and power generation technology, are going to be too expensive to lift off of the Earth.

And don't complain about wanting to talk about technology without talking about economics. They don't exist in mutual isolation. They never have. If you want to hang your hat on the "plausible", banish from your brain housing group anything that isn't practical, no matter how theoretically valid or Romantically cool.

"I do get that for some scenarios, the buss is ammo, but for others it is a ship."

A bus is by definition an article of ammunition. It carries some number of submunitions and releases them at the proper time in the mission profile. Now, a bus's delivery system may be a ship or a missile. But those are separate entities, both in engineering terms and in mission planning.

Luke said...

SA Phil:

After what Luke explained about the heat on fusion torches I was wondering that also about the Zubrin rocket. Since to get high thrust and high ISP it means massive power -- unless the system is extremely efficient, some part of the drive would melt.

I am away from my references at the moment, but if I am recalling correctly about 5% of the fission energy is released as neutrons and somewhere around 5% as prompt gamma rays. Neglecting any x-rays, this gives about 10% of your energy as neutral radiation that you need to worry about, which could heat the spacecraft.

Thucydides said...

While there is no doubt that laser weapons are technically challenging, work is continuing apace. Laser weapons have been demonstrated from several different types of aircraft, ranging from converted 747's to C-130's, and the US Navy recently set a small boat on fire from a range of 1.6Km in open water (both ships moving).

Space does not have an atmosphere, turbulence, engine vibration from 4 turboprops or wave motion to upset the optical train, so it is easier for these weapons to operate in space.

A megawatt class weapon is described for use in a 747 sized carrier, which implies that a spacecraft or platform as large as a 747 can also be designed to carry such a weapon (and the pieces can be assembled in orbit, the ISS weighs 800 tons, considerably more than a 747). http://www1.jlab.org/Ul/Publications/documents/JLAB-CIO-05-02.pdf

The 747 could even stand in for the rough outline of the spacecraft, think of the wings as radiators and put a sensor dome in the "hump" along with the crew. The analogy breaks down as we go towards the rear end of the spacecraft, now we need the nuclear reactor, Vasmir engines etc...

Byron said...

Tony:
If we assume that there are 30,000 km range lasers, then 5 km/s is useless. Period. Stop throwing out red herrings. I don't agree with you on lifting or on laser effectiveness. However, the above statement stands.
If you want to hang your hat on the "plausible", banish from your brain housing group anything that isn't practical, no matter how theoretically valid or Romantically cool.
In that case, there is no manned space program. What's this I hear about a space shuttle? Someone's being impractical. And what do you mean, solid-state weapons-grade lasers?

A bus is by definition an article of ammunition. It carries some number of submunitions and releases them at the proper time in the mission profile. Now, a bus's delivery system may be a ship or a missile. But those are separate entities, both in engineering terms and in mission planning.
Excuse me for imprecise terminology. That sentence should read "I do get that for some scenarios, the buss is attached to a missile, but for others it is attached to a ship."
That doesn't change the point. For high-speed kinetics, you only get one pass.

The above is valid only for highly nuanced values of "tactical" and "strategic". (And where did the operational level of warfare disappear to?)
Fine. I forgot to tie my terms down well enough. Surely you will agree that they operate on different scales and with different response times, whatever we may choose to call those levels.

Scott said...

As I understand it, gun type nukes are easy to knock together -- getting the fissile material is the hat part. Implosion bombs are a lot more complicated but building is still a lot easier than obtaining fissiles.

Not quite correct. The implosion lens is the single most complex piece of engineering possibly ever accomplished. A very reliable gun-type bomb can be built with 1930s technology and Uranium. Thing is, you cannot use Plutonium in gun designs. Talk to a nuke engineer why, all I know is that it doesn't work. Plutonium must be imploded to fiss.

=====
Are you sure that the Krakatoa blast was only 200MT? St Helens was ~24Mt, and Krakatoa was ... only 10x the size. Nevermind.

But let's wander down the nuclear rabbithole for a minute. A single Ohio-class sub carries up to 24 Trident II/D5 missiles. Each missile was designed to carry up to a dozen 475kt warheads (according to wikipedia and Janes). That's 136,800kt. There are 14 Ohio-class subs in strategic service, but not all of them are deployed at one time. Let's assume that 3 out of 4 are available, which is ~10. So a rough guess at the submarine result for a seriously pissed off US is 1.4gigatons, and triple that for the rest of the US arsenal. 4.1 gigatons of boom.

The Russians had bigger warheads and more of them, so now we're up to a total yield greater than 10 gigatons. That's roughly the size of the Yellowstone Caldera explosion, but spread all over the world and concentrated on major food-producing regions.

Still think that global thermonuclear war isn't an extinction-level event?

You'd need to get a kinetic moving really fast to deal that kind of damage, like .9c or so!

KraKon said...

From the E.N.D...

"The Russians had bigger warheads and more of them, so now we're up to a total yield greater than 10 gigatons. That's roughly the size of the Yellowstone Caldera explosion, but spread all over the world and concentrated on major food-producing regions.

Still think that global thermonuclear war isn't an extinction-level event?"

People can survive in radiation environments that we need protection suits for today-0.5 Gray with no noticeable effects. 5 microsieverts natural background radiation, AFTER nuclear testing, is really small in comparison.
Nuclear fallout creates radiation that are reduced on a logarithmic scale after mere days.
So no, no EXTINCTION level event. The human race can survive even if the age expectancy was reduced to 30. What WILL happen is civilization collapse, or at least in the parts bombed. As Modern Man is vaporized in the office buildings, a hardy Kenyan Tribe moves up from the desert and conquers the Miditerranean.

"You'd need to get a kinetic moving really fast to deal that kind of damage, like .9c or so!"

10kg at 0.9c releases 87 gigatons upon impact. That's a lot.


"If we assume that there are 30,000 km range lasers, then 5 km/s is useless. Period. Stop throwing out red herrings."

The effectiveness of dumb kinetics is in function of the projectile's velocity, the target's dodge acceleration and the laser effectiveness range;
you divide the laser's range by the kinetic's velocity-you then use this time to find out if the target has moved outside of initial position (ie moved 10m while preseting 5m to the enemy).

In the 300000km range example, a 15m wide craft with milligee acceleration is only vulnerable to
projectiles travelling at 556km/s

If the range is cut to 1000km, a more manageable 18.5km/s is enough.

"Neglecting any x-rays, this gives about 10% of your energy as neutral radiation that you need to worry about, which could heat the spacecraft."

I thought the meters of water between the reaction and the back of the reaction chamber doubled as fluid radiation shielding. The reactor walls are thin so they can radiate a lot of the imparted heat, and the flowing water acts as expendible coolant...if needed a layer of cold water can be run against the walls (or oil) while hot water stays in the center.

"The less compression you need, the smaller the lasers you can get away with and the less waste heat you have delivered to your spacecraft from the operation of the lasers (or ion beams, or whatever)."

The less the ignition is based on onboard energy, the weaker the lasers and the better the combat. Waste heat is not a big problem because the energy is expended during a millisecond. Power levels are high, total energy low.
I also prefer ion ignition to laser ignition (if not compression too) as linear accelerators are more efficient than lasers at any power level. They just mass more...I'm willing to sacrifice mass for electric-engine type efficiencies (98%+ against 10-60% for lasers)

"Which tends to suggest that all Torches are inherently problematic. No matter what the technology is that creates them the real problem is not melting the back of your space craft."

Which leads to the sensible removal of the reaction chamber and the design of an external pulse drive. Terrawatts without the hassle.

KraKon said...

"So -- close range .. at 100km a Railgun would be pretty effective.

Or somehow getting the speed up to 100 / 200 kms /something that again makes the closing time much shorter. "

The solutions are reducing effective range of lasers, decreasing maneouverability (we don't want that) and increasing projectile velocity (hard) or ability to follow target (dead easy).
If you choose the latter solution, just make sure the missile isn't bought down on route.
100km/s is extremely hard-I tell you.
And since projectorstars have to release all that energy in the millisecond release time, they have incredible power levels they're just better off feeding the laser with.
Coilguns weigh a lot too.
My solution was a) reduce effectiveness of lasers. I didn't hit plausibility by reducing laser power levels. Then what did you do, Krakon?!
I spun it up. I spread the beam spot over a surface 471 times larger during the pulse...with corresponding two orders of magnitude reduction of penetration...
The lasers now accelerate the kinetics. Since the lasers are on the GW level, and the missiles are on the kg-range....they get 100's of g's of trust and end velocities of 80km/s!
Acceleratorstars...accelstars?

"Lasers and kinetics will likely have their places, but they are fundamentally different types of weapons."

The lines can be mixed if we have fast kinetics/weak lasers, or interplanetary lasers/slow kinetics. Or if lasers and kinetics are a since weapon system...

"How long do you need the ignition power for? If it's only a short burst of energy, then it's quite affordable to just carry it in batteries or ultracapacitors, which are considerably smaller than fission plants. Once your fusion reactor is running you can have it recharge the battery."

Around a millisecond. The implosion is around 2-4 milliseconds. Total energy released is around a megajoule, but power levels in the gigawatts.
It might be that you just don't have ultracapacitors with that high a discharge rate...

"Since the driver beams will be a significant fraction of the energy per pulse, you will need efficient beams and generators to get net propulsive power - also inefficiencies in the beams will add a lot of waste heat directly to your spacecraft (a TW torch with 1% of the torch energy going into waste heat will need to deal with 10 GW of waste heat - that's a lot of radiators)."

True...but only for small pulses, ignited through a high energy system. For a large pulse, the initial energy is the same but the resultant blast is proportionaly more powerful. 10GW might ignite a kiloton pellet, or a kiloton pellet with a gigaton second stage (just for example...gigaton is useless). Or you can use antimatter/non-energy based ignition. Like I do. The laser compression only takes up an infitisimal fraction of the drive energy, and antiprotons do the rest.

Teleros said...

Scott: Still think that global thermonuclear war isn't an extinction-level event?

You'd need to get a kinetic moving really fast to deal that kind of damage, like .9c or so!


Read those articles I linked above about nuclear warfare. Aside from targeting priorities, we've never had enough boom to wipe ourselves out, let alone all life on Earth.

As for kinetics, you're forgetting the mass involved - a nice big asteroid will do the job, and it doesn't have to be moving particularly fast either. Also the numbers - we need a LOT of nukes to get up to that 10GT mark, so comparing thousands of warheads to a single missile... :P

Raymond said...

Luke:

The Penn State University papers I've read through (see here: http://www.engr.psu.edu/antimatter/documents.html) don't include a driver beam for the AIMStar, their version of antimatter-catalyzed microfusion relying on antiprotons in a double-nested potential well, and fuel pellets composed of D-T or D-He3 surrounded by a thin shell of U235. Now, the microfission version they proposed with ICAN-II does mention an ion driver, but doesn't provide much in the way of details.

As far as the torch-drive-heating-the-ship problem, the Penn State team made this a feature; the propellant for the ICAN-II craft was a silicon-carbide ablative thrust shell.

Tony:

"You were making your point explicitly in the plausible midfuture ("PMF") context. In that context, you aren't going to have fractional light second laser effective ranges. The power plants, using current or reasonably foreseeable launch and power generation technology, are going to be too expensive to lift off of the Earth."

Please, stop blithely asserting this. You keep ignoring the (repeatedly demonstrated) fact that the powerplants necessary for interplanetary travel will by definition have enough onboard power for a large laser. Even with demi-torches, as explained, you'll require laser or ion drivers of the same power class. If we don't have big enough reactors to power a 100 MW laser, we also don't have even milligee nuke-electric drives.

"I don't believe that they [lasers] could be kept stable enough to attack small homing kinetics at more than a few thousand kilometers at best."

A few thousand km is fine, thanks. Give me three thousand klicks and kinetics closing at 5 km/s, and I've got 600 seconds to pick off your hundred pebbles. Average of 6 s per. That's a lot of time to snipe away.

Oh, and the same laser I'm using for that can probably scorch your laser mirror or do one of those radiator-overload attacks at thirty thousand.

KraKon:

"It might be that you just don't have ultracapacitors with that high a discharge rate..."

We do.

"10GW might ignite a kiloton pellet, or a kiloton pellet with a gigaton second stage (just for example...gigaton is useless). Or you can use antimatter/non-energy based ignition. Like I do. The laser compression only takes up an infitisimal fraction of the drive energy, and antiprotons do the rest."

Other way around. The 10 GW waste heat for a TW torch was an optimistic case of propulsive inefficiency.

"The effectiveness of dumb kinetics is in function of the projectile's velocity, the target's dodge acceleration and the laser effectiveness range;
you divide the laser's range by the kinetic's velocity-you then use this time to find out if the target has moved outside of initial position (ie moved 10m while preseting 5m to the enemy)."


I think everybody's been assuming at least terminal guidance on kinetics, regardless of the initial launch mechanism. Too hard to hit anything except at point blank with unguided rounds.

Scott:

I wouldn't necessarily bet on much of a plutonium economy resulting from space reactors. Most of the proposed designs (molten salt, liquid core, gas core, solid-core gas-cooled) have much higher burnup than terrestrial PWRs, and some of said designs are amenable to the Thorium cycle anyways (which would help with fuel supply and reduce launch concerns).

KraKon said...

"As for kinetics, you're forgetting the mass involved - a nice big asteroid will do the job, and it doesn't have to be moving particularly fast either."

The main problems here is that moving any asteroid to the target would need a massive investment in remass and drive power. Essentially, the whole mass of the asteroid becomes your payload, and you can't use it as remass itself (unless it is some kind of comet, and you're on a thermal rocket...worse than milligee at PMF). There are also issues with actually finding the right asteroid, one with significant mass, doesn't need much dV to change it's orbit (incompatible with above) and actually passes near the target (pretty much the same as above).

"Also the numbers - we need a LOT of nukes to get up to that 10GT mark, so comparing thousands of warheads to a single missile... :P"

You've just detonated several hundreds of nuclear charges to accelerate the missile, so the kinetic energy is by definition LESS THAN THE SUM of the energy contained in the fuel expended. Actually, with the old boom-boom, around 10-20%, since not only is it a thermal system, it is based on a physical pusher plate, and each charge loses energy density to casing and igniters, THEN you lose efficiency with each charge being a small nuke...

In other words, I remove all the charges used to accelerate the missile, remove the nuclear fuel, put is all in one big bomb with a SINGLE case and a SINGLE igniter (the orginal would do). It would be a small charge, and the rest of the nuclear fuel as a second stage who's power just goes up with how much more fissiles you put in it.

Put this several TEN's of gigatons nuclear charge on a slow nuc-electris bus, and let it coast to target.
Asteroids may be big, and/or fast, but they don't jink, so you can easily catch up with it.

Byron said...

Scott:
I'm pretty sure that they don't carry 10. Wikipedia says that Trident IIs carry 8 and will be reducing that to 4 or 5.

KraKon:
I never mentioned a word about unguided. I was pointing out that it was closing too slowly to be able to get through the lasers's defenses. I do understand how to do the math on that, as I've done it before.
If we do use lasers to boost kinetics, that falls under a plausible demi-torch drive (as you get rid of the power plant).
I don't think that single big warheads are a good idea, though. Read the links posted about Nuclear Warfare. You're going to want medium-size weapons.

Thucydides said...

Once again it boils down to what exactly the stakes are.

Early black powder warfare was expensive, and the stakes were usually limited to trading small pieces of territory back and forth or putting a suitable puppet on the throne. Warfare was essentially limited to small semi professional armies.

The French Revolution made a vast change to the political landscape and threatened not just some territory but the entire social and political structure of Europe. The French threw off the restraints first (to counter the massing of professional armies) but soon everyone was "all in".

We see similar changes in scale as the stakes change, Canada had a "Permanent Militia" of about 3000 members prior to the outbreak of WWII, the existential nature of the threat led to a million men under arms and the world's third largest Navy by the end of the Second World War.

If the plausible midfuture(tm) setting has small colonies busy with their McGuffinite, they will probably only invest in small security forces to keep people from wandering out of airlocks or screwing up the accounting computers.

Earth, on the other hand, will be very concerned about accidental or malicious diversion of objects into orbit crossing paths, and build a force to deal with that scenario. They can do ICBM's in Space, build a space navy capable of frying or diverting incoming objects or (probably the cheapest option) send occupying forces to ensure the colonies don't start playing with rocks or unconstrained energies.

Later, as colonies develop their own unique cultures, we may see religions or ideologies that demand converts, raising warfare to existential threat levels. That will be what drives the development of larger, more capable space war doctrines and technologies.

As an aside, I wonder if the combination of aversion to all things nuclear and the limits of lifting power Tony alludes to will sideline nuclear fission reactors as a practical power source in space. Solar energy of some form will do out to Mars, and Jovian ships and infrastructure can capture energy from the planet's magnetosphere, so we could be looking at a very much different paradigm for ships in the plausible midfuture(tm).

Tony said...

Byron:

"If we assume that there are 30,000 km range lasers, then 5 km/s is useless. Period. Stop throwing out red herrings."

You have a very bad habit of assuming maximum technical range is the same thing as maximum effective range. A 10 kg brilliant pebble roughly the size of a basketball is not likely detectable at 30k km, much less engageable.

"I don't agree with you on lifting or on laser effectiveness. However, the above statement stands."

No it doesn't. It's precisely our disagreement about the limits of technology that is causing the discussion to continue. If you think you're right, that's fine, but you can't demonstrate to me that you are. Essentially, you are making assertions based on nothing but positivist thinking, while I am questioning the basis of your positivity.

"In that case, there is no manned space program. What's this I hear about a space shuttle? Someone's being impractical."

Since I totally agree that the Space Shuttle was impractical and wrong, what's your point?

"And what do you mean, solid-state weapons-grade lasers?"

I have no problem with lasers existing. I'm wquestioning whether their technical practicality translates into military utility. And I really don't question that. What I'm questioning is whether lasers' technical capabilities in a perfect physics thought experiment has anything to do with real world performance.

"Excuse me for imprecise terminology. That sentence should read 'I do get that for some scenarios, the buss is attached to a missile, but for others it is attached to a ship.'"

Agreeing on terminology is the first step towards communication. You can't have an interface without an interface convention.

"That doesn't change the point. For high-speed kinetics, you only get one pass."

If the ship launches a missile, the ship is still there. Even if a ship launches a ballistic attack directly, there's nothing keeping the ship from decelerating behind the attack to enter orbit at the objective. That's why the bus is a munitions item and the ship isn't, and why it's important to make the distinction.

"Fine. I forgot to tie my terms down well enough. Surely you will agree that they operate on different scales and with different response times, whatever we may choose to call those levels."

But I don't agree. The assumption you seem to be working on is that the laser will be instantly ready to go; that it will have no limitations on accuracy, shot-to-shot precision, or number of engagements; and will kill anything it shoots at on every shot. Now, while our friends with military aand technology management experience settle down, please let me politely inform you that you that none of those things is likely. The guys with the kinetics are just as likely to get off the first shot as the guys with the lasers, the lasers are just as likely not to get hits on incoming kinetics as they are likely to, and it won't matter one bit how many shots a laser has in its quiver if the guys with the kinetics have done their homework and come with enough shots to take care of the lasers. A machine gun with an infinite ammo supply is just as dead if a mortar neutralizes it as if another infinite repeater does.

jollyreaper said...


The Russians had bigger warheads and more of them, so now we're up to a total yield greater than 10 gigatons. That's roughly the size of the Yellowstone Caldera explosion, but spread all over the world and concentrated on major food-producing regions.

Still think that global thermonuclear war isn't an extinction-level event?


That link to the 163x site was pretty interesting. The guy talking there had a lot of experience with nukes. He mentioned how the public impression of them isn't quite what the reality is like. We tend to imagine targets hit by nukes will be scraped clean down to bedrock but there will be a surprising number of seemingly intact structures outside the blast zone.

He maintains the big danger is the collapse of technological society after the attack. The figures they were looking at were 60% effectiveness with the ICBM bus, let alone questions of warhead reliability. So depending on how much you fudge the numbers on operational effectiveness, the gamut runs from small war to big war to apocalypse. And he's quite adamant that extinction of the pre-war society as we would know it is pretty much a given. He's optimistic about only dropping back to American colonial-era technology with death coming from the most banal diseases and accidents modern medicine handles with ease. That's a lot more optimistic than my thought of getting blasted back to hunter-gatherer levels. The source is outright skeptical of severe nuclear winter claims and feels we'd probably have a nuclear autumn instead.

Needless to say, even with the specific numbers bandied about by people who deal with this for a living, there's not any winners in nuclear war, just a question of how badly you lose. He's very optimistic about the sobering effect nukes have on political leadership. There's no going into retirement in France when you lose a nuclear war. There's no comfy exile in luxury. You get into a nuclear war, you're going to be as screwed as everyone else. I'm only scared of people who can convince themselves otherwise.

Tony said...

Raymond:

"Please, stop blithely asserting this. You keep ignoring the (repeatedly demonstrated) fact that the powerplants necessary for interplanetary travel will by definition have enough onboard power for a large laser. Even with demi-torches, as explained, you'll require laser or ion drivers of the same power class. If we don't have big enough reactors to power a 100 MW laser, we also don't have even milligee nuke-electric drives."

The conversation at one point strayed to the discussion of thousand ton gigawatt reactors, powering gigawatt lasers. That's what I was referring to. 100 MW lasers would be within the realm of believability, but the same problems of accuracy and precision that have already been discussed still apply.

"A few thousand km is fine, thanks. Give me three thousand klicks and kinetics closing at 5 km/s, and I've got 600 seconds to pick off your hundred pebbles. Average of 6 s per. That's a lot of time to snipe away."

Six seconds per incoming attacker is an uncomfortably short time, even with full computerized automation. In that time you have to acquire the target, align the weapon, take a shot, do battle damage assesment (BDA), reengage if necessary, and repeat as many times as necessary to ensure a kill. The BDA is really going to be the hard part. What are you looking for? Outgassing? The attackers' maneuvering thrusters give you that. Change in trajectory? The enemy does that without your help too. Debris? How long does it take for a debris cloud to be distinguishable from an intact target? Even if you run through the target array once without worrying about BDA, you still have to run through the whole thing again doing BDA assesment. Even with a devoted BDA sensor, how long before you're sure? Six seconds per projectile? If I was the attacker, I'd take that and laugh all the way to the bank.

"Oh, and the same laser I'm using for that can probably scorch your laser mirror or do one of those radiator-overload attacks at thirty thousand."

I'm not using long range lasers or putting my radiators close enough to you to take those shots at it. I already made up my mind that it's stupid to do so.

Raymond said...

Tony:

"The conversation at one point strayed to the discussion of thousand ton gigawatt reactors, powering gigawatt lasers. That's what I was referring to. 100 MW lasers would be within the realm of believability, but the same problems of accuracy and precision that have already been discussed still apply."

Any kiloton nuclear-electric spacecraft with specific power in the ~1 kW/kg range will have a gigawatt on tap. And if we're out in space in sufficient numbers to make large-scale warfare possible, we've probably got spacecraft that large.

Mind you, for the record, my expectations are a little closer to yours than you may think. Most of the big, overwhelming laser concepts aren't in the visual range, but more likely in the hard UV or soft X-ray wavelengths, which go a lot further with 100 MW than visible.

A laser in the 100 MW range (inside the power generation envelope of a sub-kiloton nuke-electric craft) with a 10-meter mirror (less than twice the diameter of the James Webb) can burn through non-trivial amounts of carbon armor beginning at 3000-6000 km (depending on how close to the diffraction limit your laser can get). This is useful, and depending on the mass required may serve as an important part of a warcraft's armament, but by no means is it an overwhelming primary weapon.

"Six seconds per incoming attacker is an uncomfortably short time, even with full computerized automation...."

Depends on time required to change targets, angular distance between targets, etc. If the incoming projectiles are close enough together (which they probably would be, if launched from the same missile group), I think the better strategy would be to fire on each target in sequence without BDA, then make a short burn and light them up with active lidar (or use passive infrared, if it's sensitive enough) - any incoming projectiles which change course to follow are considered still active, and must be re-engaged.

Byron said...

Tony:
You have a very bad habit of assuming maximum technical range is the same thing as maximum effective range. A 10 kg brilliant pebble roughly the size of a basketball is not likely detectable at 30k km, much less engageable.
Um, no. That's a red herring. I said that if said lasers exist, then 5 km/s kinetics are useless. Do you disagree with that, or not?
And why can't they be detected? I'll have a fairly good idea of where they are, as you're proposing using missiles to launch them. That tells me where to look. If there are no targets in range, I sweep with my laser in lidar mode, and when I pick them up, I shoot.
For that matter, SBX has a range against a baseball-sized target of close to 3,000 km. I know it's heavy, but it's current technology, your projectiles will be bigger, and it's not designed for space. I don't see this as insurmountable.

Since I totally agree that the Space Shuttle was impractical and wrong, what's your point?
By your logic, any story that incorporates it isn't plausible. That's my point.

If the ship launches a missile, the ship is still there. Even if a ship launches a ballistic attack directly, there's nothing keeping the ship from decelerating behind the attack to enter orbit at the objective. That's why the bus is a munitions item and the ship isn't, and why it's important to make the distinction.
By high-speed I mean in the 30 km/s range. I don't see chemical missiles getting above 5 km/s or so, which is too slow in a universe of .1 ls lasers. (I know you don't think they will exist. However, if they do, chemfuel missiles are out.) That sort of velocity is only achievable with a miligee drive, which can't reach those speeds on a tactical timescale. If you're outlawing the lasers, the picture changes.

The guys with the kinetics are just as likely to get off the first shot as the guys with the lasers, the lasers are just as likely not to get hits on incoming kinetics as they are likely to, and it won't matter one bit how many shots a laser has in its quiver if the guys with the kinetics have done their homework and come with enough shots to take care of the lasers.
But they have to have those shots. Your argument is the same as saying that carriers are obsolete because enough ASMs can take one out. But ASMs are far better at sea denial than sea control, and the same applies here. Missiles can work, but I question them being powerful enough compared to lasers. I could be wrong, but I also could be right.

Milo said...

Scott:

Now you're talking about the combined force of all nukes on the planet. How exactly are we going to convey all nukes on the planet to an enemy on Mars?

That's a fleet-level action. While a midfuture space armada could probably deliver those nukes, it would be a major operation with a significant commitment of resources, not the "one plane can ruin your whole day" thing that current nukes have going.

Meanwhile while you spent your planet's entire defense budget on interplanetary bombers to carry all your nukes, I spent my planet's entire defense budget on interplanetary battleships to kill your bombers in transit. So much for that.



Teleros:

"As for kinetics, you're forgetting the mass involved - a nice big asteroid will do the job, and it doesn't have to be moving particularly fast either."

No, but you do need to move your nice big asteroid by interplanetary distances over a short time span.

Really big asteroids are, in the midfuture, going to be considered immobile terrain. You might as well talk about throwing a mountain at someone.

Anonymous said...

Ok, everyone, I've got a scenario for you to argue about:)

The Grand Republic of Northern Barsoom has decided that the EU has meddled in their affairs one too many times, so they launch a battle consillation to shotgun Europe with kinetic warheads; the EU finds out and sends an interception constillation. Both are equiped with lasers, short-range particle beam weapons, and various types of kinetics. Both groups reach 30 Kps for a closing velocity of 60 Kps; each side has main lasers that have a maxium effective range of 6000Km and can hit ten targets per second (I know I'm being very generous)with the PD particle beams able to hit 30 targets total. Assume four PD turrets per ship. Each ship carries several kinetic busses that carry 280 soda-can-sized miniture homing vehicles (H-SCOD) each; several missiles used to kill busses (assume two missiles per buss to insure a hard kill). So each ship can be killed by four busses (H-SCOD's + buss), and each buss-killer missile takes up half the volume and mass of a buss. The intercept would be like this: )(, and would last about 200 seconds (100 closing, 100 retreating) but kinetics would only be useful during the closing phase. Assume both side have the same number of ships and have roughly the same payload capacity, give or take 5%; How would one side or the other win?

Ferrell

ElAntonius said...

Ferrell: I won't work any math out because as a thought experiment I think it's safe to say that on typical interception missions the defender holds an overwhelming advantage.

Assuming both sides are sending manned craft, then the defenders hold a fuel advantage in that they can define the length of their intercept.

The defender also does not have to reserve payload for the offensive mission (the attacker has to have some payload dedicated to the attack).

Between those two facts, it's entirely possible that the defenders can mission kill the attacking fleet even if they are destroyed to the last ship, simply by forcing weapon expenditure and remass expenditure.

However, this brings an additional question...if the objective is to saturate targets in the EU, why are they sending a constellation at all? KKV saturation will do, I think...they're better off trying to saturate point defense by sending more KKVs per ton than they are trying to send equivalent ships and trying to win orbital control.

Tony said...

Re: Raymond

Okay...

A circle can be divided into 6400 mils. Why? A mil happens to be very close to 1/1000 of a radian (0.000981746875 radians to be as precise as my Windoze calculator cares to be). So a bunch of French artillery officers got together and decided to divide the circle into 6400 (sort of) milliradians, or "mils", in order to make the math easier. Hey, it was close enough for government work.

This not quite arbitrary decision led to an interesting phenomenon in measurement of angular distances. Using an arbitrary unit of measure, a mil of apparent width approximately equals 1 unit of physical width at a distance of 1000 units. Or you can think about it another way: one unit of actual width equals one mil of apparent width at 1000 units distance. For example, an object two units wide at 1000 units distance will appear to be two mils wide. We'll need to know this later.

Why is this important? Well, it turns out that military grade pointing precision for guns is generally specified as 1.0 mils. 0.5 mils is considered high precision. At that level of precision, a laser fired at a target 5000 km distant could hit anywhere within a 2.5 km circle. Not so good, huh?

A circle can also be divided into arcseconds, 1296000 of them to be exact. That means that an arcsecond is pretty close to 1/200 of a mil. So let's say we could achieve arcsecond precision with our laser cannon, or 100 times the 0.5 mils precision quoted above. That still gives a circle of error 25 meters in diameter at 5000 km. And you're trying to hit a target 0.5 m in diameter (at most).

All very interesting, I hear you say, but let's relate this to the real world. Okay, the arcsecond level of pointing precision eqates to a ratio of 1 unit of error per 200,000 units of distance. (That's 1 mil / 1000 units * 200 arcseconds-per-mil.) And we can relate that to data about the current level of achievable pointing precision. The Airborne Laser is supposed to be able to punch a hole in a liquid fueld rocket tank at 600 km. Say that the technical requirement is to hold a laser spot inside a 0.5 m circle at the specified range. That's a ratio of 1/1200000. (Or one sixth of an arcsecond, if you want to look at it that way.) Going back to our laserstar engaging a brilliant pebble at 5000 km, it turns out the error circle is still about 4 m in diameter. Using simplistic assumptions, that means you get one hit in 16 shots at that range. The range of sure-hitting against 0.5 m targets is 600 km. Maybe the Airborne Laser could eventually hold a .25 m error circle at 600 km (1/12 arcsecond). Okay, then your sure-hitting range is 1200 km.

But now we're talking about pointing accuracies within a factor of 12 of Hubble performance. I'm not buying that for half a heartbeat.

Tony said...

Re: Raymond (some more)

WRT what you expect a brilliant pebble to do upon being radiated...

Well, we can pretty safely assume that all of your sensor and weapon frequency ranges are known, simply from my intelligence guys observing your weapons tests and space force exercises. Even on the Earth, where there is presumably more secrecy than space, that's how we get data to build threat warning sensors. So what remains is choosing what to do when a certain type of radiation impacts our brilliant pebble's threat warning sensors:

1. Just ignore it, until the terminal phase of the attack. We already know that your chances of getting hits at anything more than about 1,000 km aren't all that great, or

2. Start to maneuver -- the time the enemy spends chasing you around, trying to refine his solution, is time he's not spending on other projectiles; if he stops chasing you, stop maneuvering, or

3. Start up your sensors and start actively homing; the enemy really can't ignore you then.

In any case, combining the actual likelihood of getting killed outside of terminal homing range and the likelihood of wasting enemy time on trying to get killing hits, there's not really a bad answer, just possible less optimal ones.

Anonymous said...

Krakon,

Which leads to the sensible removal of the reaction chamber and the design of an external pulse drive. Terrawatts without the hassle.
==================

Actually I was wondering about even melting compnent parts with an external pulse drive.

40% waste energy in the form of neutrons is a big complicated design chalenege when you are talking about TW.

(SA Phil)

Anonymous said...

(SA Phil)

Hmmm, how does that work with the Laser accelerated missile?

a GW Laser imparts how much thrust to a 1 KG object?

Anonymous said...

ElAntonius said:"However, this brings an additional question...if the objective is to saturate targets in the EU, why are they sending a constellation at all? KKV saturation will do, I think...they're better off trying to saturate point defense by sending more KKVs per ton than they are trying to send equivalent ships and trying to win orbital control."

The answer to that would be political; manned ships send a message that robots don't; manned ships can tell other nations/coallitions that they are not the subject of attack; propaganda; other nations/coallitions also operate in Earth orbit and it wouldn't be politic to hang around, so a fast flyby/slingshot type mission is prefered; and last, but not lest, the embarked commander could abort (not launch weapons) if it was decided that a propaganda victory instead of an actual attack.

As far as I can tell, the EU wins even if both sides destroy each other, or if the Mars ships are mission killed, regardless of damage to the EU ships, if both sides merely expend all of their secondary weapons and the Mars ships have none left over to counter any defences the EU still have in orbit, then Mars loses; so, yes, the defenders have the advantage. If the Mars constillation has better EW or they have even a tiny advantage during the second, laser-only, phase of combat, then the Mars ships might win. Probably not, but maybe.

Ferrell

Milo said...

Ferrell:

"Both groups reach 30 Kps for a closing velocity of 60 Kps;"

I think "flyby intercepts" are a horrible idea. You get one brief window of opportunity to take out the enemy and then go hurtling past, unable to do anything to mop up the inevitable survivors.

You know the battle is impending long in advance. You're going to try matching speeds. Not stepping on the proverbial gas pedal.

David said...

Ferell;

In actuality, wouldn't the Northern Barsoomian Intelligence service mearly send some agents to infiltrate the EU, as either agents provactaures or as "wetwork specialists"? It seems to me that in any plausable midfuture scenario, where we have colonists harvesting MacGuffinite, it would be more likely that covert operations and espionage would be more effective that out and out conflict, precisely because any conflict would be so resource intensive that it would not be worth it.
A small colony, with few citizens, and relatively few resources, would not be willing to committ to a large agressive action against a major terrestrial power. However, bullets are cheap, and a good sniper can change the course of history, just by hitting the right guy at the right time.

Scott said...

In other words, I remove all the charges used to accelerate the missile, remove the nuclear fuel, put is all in one big bomb with a SINGLE case and a SINGLE igniter (the orginal would do). It would be a small charge, and the rest of the nuclear fuel as a second stage who's power just goes up with how much more fissiles you put in it.

That's not how nuclear bombs scale at all.

Byron, I have to cite something opensource when I make statements like that, and did specify “designed to carry”. I honestly have no clue how many warheads per bird, and don't care. The answer is 'many' with a much larger scorched area than you'd get simply by adding all the yields together.

Raymond, I assume that you'd see highly-enriched uranium, like a submarine's reactor core, and no plutonium-burners in space, unless something about Pu-burners makes them better to operate at those obscene temperatures (1600-2000K).

Raymond said...

Scott:

A bunch of the designs I've seen use U235 - I haven't seen any which use U238 nor any plutonium isotopes. Gaseous U235 in uranium tetrafluoride seeded with potassium or sodium ions and mated to an MHD generator is my preferred design for fission-electric; you can get the gas core temp up to 4000 K before the generator, and over 2000 K after, meaning you can run your radiators at a crisp 1590 K. Low mass, high specific power, few moving parts (the gas can be moved and compressed by EM pumps, and the MHD is solid-state) and wicked cold-side temp (which drastically cuts down the required radiator size).

If you go with liquid-core or gas-cooled solid core, you can either use U235 or thorium (which changes to U233 under neutron bombardment). In general, the higher-temperature designs need less enriched uranium and produce fewer long-lived transuranics. (And frankly, these are reasons to adopt the Gen IV designs quickly for terrestrial power production.)

Thucydides said...

I am pretty sure that the amount of overkill was established a long time ago in one of the space war threads, which makes your numbers somewhat. suspect, Ferrell.

To overwhelm a ravening beam of death requires thousands of KKV's, even a fairly modest laser will need to be swarmed by several hundred, so your fleet will need to be heavily reworked to carry huge numbers of KKV busses and brilliant pebbles. As noted, there is a need to double up since after fighting past the intercept phase you still need to have resources on hand to attack the target...

Anonymous said...

(SA Phil)

If you need the plutonium for your weapons though you can develop the plutonium economy -- especially if you have many times the number of active reactors than we do today.

Nuclear Electric vehicles imply you have recovered from the Atomic fear/ backlash that currently grips modern civilization.

Plutonium is very useful for Nuclear weapons since it requires something like 1/3 the amount to get a critical mass quantity.

It is also useful for smaller nuclear reactors for the same reason. Which you would expect would be quite in demand for smaller spacecraft.

Anonymous said...

(SA Phil)

I am still having trouble with the idea that a GW laser can provide 100G's of thrust for a KG missile.

According to Atomic rockets a 1GW Photon drive would give you about 3.33 Newtons of trust.

Which seems a bit anemic to get 100G accel.

Unless we are considering an ablative propellant or something - but at that point you don't get substantial thrust for very long.

If you did you would use ablation as your main spacecraft drive.

Raymond said...

Tony:

Numbers. Whee. Excellent.

So:

- I mentioned earlier a 100 MW laser and a 10 m mirror. My preferred configuration is in fact two primary mirrors on independent mounts and a number of secondaries (let's say four). The area of a 10 m mirror gives two mirrors of 6 m diameter, and four of 1.32 m. If you'll allow me to stretch a bit, let's say two primaries of 6.5 m each, so I can use James Webb numbers fairly directly. (This also fits nicely with the 1.32 m secondaries, as the JW segments are 1.32 m flat-to-flat.)

- I'll keep the 100 MW laser as a single driver (or a number of modules in series, whichever). I'll be firing 5 MJ pulses, each 10 ms long, at 20 Hz - roughly equivalent to 2 kg of TNT per shot, and I'll come back to the pulse cycle in a bit. I'll be using a 500 nm green laser, which is a) within current tech, and b) lets us use optical mirrors for the beam path (no grazing mirrors required like with UV).

- I'm going to use target acquisition times of 1 s per target in an incoming pebble cluster - quibble if you will, but you'll see in a bit why I don't think that's unreasonable. I'll also be using the primaries in alternating-fire mode, so while one mirror is firing, the other is acquiring its next target. This is one reason I like dual primaries (another being the extra defense against multiple incoming vectors, which I believe would be an important tactic).

- I'm going to be quoting quite a few numbers from the Webb specs here:

http://bit.ly/e8225Y (Gardner et al.)

- Quibble as you like with whether the Webb specs will work in practice, but I think they're reasonable, and serve as a good approximation of an n+10 generation military laser mirror. The instruments on board go from 0.6 microns to 28 microns - this is close to my laser's 500 nm wavelength, so we can probably extend the upper range a bit without stretching anything too far. The infrared camera has a 32 millisecondarc-per-pixel resolution, which should be just fine for target tracking at engagement ranges.

- Webb is supposed to get diffraction-limited resolution. Raytheon and Northrop Grumman are claiming beam quality of 3.0 or better (I saw 1.5 claimed somewhere). While 1.5 is probably sketchy for a first-gen laser, we're talking n+10, so I'll use 1.5. Net result: approximately 1.5 times diffraction-limited beam spot size.

- Webb has a stationary target pointing accuracy of <5 milliarcsec and moving-target <30 milliarcsec: "JWST will be capable of relative pointing offsets with an accuracy of 5 milliarcsec rms, which will enable subpixel dithering and coronagraphic acquisition. Absolute astrometric accuracy will be limited to 1 arcsec rms by the accuracy of the guide star catalog.
JWST is expected to be capable of moving object tracking, at rates up to 30 milliarcsec s−1 relative to the fixed guide stars, although some degradation of the image quality may occur" (Gardner, pp 586).
I'm going to be pessimistic here, and use 100 milliarcsec for a moving target, giving a sure-hit distance of 1000 km for a 0.5 m target (by your previous numbers).

(Cont'd)

Raymond said...

(Cont'd from previous)

- At 5000 km range, the round-trip time is 34 ms. For the 50 ms pulse cycle, this gives 24 ms after the laser pulse ends to track to the next expected location and enable lidar function in the sensor (here I'm assuming separate beam paths for incoming and outgoing light, so as to eliminate physical switching; this is doable according to Luke, and I have to reason to suspect otherwise). This also gives 16 ms after the leading edge (6 ms after the trailing edge) of the returning pulse to complete the sensor loop - if returning light of the proper wavelength is detected, there was a hit. Combined with the infrared sensor, this gives a proper closed-loop transfer function to control the next shot. Given how much can be computed in a few milliseconds with even modern computers, I don't think this is unreasonable.

- At 5000 km, the spot size is 70 cm (with the beam quality of 1.5). Going by Luke's laser calculator at http://bit.ly/gu60tr and treating it as a heat ray, a 5 MJ pulse lasting 10 ms is the equivalent of a 500 MW beam, and this pulse will strip a tenth of a mm of carbon armor (drill rate 1.08 cm/s per pulse, net 2.16 mm/s for a full 20 pulse cycle). It will also cause flash heating, blind sensors, and could easily damage laser mirrors.

- At 1000 km, the spot size is 14 cm, and the drill rate for carbon armor is 2.73 mm/pulse (5.46 cm per full 20-pulse cycle). Given the pointing accuracy is basically sure-hit at this range, you would have to have substantial armor on the pebble to withstand that damage.

- At 500 km (100 sec to impact), the secondary mirrors can engage - and here I can assume half the pointing accuracy and still get sure-hit. Spot size is 35 cm, and given a gatling-style rotation between the four mirrors, this gives five pulses per secondary per second. Each five-pulse cycle drills 2.18 cm of carbon armor.

- At 100 km, the secondaries get a 7 cm spot size and drill at 5 cm per five pulses.

- I think all this should be enough to get your hundred pebbles.

Raymond said...

(Addendum)

It may be useful, after engaging each incoming kinetic once, to insert a dodge period of a hundred seconds or so. Even with a milligee drive, this should get enough delta-v to require still-active kinetics to correct their course to maintain intercept. This can also be used for target reacquisition (passive infrared, active lidar, active radar, or all three) to provide updated trajectories - pebbles hit but not disabled may still have altered trajectories due to outgassing of their skin.

Raymond said...

SA Phil:

I think the idea is ablative propulsion; this is the same idea as laser propulsion for getting to orbit. The laser provides an external power source to heat propellant, and if you use an ablative thrust shell, you can get a higher specific impulse than chemfuel alone.

Anonymous said...

(SA Phil)

That wont really be torch missile level performance though?

Since it will be a very limited amount of propellant?

Anonymous said...

(SA Phil)
You could probably carry some water to use as reaction mass for "high accel" kinetic Dodging

Use some of the heat produced by the laser.

It would also increase your cooling capacity.

Raymond said...

SA Phil:

Depends on the missile size and the laser power. A 100 MW laser driving a 100 kg projectile gets a whopping 1000 kW/kg to start, which is an order of magnitude better than the Shuttle with SRBs at liftoff.

Rick said...

Jollyreaper -

I'm only scared of people who can convince themselves otherwise.

This was always my concern with Star Wars (the program, not the movie) - that in the hands of a dangerously naive political leadership it would become a high tech 'ghost shirt,' working out no better than the originals did.

Rick said...

Well, it turns out that military grade pointing precision for guns is generally specified as 1.0 mils. 0.5 mils is considered high precision.

What are the factors that limit artillery precision? At least one that I can think of - uncertainty/variability of atmospheric winds - has no analogy for laser operations in space.

An uncertainty of 1 knot in average crosswind speed along the trajectory would pretty much correspond to 0.5 mils of uncertainty for shells with velocity on order of 1 km/s.

As a more general observation, my earlier discussions have (deliberately) pitted 'ideal' lasers against 'ideal' target seekers. If real life proves much tougher on one than the other, move the balance of weapons slider accordingly.

But it would be the least of surprises if the real world performance of each is degraded about equally, leaving the balance broadly unchanged.

Thucydides said...
This comment has been removed by the author.
Thucydides said...

Laser weapons will be developed in a space scenario because of the vast advantages over more conventional weapons. The process is already well underway on Earth today, with an entire zoo full of laser weapons mounted on trucks, ships and aircraft. These have demonstrated kills against things as small as incoming mortar shells to as large as old booster rockets as part of the development and validation process, so by the time anyone get around to wanting a space laser, the art and science will be well developed to deal with tough working environments like the ocean or pulling "g" and atmospheric turbulence on an aircraft.

Given the giant range advantages and the speed of engagements, laser weapons will be able to open and break engagements at their crew's discretion. If laserstars are part of my constellation, I can open up with a few at "scorch" range to dazzle enemy sensors. If the benchmark range for "Kill" is 3000km, "Scorch" could be 10X farther away. Lacking an SFnal ravening beam of death, I could use the window of blinding to send my own KKV busses out. As an added bonus, the reflected laser energy and heat load will assist my weapons in finding their targets.

Things get better as the range closes. Assuming the enemy isn't trying to engage in a scorch or eyeball frying contest, the beam is illuminating the oncoming cloud of KKV's, giving my fire control center better data for the upcoming engagement. When the enemy KKVs reach laser kill range, they will have been plotted and possibly atritted by various means. I still have the time to slew mirrors, go through the threat tree or boost my ship before the ship and launcher get in range of the KKVs.

Since there are multiple platforms in a constellation, the laserstar is also receiving cooperative targeting data from many platforms, providing a 3D target solution for the oncoming cloud of KKVs. Multiple laser platforms in the constellation would provide even more protection, including combining beams on single targets at scorch ranges to raise the energy level to kill well outside the nominal 3000 Km kill range.

The only sure means of destroying the laser platform is to send such an overwhelming number of KKV's that the laser cannot deal with them all in the allotted time, or have a much more powerful laser of your own. In the plausible midfuture(tm) the primary mission of the laser will be to protect the constellation from enemy KKVs. When it is possible to generate ravening beams of death with ranges out to a light second then lasers will become offensive weapons as well.

KraKon said...

"I am still having trouble with the idea that a GW laser can provide 100G's of thrust for a KG missile."

It's not a photon drive...it's a Laser THERMAL drive (it's the LT in LTAWS). The laser heats up something.
I agree with the fact that photon drives are absolutely useless for anything without several TW/kg.

"According to Atomic rockets a 1GW Photon drive would give you about 3.33 Newtons of trust.

Which seems a bit anemic to get 100G accel."

Actually, you can get more than that, minimum double to triple. You bounce the beam back and forth between emitter and target. Second bounce gives a 2GW pulse, third 3GW...then you start losing to reflectivity and spot size issues.

"Unless we are considering an ablative propellant or something - but at that point you don't get substantial thrust for very long.

If you did you would use ablation as your main spacecraft drive."

Ablative rockets have pitiful exhaust velocity. 10km/s eV is supposed to be hopeful, and that doesn't lead to 80km/s intercept velocities.

The LTAWS missile has to be as simple as possible, so as to be cheap and compete with mass dumping of chemical missiles.

It has only three parts: A propellant dome with a tunnel cut through it, a preprogrammed hydrogen pump and a permanent 8 telsa magnet.

During the acceleration phase, the pump squirts hydrogen pulses several hundreds of times a second. Each pulse is first ionized then subjected to a 4GW blast of laser energy (laser pulse in the MJ range, hydrogen blasts in the 10's of grams). This causes it to explode in all directions...but the magnet creates a magnetic nozzle (the magnet is tubular, with the chamber inside it) which provides 40km/s exhaust velocity.

Plasma which escapes the nozzle upwards heats up the hydrogen tank and increases its internal pressure. The pump then has to only open a timed hole in the tank for hydrogen to be released.

The missile has a mass ratio of 10. The magnet (which doubles as impactor) weights along with the pump and tank 10kg. 90kg of hydrogen is contained, for an initial mass of 100kg (I haven't looked into armoring yet but it will be around 5kg, with 500m/s rotation rate from 2000km. Haven't factored it in yet).

The drive is 50% efficient; the waste heat is supposed to leave with the plasma and the heated hydrogen slush.

This gives us 100kN of thust, so acceleration ranges from 100g to 1000g.
The mean acceleration is 550g. This allows us to reach 80km/s in 14.5s as a maximal velocity. The good thing is that this missile has 92km/s dV, so 12km/s are left over for it to maneouver near the target at near 1000g.

Questions? ;)

KraKon said...

"That's not how nuclear bombs scale at all."

Of course that is not sensible as a nuclear bomb design, but it is a good example of how to use the ORION interceptor's fuel more efficiently.

On scaling...the teller-ulam design (which I have adopted for my nuclear pulse drive) have a small imploder as a primary charge, and a huge in comparison mass of fissile fuel at the other end of the chamber. I haven't seen anywhere that the second charge is restricted in size to being proportional to the ignition charge. If there is a limit, then I'd include a third, fourth stage...maybe not as the Tsar Bomba uses a single stage, and still gets 150MT.

I do know that several mid-range charges are better for diverting asteroids or vaporizing ships and the like, but a single large explosion lets me compare kinetic energy vs fuel energy easily in the ORION example.

KraKon said...

"- I think all this should be enough to get your hundred pebbles."

I guess these brilliant pebbles are inert balls of bang, right?
Or are they fitted with sensors and a dedicated drive?

In the first case...spin it. It is a sphere, so you can make the hemisphere (especially the band covered by the laser spot) rotate rapidly along any axis.

Say the sphere is 30cm in diameter and made of carbon.
Using means and approximations:
The damage varies between 2.16mm/s to 5cm/s;
mean penetration rate is 26.08mm/s
The basket ball of death (BBOD!) takes (assuming 30km/s) 167s to cross the No Man's Land.
We don't want the ball to lose more than 50% of its thickness.
This requires a mean penetration rate of 0.9mm/s...
How fast do we have to rotate this thingy?
Mean spot size is 38.5cm. We need a reduction factor of 26.08/0.9 = 29.

29*0.385 = 11.2m/s

Wut. A ball spinning at 11m/s facing the target's laser can survive the two and half minute onslaught of all your defensive weapons? And I thought that I had to go into shifting the band covered by the spot to start grinding down a new band, divinding the total penetration by the wave's survival rate (you can afford 80% of your wave to die and still get several missiles through. If you accelerated 100missiles, and only 20 go through, you have still obtained 198GJ on target), putting BBODs one in the shadow of the other, and such and such...

However, it is unlikely brialliant pebbles are inert and unpropelled. They'd likely have at least chemical thrusters that ensure they are able to follow the target around as it dodges. Each pebble can be mission killed if it loses all its thrusters...the thrusters could also be held inside the mass, and spun around, while still ensuring maneouverability through well timed bursts.

Another difficulty is actually getting a 20kg BBOD, in batches of 100, up to 30km/s...

Anita said...

Today is the 50th anniversary of the first human space flight.

Salute Colonel Gagarin.

ElAntonius said...

Krakon: 30km/s is fairly impressive for 20kg. I could see it if the launcher did most of the accelerating and then tossed the brilliant pebbles out a window, but I don't think you're going to see any sort of significant maneuver capability on the BBODs.

A Sidewinder missile weighs 86.2 kg (with a 9.4kg warhead) according to the Wikipedia, and is designed for a speed of Mach 2.5. That's about 0.85 km/s in air. Even
knowing that number would be significantly higher in vacuum, I don't think we're going to see space kinetics weigh anything less than that if we want them to have propulsion.

And the Sidewinder is the simplest, shortest range missile in use today.

So we're talking about having to use a first stage booster for our BBODs...what do we need to get 20 tons up to 30km/s?

Raymond said...

KraKon:

I was assuming the same 5 km/s incoming velocity Tony did earlier, which gives 1000 s, not 167.

KraKon said...

Yes, 30km/s is high, but that number was thrown around here somewhere...Probably the fast flyby tactic where the missile bus' dV contibutes little to the warhead's velocity.

I don't really like the concept of brilliant pebbles (why are they brilliant?) but I'll work with the assumption that they're a viable kinetic energy delivery system, against Raymond's laser defence.

The Sidewinder missile, from your stats, has a mass ratio of 10.17
This gives it a dV of around 2.3x its exhaust velocity.
Around 10km/s then. It does have however around 10g+ acceleration.

However, the BBODs don't need as much. All they have to do is match the target's acceleration during the whole transit (or be able to match it with a burn that otherwise takes the target minutes to achieve).
Chemical thrusters are also extremely scalable at the low end so:
The target has a spherical cow acceleration of 1 milligee. The BBOD takes 167s to reach it, meaning the target puts out 1.67km/s during the BBOD's transit.
The target can accelerate in any direction, the BBOD must be able to do the same. 6 thrusters are required, facing all axis. The dV requirement of the BBOD in any direction has to be slightly higher than that of the target since adding vectors gives a sum lower than that of the two original vectors (there is a possibility of getting away with 3 thrusters only, but I don't want to calculate that).

A chemical thruster, whatever size, can easily be made to achieve 4.5km/s in eV. Mass ratio to obtain 1.67*6 km/s dV is: 9.6

Now we have the option of
a)Reducing the BBOD to a carbon shell massing 2kg, containing 18kg of solid monopropellant inside.
b)Increase the mass of BBOD by a factor of 10
c)Cheat and find ways to reduce the dV required.

Option A leads to a shell only 0.25cm thick. Since with previous parameters the laser went through 15cm,you'll have to accept either one BBOD surviving out of 60, a wave 60 times larger, a faster rotation rate (likely), a secondary thruster system to shift the spot left and right (likely) or a faster closing velocity (by a factor of 60...ouch...unlikely).

Option b is harder. You can use the same tactics as above, but armor has lower thickness and it is very hard to get the damn thing up to speed (hey, its 200kg per submuntion). Actually, this is a counterproductive option as larger mass means larger volume therefore the BBOD is easier to hit and detect....meaning more armor and more mass...

Let's try option C-the sensible thing.
Previously, I stated that you need a thruster per direction. Not true. You can skip the thrusters along your axis of travel because the target's acceleration along your direction of travel does not reduce hit probability, just increases or reduces travel time by +/-4 milliseconds.
4 thrusters...2/3 of the previous dV required...mass ratio reduced to 4.4; the armor, if we conserve the same mass, is 4.5kg or 4.5cm thick.
I'd say not too bad. One BBOD survives out of 3. On-target impact energy is still a non-negligible 16.5GJ. Break out the BBOD survival tactics and you've got yourself a target-seeking 20kg (4.5 upon impact) basketball of death.

To get the bus up to speed from 0 is hard.
Using chemicals (generous 6500m/s eV) you'd need a mass ratio of 100. Even Saturn V didn't have that much, and it means our bus will weigh around 240 tons( with bus 20% of warhead mass).
Using a nuclear electric thruster, coupled to a 0.3MW, 300kg reactor providing 30km/s exhaust velocity, we'd need a mass ratio of 2.72, or a bus mass of 7.5tons. Perfect mass wise but it needs a run-up distance of 91 million km (?!!).
Trying a beefier 1 ton 1MW reactor, we'd have a bus massing 10.7 tons but still requiring a run-up of 39 million km.
Ditch both drives.
Give up on 30km/s and accept a more realistic 5km/s, 6x attrition rate than above!

Tony said...

Anita:

"Today is the 50th anniversary of the first human space flight.

Salute Colonel Gagarin."


"Poyekhali!"

jollyreaper said...

One solution for people who want to continue to do WWII in space, why not just ditch the space part?

Pretend that the whole Philadelphia Experiment works. You've got parallel Earths discovered at the end of WWII. You've got Earth2 with the Nazis winning and they've discovered they can move between the worlds, too. You've got a whole new planet to fight on with a familiar new enemy, plausible tech, and all the tropes you like. Big battleships, zoomy manned planes, manned turrets, lots of flames and explosions. And the only tech pulled from proctological regions would be the mcguffin resonator that allows ships to move between worlds.

Byron said...

jollyreaper:
Please don't encourage people. There was a perfectly reasonable explanation for what happened. See here.

jollyreaper said...

Please don't encourage people. There was a perfectly reasonable explanation for what happened. See here.


Imagine how much of a bore speculative fiction would be if we stuck only to the perfectly reasonable explanations. The whole point of the exercise is going with the outlandish explanation and then treating it as realistically as possible!

Byron said...

I'm leaving before Tony sees that.

Tony said...

Rick:

"What are the factors that limit artillery precision? At least one that I can think of - uncertainty/variability of atmospheric winds - has no analogy for laser operations in space."

Just off the top of my head:

* crosswind velocity
* crosswind direction
* air temperature
* rotation of the earth
* imprecision in determining target location
* imprecision in determining target altitude
* imprecision in determining own location
* imprecision in determining own altitude (not applicable at sea)
* imprecision in determining target ship/sircraft speed (only applicable at sea)
* imprecision in determining target ship/aircraft heading (only applicable at sea)
* imprecision in determining own ship speed (only applicable at sea)
* imprecision in determining own ship heading (only applicable at sea)
* correction for roll (only applicable at sea)
* correction for pitch (only applicable at sea)
* variations in propellant stock
* variations in projectile stock (mass & shape)
* variations in barrel wear
* imprecision in fire control sensor alignment
* imprecision in paralax survey of fire control sensors WRT gunnery computer position (only applicable at sea)
* imprecision in paralax survey of weapon mounts WRT gunnery computer position (only applicable at sea)
* imprecision in aligning weapon training gear WRT reference direction or ship longitudinal axis
*imprecision in aligning weapon pointing gear WRT reference direction or ship vertical axis

Not all of these have parallels in space. But many do. Certainly errors can be made in determining target position and movement and own position and movement. Even with lasers, a few meters position error or meters/second velocity error can make the difference between hitting and missing. Also, lasers rely on mechanical pointing and training aparatus of one type or the other. That can lead to all sorts of errors. And while lasers in space don't have meteorological challenges, they have purer physics challenges. Rotating a beam pointer one way rotates the ship the other. This has to be physically compensated for in some way. Also, the shorter the targeting interval one allows for, the jerkier the pointer and training gear gets, and the harder you have to work and/or the longer it takes to settle out the induced vibrations before shooting.

"As a more general observation, my earlier discussions have (deliberately) pitted 'ideal' lasers against 'ideal' target seekers. If real life proves much tougher on one than the other, move the balance of weapons slider accordingly."

I'm just trying to groundthe discussion in reality. Achieving the high precision necessary for long range laser engagement is a hard task that might not be workable anytime soon, or even well into the future. It's not just an engineering detail that will conveniently work itself out.

"But it would be the least of surprises if the real world performance of each is degraded about equally, leaving the balance broadly unchanged."

I would bet on kinetics all the way to the bank. One of the big reasons thataircraft delivered ordnance and guided missiles have supplanted gunnery in naval combat is that homing on a target gives you so much more scope for accuracy than relying on ballistics.

Rick said...

Anita (and Tony) -

Thanks for the reminder. "Poyekhali!" indeed!


I think jollyreaper's comment was more than a bit flippant, not reflective of serious belief in the 'Philadelphia experiment.' The truth is that an awful lot of space war discussion and fiction is basically World War Two in SPAAACE !!!

Tony said...

Byron:

"Um, no. That's a red herring. I said that if said lasers exist, then 5 km/s kinetics are useless. Do you disagree with that, or not?"

It's not a red herring at all. It's precisely the point I am trying to make -- you assume that technical capability and combat effectiveness are the same thing. They are minfestly not. Just because you can designe a laser to generate enough power to be effective at 30k km, that doesn't mean you can hit a target with it.


"And why can't they be detected?"

Because until they generate heat cooling down their homing sensors, they are small, cool, and could be made to reflect light in the same general way as random hunks of rock and ice do. And we know there's al ot of junk in the soda can to basketball size range whizzing around in interplanetary space.

"I'll have a fairly good idea of where they are, as you're proposing using missiles to launch them. That tells me where to look. If there are no targets in range, I sweep with my laser in lidar mode, and when I pick them up, I shoot.

For that matter, SBX has a range against a baseball-sized target of close to 3,000 km. I know it's heavy, but it's current technology, your projectiles will be bigger, and it's not designed for space. I don't see this as insurmountable."


Possibly. But so what? It's not likely you'll get too many hits until the attacking projectiles are a lot closer.

WRT SBX, when they can scale the radar antenna down from 1800 tons to maybe 1.8, then it would be a viable spaceborne tactical combat sensor. But i wouldn't hold my breath, because its size and the number of elements it contains has a lot to do with its discriminatory powers.

"By your logic, any story that incorporates it isn't plausible. That's my point."

Any story that incorporates it for more than it has already been able to do isn't plausible, yes. Any story that incorporates chemical rocketry to lift thousands of tons for a single space weapon isn't plausible either.

"By high-speed I mean in the 30 km/s range. I don't see chemical missiles getting above 5 km/s or so, which is too slow in a universe of .1 ls lasers. (I know you don't think they will exist. However, if they do, chemfuel missiles are out.) That sort of velocity is only achievable with a miligee drive, which can't reach those speeds on a tactical timescale. If you're outlawing the lasers, the picture changes."

But I think 5 kps is tactically viable at a few hundred to a few thousand kilometers, which is a much more believable range of space combat in the plausible midfuture. To put it as simply as possible, you believe in magic and I don't.

"But they have to have those shots. Your argument is the same as saying that carriers are obsolete because enough ASMs can take one out. But ASMs are far better at sea denial than sea control, and the same applies here. Missiles can work, but I question them being powerful enough compared to lasers. I could be wrong, but I also could be right."

You could only be right if lasers were capable of levels of accuracy and speed of engagement that frankly strike me as fantastic. And before you go there, I was a big believer in precision guided munitions and GPS long before a lot of people even knew what those were. But there's a difference between solving clear engineering problems and hand waving away clear physical limitations.

Milo said...

Jollyreaper:

"One solution for people who want to continue to do WWII in space, why not just ditch the space part?"

...Because then there's no space?

Anonymous said...

(SA Phil)

I am wondering if the targetting problems are getting a bit overblown.

If you are using a visible light laser to hit something AND you are using Visible light in your targetting

A space laser is going to work largely like a telescope.

Since if you can see your target with your optics, you can also shoot the laser at the same image.

Any bumps will move the image also.

Its not the same as a ballistic projectile.

jollyreaper said...


I think jollyreaper's comment was more than a bit flippant, not reflective of serious belief in the 'Philadelphia experiment.' The truth is that an awful lot of space war discussion and fiction is basically World War Two in SPAAACE !!!


Correct. And I think that you do less violence to the story setting to just have parallel Earths and have the battle fought across them than trying to get spaceships and space polities to behave like terrestrial analogues with similar forms of warfare.

I'm not dogmatic about the fiction I like and I can appreciate a variety of approaches. I like hard SF, semi-firm SF, squishy SF, mildly speculative fiction, wildly speculative fiction, and everything in between. My only concern is that the story is internally consistent, coherent, has well-drawn characters whose motivations are either made plain or are murky by intent rather than poor writing and, most of all, the read is entertaining.

jollyreaper said...

Case in point, there was an 80's series called the Seventh Carrier. It's about the seventh carrier the Japanese sent to attack Pearl Harbor that was lost to history. Turns out there was an Antarctic base it got iced in at and was trapped until the 80's. The carrier then went and completed the attack and right after that the Chinese managed to launch particle beam weapon satellites that would shoot down any jet aircraft or missile and thus suddenly the old carrier is the most powerful weapon left usable on Earth. And now all the third world militaries with their old kit become valuable and the US is scrambling to reactivate all the old prop jobs at the boneyard.

Now, what would be more plausible, just opening up a planetary portal in 1950 so you can have your second chance at WWII or all that I just typed above? lol And the Seventh Carrier scenario for all its heart-clogging cheesiness is still more plausible than a lot of WWII in space scenarios.

Anonymous said...

(SA Phil)

Id go farther than that Rick, I think there are several people who prefer hard SF that also want to fight the Cold War/World War 3 in Spaaace!

Tony said...

Re: Raymond

Sorry, but I don't believe in space telescope levels of precision for combat systems. You've got beam pointers jerking around, alternately heating and cooling mirrors (so probably active mirror cooling and/or adaptive optic actuators, both inducing vibrations), maneuvering, Whipple shields getting hit with fragments of whatever, powerplant vibrations, coolant system noise, etc.

Also, the party initiating the kinetic attack may not need to even put highly sensitive sensors on the projectiles. Just illuminate the target with a pulsing IR laser from a safe distance. Of course, there's a target ID code embedded in the pulse. So now the projectiles can have less sensitive sensors, and they are that much harder to decoy, because they'r only homing on something reflecting in the right frequency and strobing the right target code. (That's straight from laser guided bomb tech, making it 40 year old technology already.)

Tony said...

SA Phil:

"I am wondering if the targetting problems are getting a bit overblown.

If you are using a visible light laser to hit something AND you are using Visible light in your targetting

A space laser is going to work largely like a telescope.

Since if you can see your target with your optics, you can also shoot the laser at the same image.

Any bumps will move the image also."


First of all, using the wepaon otics for fire control has some built-in problems. They may not be insurmountable, but the solutions also may not be refinable to a point that it makes sense.

If a solution can be found, the image will still be jiggling constantly across the targeting sensor. At longer ranges one has to wait for that jiggling to settle down -- if it ever does -- before shooting.

jollyreaper said...


"One solution for people who want to continue to do WWII in space, why not just ditch the space part?"

...Because then there's no space?


I don't think space is all that important for most of those settings. They're not really using the space parts for anything really mind-bending. If the story they want to tell would really work better with ships sailing around on terrestrial seas, why not do it there?

The techno-thriller writers ran into this problem at the end of the Cold War. They wanted to tell big, world-spanning war stories but were at a loss for enemies to pit against the US. Now the obvious idea would be to push into alternative histories but I guess that's just too much world-building. So instead we get drug smugglers fielding their own private air forces using top Russian kit, Japan suddenly becoming an expansionist power again, weird fantasies involving China, all sorts of stuff that's just viciously bashing plausibility about the head and neck.

Like I said, I love hard SF and I love outright fantasy. Some people think they're trying to tell a hard SF story but it would be a lot less convoluted if they'd just admit to being fantasy and openly embracing it.

jollyreaper said...

Like I've said before, my bias is towards a logical set of consequences stemming from the outlandish assumptions behind the setting. Is magic real? Ok, how about necromancy? Could wizards raise up something akin to a Haitian zombie, undead servants? If so, how does this impact the labor market? It would probably be even more disruptive than with living slaves. The freeman would become economically marginalized. The zombie-owners would have little need for them. Except wait, what's the service life expectancy for a zombie? Oh, less than a decade even with proper care? Where are fresh bodies going to come from? Does the zombie economy make sense? Impossible to rebel combined with unceasing work but weighed against an inability to learn post-mortem and a short service life and the understandable reluctance of the living to be turned into zombies. But is there a short-term advantage in converting to a zombie economy? Yes? Then here we have a perfect recipe for conflict. The empire is based on slavery. There's a constant fear of slave rebellion. The necromancers convince the landowners to convert to zombie labor. The slaves are zombified and landowners see a huge increase in productivity. The practice spreads across the empire. Some living slaves are kept as breeding stock but it becomes clear that the fresh slaves cannot keep pace with the demand for fresh bodies for zombification, plus there's little incentive for these slaves to learn skills because they know they're destined for an early undeath. So now the empire is forced to go to war with neighboring nations for fresh bodies.

jollyreaper said...

That really strikes me as a sound premise for a story since you've got a few fantastic assumptions and then everything flows logically from there. The inherent contradiction of the economy is what drives the inevitable conflict and the greed and short-term thinking implied there has the proper ring of authenticity.

Now, could you do that story as scifi instead? I don't think so, at least I can't think of a way. You're basically talking about borging the humans instead of reanimating them and that's talking about some really sophisticated technology, decades ahead of where we're at now. And that far in the future, why use borgified humans instead of robots? Borgified humans in a scifi version of this strikes me as less plausible than zombified humans in a fantasy setting. Subjective POV, of course.

If you just want to run with the idea of what happens to a marginalized labor force when there's no more need for their services, you could set it in a fantasy land where Mickey Mouse gets his Sorcerer's Apprentice brooms to cooperate and builds magical automatic factories or you could set it a few decades in our own future where robotics has become affordable enough to drive even sweatshop laborers out of work. But if you really want to have disaffected labor and the horror element of zombies, then the fantasy line would be the way to go.

Tony said...

jollyreaper:

"The techno-thriller writers ran into this problem at the end of the Cold War. They wanted to tell big, world-spanning war stories but were at a loss for enemies to pit against the US. Now the obvious idea would be to push into alternative histories but I guess that's just too much world-building. So instead we get drug smugglers fielding their own private air forces using top Russian kit, Japan suddenly becoming an expansionist power again, weird fantasies involving China, all sorts of stuff that's just viciously bashing plausibility about the head and neck."

And relatively few SF fans want to read that stuff either, even in an SF setting. It's part of that 90% of everything that's published that is pure crud.

"Like I said, I love hard SF and I love outright fantasy. Some people think they're trying to tell a hard SF story but it would be a lot less convoluted if they'd just admit to being fantasy and openly embracing it."

Just because you use magitech doesn't mean you're engaging in high fantasy. And, quite frankly, WWII or the Cold War in space is just as boring as fantasy. So is trying to redo Hronblower IN SPAAACE! (ahem, Mr. Weber, ahem...). I'll take suspending disbelief on hyperdrive and operatic normal space drives, but with everything else following reality as much as possible, thank you very much.

Anonymous said...

Tony,

I'll take suspending disbelief on hyperdrive and operatic normal space drives, but with everything else following reality as much as possible, thank you very much.

If you mean current day reality -

From a tech level perpective this is no different from "Cold War/World War 3" in SPaaace!


============
This latest Battlestar Galactica technology wise was a WW2/Korea/ Early Cold war in SPaaaace!

From a Softer Sci Fi / Tech level standpoint, but not froma story standpoint.


-- (SA Phil)

Tony said...

Tony:

"If you mean current day reality -

From a tech level perpective this is no different from "Cold War/World War 3" in SPaaace!"


I don't mean current day reality. I mean reality in the sense of not defying physical principles that are well understood. You may have hyperdrive, but it has to take you from here to there without defying causality. And you may have operatic levels of acceleration and delta-v, but you're still limited by physics to realistic trajectories. Even if you have drives that somehow push against the fabric of space, they still use energy and can't defy inertia. That's the kind of reality I'm talking about, not making the world static except for magitech space travel.

Byron said...

Tony:
No, you keep misunderstanding me. I should have said an effective range of .1 ls, but I thought that was understood. My statement stands.

Because until they generate heat cooling down their homing sensors, they are small, cool, and could be made to reflect light in the same general way as random hunks of rock and ice do. And we know there's al ot of junk in the soda can to basketball size range whizzing around in interplanetary space.

Not that much. I don't see anywhere close to the densities your kinetics would be at. How many probes have we lost to debris? I can't think of any. We haven't lost that many satellites, for that matter, and there's a lot more debris up there then there is in interplanetary space.

Any story that incorporates it for more than it has already been able to do isn't plausible, yes.
Nope, still not getting it. You've said that everything has to be practical for the story to be plausible. You've also said the shuttle isn't practical. QED, any story containing the shuttle isn't plausible. Thus, neither is reality. I think I'm not going to take this any farther.

But I think 5 kps is tactically viable at a few hundred to a few thousand kilometers, which is a much more believable range of space combat in the plausible midfuture. To put it as simply as possible, you believe in magic and I don't.
Nope. I believe that engineering might get better and you don't. However, that sums up the problem. I think this thread of discussion is done.

But there's a difference between solving clear engineering problems and hand waving away clear physical limitations.
And you keep confusing the two.

And leave Weber out of it. Honorverse was better than a lot of stuff I've read. He at least thought the scenario out, sometimes to a ridiculous extreme.

Jollyreaper:
I'm going to classify stuff like that as science fantasy. Speculative fiction has always struck me as absurd. Usually, it's an excuse to get rid of science, not to actually speculate about where science will take us.

jollyreaper said...


Jollyreaper:
I'm going to classify stuff like that as science fantasy. Speculative fiction has always struck me as absurd. Usually, it's an excuse to get rid of science, not to actually speculate about where science will take us.


Your mileage may vary. Everyone has their way of defining things. My definition of speculative fiction is anything that departs from hard, objective, known reality. It could be as simple as the odd twilight zone premise like a guy suddenly developing the ability to hear the thoughts of others, seeing a gremlin on the wing of a plane, etc. That's apart from stories that are completely plausible with scenarios that could really occur such as the guy surviving the nuclear war and having all the time in the world to read books, that is until he drops his glasses. Some people might say that's still speculative because even though nuclear wars are possible, they haven't happened yet.

The further afield of the normal you go, the more labels you can slap on it. Hard SF is the next step beyond mere speculation because you may include some wild concepts but they're not directly violating known physics. When you abandon known physics but try to remain self-consistent to the imaginary rules, that's fantasy. If you try to pass off the magic as technology then you're in science fantasy territory; if it's spells and conjuring magic, you're in fantasy land. And there's plenty of room for cross-pollination. Shadowrun mixed tech and magic, Warhammer 40K does the same. Urban fantasy has been really big in recent years.

The thing that I think people overlook is that they think fantasy is just about magic or impossible technologies. Really, there are a tremendous amount of bad fantasy stories without a bit of that. Their problem is that they completely make a hash of characters, motivations, and procedures in the real world. The average police procedural violates hard reality more blatantly than even the worst Star Trek spin-off does to physics.

Raymond said...

Tony:

"Sorry, but I don't believe in space telescope levels of precision for combat systems. ...."

Then we return once more to dueling assumptions (less fun than a pitchers' duel, more subjective than dueling guitars). I think slightly worse performance than a bleeding-edge space telescope is a good enough first approximation of a weapons system ten generations hence. The problems are engineering-related, not fundamental physical limitations - and given current trends of laser weapon development, we're going to have plenty of practical experience with them in the next few decades, and plenty of impetus to develop them further.

I don't think it's too much of a stretch. You disagree. I think you're essentially handwaving the whole concept away, though.

Anonymous said...

(SA Phil)

Its also possible the systems would exceed modern telescope performance(within reason).

Since the incentive to develop the technology would be higher -weapons and communications.

Two historically big dollar research areas.

ElAntonius said...

Stepping back from the lasers vs. kinetics angle a bit:

It occurs to me that antikinetic defense is going to be a top priority if we suddenly see an explosion of manned space travel (a prerequisite history of space conflict, I think).

Right now satellites are OK just dodging the odd bits of debris, but if space travel goes up by a large amount, the level of space junk is going to increase correspondingly and we are not going to be OK with eating the loss of astronauts to debris.

So in terms of near and mid future designs, most ships are going to be outfitted with having to detect/dodge/destroy bits of junk, I think, lest our LEO become completely untenable for any sort of economical travel.

And it gets worse if we introduce conflict in orbit, which I think would happen long before deep space conflict did.

Tony said...

Raymond:

"I don't think it's too much of a stretch. You disagree. I think you're essentially handwaving the whole concept away, though."

But I'm not handwaving it away. I'm giving good reasons, grounded in real world engineering principles. If anybody is handwaving, it's those that say just because it's a problem now, that doesn't mean it will be a problem in the future. Yes, we have managed to overcome a lot of engineering challenges in the last several decades. That doesn't mean we haven't run up against hard physical limitations. Soyuz and Proton, 50s and 60s technology repsectively, are still viable launch systems. And that's not for a lack of trying. The next super heavy launch vehicle the US makes will probably be heavily based on the highly advanced 1980s tech of the Shuttle. Any technology matures. Most before a lot of their initial speculative promise is realized.

Tony said...

SA Phil:

"Its also possible the systems would exceed modern telescope performance(within reason).

Since the incentive to develop the technology would be higher -weapons and communications.

Two historically big dollar research areas."


Weapons and communications tend to be a lot sloppier in application than scientific instrumentation. Penzias and Wilson were thinking the cosmic microwave background was pidgeon sh!t in their microwave before they found out it wan't. I've already pointed out that gunnery hasn't been an exactly precise art.

Raymond said...

Tony:

"But I'm not handwaving it away. I'm giving good reasons, grounded in real world engineering principles."

Sort of - except that you dismiss the possible solutions already mentioned a priori as "inapplicable to combat conditions", regardless of the merits, and regardless of technology currently in development or in limited application. That's handwaving, not good real-world engineering.

As for accuracy in general: lasers are not guns. Period. Not only do most of those accuracy factors you listed above (in response to Rick) not apply to lasers, but the other factors (related to errors in location and motion data) benefit greatly from a) the inherently more predictable motion of spacecraft, and b) the tight coupling of targeting sensor and weapon possible with lasers (at least those in the infrared and visible range).

As for using telescope specs: I don't think there's any better baseline at the moment. When it comes to the kind of optical apparatus which would be used for a large war laser, modern telescopes are the obvious starting point. As for your specific objections, go take a look through the James Webb docs - there's some good stuff in there.

Tony said...

Raymond:

"Sort of - except that you dismiss the possible solutions already mentioned a priori as "inapplicable to combat conditions", regardless of the merits, and regardless of technology currently in development or in limited application. That's handwaving, not good real-world engineering."

[A] priori? Okay, I'll wear that. But not arbitrarily -- all of the proposed "solutions" depend on unrealistic, IMO, levels of performance under combat conditions. I can't reproduce for you here all of my experience and study of the subject of military technology. If you can't take my word for it, don't buy any books I might write (In the very unlikely event I ever actually sat down to write).

Tony said...

Raymond:

"As for using telescope specs: I don't think there's any better baseline at the moment. When it comes to the kind of optical apparatus which would be used for a large war laser, modern telescopes are the obvious starting point. As for your specific objections, go take a look through the James Webb docs - there's some good stuff in there."

Scientific instruments are designed not to be used under combat conditions. There simply are no points of comparison for results achievable with scientific instrumentation and those achievable with machinery built to be used in combat.

Byron said...

Tony:
I'm with Raymond on this. Any statement you make is a basic principle, which doesn't apply to anyone else's statements. How can we know what engineers a century hence can do?
As to Hubble pointing accuracy, I don't think that's a great number. It's pointing the whole thing, and it's a number significantly below the resolution, so it's more than adequate. We don't know of anything that's been built under similar constraints to what we propose, so we have no good numbers.

As to combat conditions, what exactly are they? On the ground, you have to deal with mud, dust, being dropped, etc. On the ocean, you might have shock damage and bad weather. What is there in space?

Anonymous said...

(SA Phil)
So you design the "Scientifc" Instrumentation to work under the "combat" conditions in question.

We designed and built precision sensors to live inside a combustion chamber that messured minute(pa) pressure differences at 7000 rpm.

No one has designed Telescopes like the ones they suggest for those combat conditions because they have never been needed to be used in those Combat Conditions.

The whole "Combat Conditions" is a minomer. They are just conditions. The telescope needs to have this accuracy under whatever defined conditions.

The Instrument doesn't care if its in combat or not.

Tony said...

Byron:

"I'm with Raymond on this. Any statement you make is a basic principle, which doesn't apply to anyone else's statements. How can we know what engineers a century hence can do?"

Isn't that just handwaving? How do we know that achievable mechanical precision is going to advance all that much in the next century, or the next millenia, for that matter? SO maybe we're both handwaving -- but I'll take conservative handwaving over optimistic handwaving, because the conservative assumption has turned out to be right with aerospace technology over the past 50 years.

"As to Hubble pointing accuracy, I don't think that's a great number. It's pointing the whole thing, and it's a number significantly below the resolution, so it's more than adequate. We don't know of anything that's been built under similar constraints to what we propose, so we have no good numbers."

More handwaving. I brought up Hubble to show what's currently assumptions of near-pure physics lab conditions. For combat, you add a few ordrs of magnitude of uncertainty to the system.

"As to combat conditions, what exactly are they? On the ground, you have to deal with mud, dust, being dropped, etc. On the ocean, you might have shock damage and bad weather. What is there in space?"

Did you even read the list? Most of the things on it -- particulary sensor and weapon calibration issues, and imprecision in target and own ship position/movement -- are directly applicable to space combat conditions. Also, you have self-induced mechanical noise, which is analogous to pitch and roll on any gun-armed ship. Even the internal ballistics in guns has an analog in the behavior of optics under the physical stresses of bouncing laser beams around inside of them.

Tony said...

SA Phil:

"So you design the "Scientifc" Instrumentation to work under the "combat" conditions in question.

...

The whole "Combat Conditions" is a minomer. They are just conditions. The telescope needs to have this accuracy under whatever defined conditions.

The Instrument doesn't care if its in combat or not."


Not in an anthropomorphic way it doesn't care. But all of the physical stresses that exist in combat don't exist in scientific investigation. You can't simply exclaim, "Design for the conditions!" and automatically get results. Your sensor that measures useful differences in combustion chamber pressures inside an internal combustion engine would no doubt get results much more precise sitting on a lab bench, under static or near-static conditions.

Byron said...

Tony:
But all of the physical stresses that exist in combat don't exist in scientific investigation.
That's what I asked you. You didn't give an answer, except to look at the list. Some of those are valid, but they don't impose the physical stresses you seem to think inherent in combat. All of them fall into one of two lists: irrelevant or going to be a problem for scientific instruments too, if only to a lesser degree.
Scientists don't know exactly where they want to point their stuff, either. I'd think the laser/telescope thing would satisfy you. If not, then the computer should steer the beam onto the target. Look up how ALL tracked its targets.
The point is that there won't be serious combat stresses on space systems. They either will work fine or get hit and not work at all.

Tony said...

Byron:

"That's what I asked you. You didn't give an answer, except to look at the list. Some of those are valid, but they don't impose the physical stresses you seem to think inherent in combat. All of them fall into one of two lists: irrelevant or going to be a problem for scientific instruments too, if only to a lesser degree.
Scientists don't know exactly where they want to point their stuff, either. I'd think the laser/telescope thing would satisfy you. If not, then the computer should steer the beam onto the target. Look up how ALL tracked its targets.
The point is that there won't be serious combat stresses on space systems. They either will work fine or get hit and not work at all."


Scientists have taken decades to precisely as possible locate stuff in the sky. And that's with solidly mounted telescopes and years of calibartion data on each instrument. That alone is a departure from combat conditions with milspec instruments run by military operators. (Who are as good as they can be, but who aren't elite instrument builders and maintainers.) And I'm not exactly sure why you think all of the mechanical noise generated by an operating warship trying to maneuver, locate targets, and engage them under time pressure is somehow the same environment as a a carefully calibrated scientific instrument sitting in orbit, making adjustments at liesure, and given as much time as needed for any induced noise to settle out. It's really mystifying that you don't seem to understand that mechanical transients and imprecision in calibration are just as much a part of the combat environment as weather and incoming fire.

Raymond said...

Tony:

"Scientific instruments are designed not to be used under combat conditions. There simply are no points of comparison for results achievable with scientific instrumentation and those achievable with machinery built to be used in combat."

For a given technological level, to within perhaps three or four generations, you're absolutely right. But what constituted a high-end scientific instrument a hundred years ago can be a consumer product today (ubiquitous GPS, for example), or at least be pushed to the side by newer, much more advanced instruments (compare the Hale telescope at Mount Wilson back in 1908 to Keck or the VLT today). Or compare WWII radar to modern phased-array - if you told a radarman in 1945 about the capabilities of an Aegis system without telling him about Shannon's work or transistors, he'd probably think you were wildly exaggerating.

I use the JWST as a baseline because in terms of overall setup, it seems like the closest comparison. Segmented mirrors, each with independent actuators for angle and curvature; beryllium reflecting surface instead of glass or other ceramics; significant cooling systems for the IR cameras; and most importantly, it's a fully spaceborne package. I could've spouted off about Keck's capabilities, but even I know that'd be too much of a stretch.

Byron said...

But it's far more possible to deal with the machinery noise than it is to deal with the other things that "combat conditions" make you think of. It's fundamentally an engineering problem, not fundamental physics. And given how much progress has been made there in the past 50 years (looking primarily at submarine silencing) then I see no reason to be terribly pessimistic, particularly to the degree you are.
We're not discussing doing this 20 years from now. Closer to 200. Given that we can't predict where technology will advance, we'll almost certainly be wrong. But at least I'm willing to try, unlike you who seem unwilling to carry things beyond the near-certain future.

I'll take conservative handwaving over optimistic handwaving, because the conservative assumption has turned out to be right with aerospace technology over the past 50 years.
In aerospace, to an extent, yes. However, let's look at computers. Did anyone anticipate what we have today 50 years ago? No, and they'd have been crazy to do so. We just can't tell.

Anonymous said...

(SA Phil)

No the DSP pressure system was Designed for those conditions specifically. Well those and the computer it was attached had to work while you drove the vehicle in 120 degree heat up a 8% grade in the desert.

With 1990's technology.

I suppose you could have built better resolution on a lab pressure system. But the resolution we had was the required.

----
By design for the conditions I mean you need to know what the conditions are going to be.

SO the milligee laserstar

It needs to -
*Target while under milligees of acceleration.
*Fire while not accelerating
*Compensate for the moving parts in the cooling system
*Compensate for the moving of the laser mirror.
*Switch Targets at X rate.
*Hit a target that appears to be Y big at Z distance, using Optics designed to point the laser at a target Y big at Z distance.

It would probably be nice if it could also target and fire during some sort of extra manuevering or when the LaserStar is being hit by enemy fire, but those are not necessarily needed to do its main job.

Those are the conditions.

They arent
*parry some crazy Frank's axe

Or
*compensate for heavy recoil between each shot

You dont even need
*lead the target

Tony said...

All:

As a man once said, looks like I'm chopping and no chips are flying. I can take that. I really did read carefully and understand all of your arguments. I simply don't buy them, whether I think they are handwaving or just too optimistic. But I can't make you live inside my head and consider the things I've considered, in the way I've considered them.

Anonymous said...

Milo, fast flybys allow you to launch KKVs at maximum velocity relitive to your target. Also, who said that you can't launch more than one attack?

David; yes, assasins and spys would be more economical, unless the GRNB was afraid of the EU ploting on invading their territory.

Thucydides: reread the post; there are over 11 hundred individual KKVs targeted at each ship and they only have 100 seconds to kill or dodge all of them.

Does anybody else want to comment on my scenario?

Anita: thank-you for reminding us :)

Everyone else: I think that militay laser technology performance(for any period of time in the future you care to speculate on)will fall somewhere between that of the most and the least opimistic of assumptions. That still leaves a lot of room for discussion...

Ferrell

Milo said...

Jollyreaper:

"And I think that you do less violence to the story setting to just have parallel Earths and have the battle fought across them than trying to get spaceships and space polities to behave like terrestrial analogues with similar forms of warfare."

If you want your war to use WWII tech, then you can just set your story in WWII. Or set it in an alternate history version of WWII. No need for something weird like parallel realities. (I'd bet on us getting FTL before we get any way of visiting a typical fiction "just like our world with minor changes" parallel universe. Completely different universes that have been diverging for billions of years and never gave rise to humans, now those might actually happen.)

But many authors want something more. They want flashy technology that invokes our sense of awe in a way that decades-obsolete weapons won't (realism optional), or they want to explore the exoticness of nonhuman intelligences and our interactions with them (realism optional), or they even just want to have access to modern-day technological conveniences and social attitudes (realism optional). You can't get those from a setting only a few years before atomic bombs render superpower warfare on Earth impossible forever.

The next WWII (or vague analogue) will have to be set in space, because there's no way for it to be set on Earth.


"I like hard SF, semi-firm SF, squishy SF, mildly speculative fiction, wildly speculative fiction, and everything in between."

While I tend to appreciate hardness in science fiction, if a story is good enough I can forgive it a considerable amount of implausible science.

You want to write a romance between a human and a human-looking alien? Okay, it had better be a good romance.


"My only concern is that the story is internally consistent, coherent, has well-drawn characters whose motivations are either made plain or are murky by intent rather than poor writing and, most of all, the read is entertaining."

SECONDED!


"Like I've said before, my bias is towards a logical set of consequences stemming from the outlandish assumptions behind the setting."

That too.

Milo said...

Jollyreaper:

"Is magic real? Ok, how about necromancy?"

If necromancy exists, the very first question I'm going to ask is whether it's possible to raise the dead with their memories/personalities intact, without the spell requiring anything incredibly evil (bathing in the blood of virgins, etc.).

If this is possible, then everyone will want to be undead. Explore the social consequences on that. Three... two... one... go!


"Could wizards raise up something akin to a Haitian zombie, undead servants? If so, how does this impact the labor market? It would probably be even more disruptive than with living slaves."

How intelligent are the zombies?

If they're mindless, and need to be guided through any but the simplest tasks, then they will be more tools than laborers. They will cause little more upheaval than modern-day technological automatization - although having that technological automatization available at an earlier level of progress might have some ripple effects. (Incidentally, consider military applications. Far better to send expendable fodder that no-one will shed a tear over to do your fighting than to use living humans as cannon fodder, isn't it? But since zombies are stupid, they will need necromancers near the field to guide them. That adds a human angle to the story.)

If they're intelligent, then they're essentially just slaves. Maybe they're slaves with useful features like not needing food or sleep (but then again, they need to be continuously embalmed or they'll fall apart from rot), but overall most of the same tropes in any other slave-using scenario will present themselves. And sooner or later you're going to have warmbodies standing up for zombie rights while feeling very embarassed about the crimes of their ancestors.


"the understandable reluctance of the living to be turned into zombies."

Does zombification need to start with a living person? If all you need is a corpse, then it wouldn't be much different from how people donate organs today. I can see plenty of people being willing to donate their bodies to serve their country and their still-living children.

Milo said...

SA Phil:

"You dont even need
*lead the target"


Yes you do. Lightspeed lag.

But leading the target is probably going to be easy with modern/future computer technology - except that it means your sensors and weapons can't be pointed in the exact same direction, which poses problems for the "use your laser optics as telescope" idea.



Ferrell:

"Milo, fast flybys allow you to launch KKVs at maximum velocity relitive to your target."

"Approach as fast as you can and hit as hard as you can during your single window of opportunity" is a good deployment strategy for long-range missiles. Not for ships. And especially not for laser-armed ships.

These missiles might be launched from a planet, or they might be launched from the interceptor fleet when it's at its fastest point, before it begins its decelaration burn. But I'd design them like missiles (or multiple-warhead missile busses) - uncrewed, not designed to come back (so they can use their full delta-vee for the mission), and designed to put a lot of oomph into one blow rather than having any kind of staying power.


"Also, who said that you can't launch more than one attack?"

After you hurtle past, your milligee thrusters will take ages to reverse course. The enemy is likely to have coasted on and reached your homeplanet long before you can turn back for a second pass.

Even if you had the acceleration to swing back and forth several times at tens of km/s, that would burn propellant at an atrocious rate. And budgeting that much wasted delta-vee is going to leave you really, really slow compared to what you could do if you budgeted it more efficiently (i.e., not spending 80% of your time stepping on the gas pedal making accelerations you'll want to undo ten minutes later.).

Thucydides said...

While I am taking Tony's points under advisement, real world weapons laser demonstrators are performing under much harsher conditions than any spacecraft.

Consider, a C-130 has demonstrated a laser in ground attack mode, pointing and dwelling on a series of targets along a road. While the device was not weapons powered, it was on a heavily vibrating platform, moving through turbulent air. The US Navy recently set a small boat on fire from a range of 1.6 Km on the open ocean with both ships in motion. Various other weapons have been demonstrated on ground and air platforms targeting mortar rounds and ballistic missiles. These are demonstrators for next generation systems, not 100 years away.

As well, a functioning constellation would have multiple ships cooperatively targeting and sharing data. The weapons will have 3D target data (even without Hubble sized sensors) both to engage oncoming KKVs and to deliver their own attacks. This will start to break down in high "clutter" environments like LEO, and space warriors will be using all kinds of optical and electronic countermeasures to degrade target sensors as well.

So many factors will be in play in determining weapons effectiveness. We should also remember that things sometimes break out in your favour as well. US "Green Berets" fought a battle in Iraq where they engaged Iraqi tanks at over 3000m using Javelin ATGMs. Considering the published range is 2500m, this is pretty impressive. Even the rather ancient "Carl Gustave" and 60mm mortar used by Canadian soldiers had their effectiveness dramatically increased with new ammunition.

Thucydides said...

WRT Technozombies; it would be much simpler and more "realistic" if a natural or bioengineered virus disabled portions of the human brain to get the effect.

Similar ideas have been presented in movies like "Warning Sign" or 28 Days Later". There the McGuffin was the "Rage" virus spreading out of control. Of course, inducing "Rage" or "Zombie" virus in the colony life support system would be a much cheaper and quicker way of knocking off your opponent than space ICBMs or a demi operatic constellation of warships. I'd be a bit careful about salvaging anything after the war, though...

Milo said...

Oh, no zombie apocalypses please. There is simply no way any hi-tech military force is going to lose a battle with swarms of mindless bodies that attack in melee yet are too stupid to bypass even simple barriers like doors or stairs.

Think about it this way. If each human can reasnably count on killing even one zombie before being overrun, then we're going to kill more of them than they kill of us. Which means we're going to be killing zombies faster than new zombies can be made. No runaway apocalypse.

And zombies are pathetic enough - usually portrayed as expendable cannon fodder that rely on swarming to defeat prey - that even a civilian can expect to defeat at least one before being overrun. (Remember, a barricaded door is an effective fortification, and there are plenty of improvised weapons suitable for killing a slow-moving target with no ranged attacks.)

Actual competent militaries in a zombie war are probably going to lose more people to friendly fire or accidents than to enemy action.

Now if the zombie virus is airborne and can infect people from a distance, then it becomes a bigger threat, because you're still at risk even if you keep any zombies from coming near you. But at this point you essentially just have a normal super-plague apocalypse story, and the fact that the dead rise as zombies is a minor inconvenience that does little more than adding insult to injury.

jollyreaper said...


If this is possible, then everyone will want to be undead. Explore the social consequences on that. Three... two... one... go!


Great can of worms for a different story. I'm sure that this has been explored in the golden age of scifi -- if nobody dies, then people better stop having kids immediately. But there's a biological imperative to do so. So does the government prevent the masses from getting immortality drugs? Do we have a civilization-ending war? Is it kept a big secret? Are infertility treatments included with the immortality dose and you need a special license to have a child? There's going to be an average death rate due to misadventure, accident, suicide, and so forth. My guess is if society doesn't go batty and still has immortality, kids will be raised communally with everyone taking part, like having hundreds of extended aunts, uncles, and grandparents. Society would have a targeted population level and pregnancies would be targeted to raise kids in groups so they have peers, maybe a few hundred in a generation and maybe fifty years between generations. But this would assume that we have a nice, peacable way of keeping within the carrying capacity of the planet and don't just reproduce like vermin and suck up every available resource. Immortality would make the population boom of the 20th century look like small potatoes I think.

jollyreaper said...

How intelligent is the zombie?

Tailored to the purposes of the fantasy setting, the zombie is basically a robot. Zombies are docile and don't go searching for brains. They could be ordered to use as soldiers but would probably not be as efficient as real ones. I'm thinking that they could possibly perform very complex tasks but by rote from memories laid down when alive. Zombie cobblers, zombie bakers, zombie farmers. There can't be any possibility for rebellion or else there would be no good rationale to use them in place of living slaves.

In a society like I'm proposing, the drudge work and some manufacturing would be done by zombie labor. The more advanced stuff would be done by the living members of the society. Probably keep things on the same ratio as the romans or spartans historically speaking.

Now as for an added wrinkle, a couple of questions. Do these zombies rot after death? Classic zombies from the Romero setting don't have any biological processes going on inside. They eat but don't metabolize the flesh. They do terrible things to the conservation of energy. What powers them? We don't know. I like my magic to follow some kind of internal logic. So what powers them? Most black magic assumes that there's something powerful in death and sacrifice. I'd say there's a lot of power tied up in a human soul. Analogize that to cracking the atom. You crack a human soul, you're talking some serious mojo. Yes, you just killed that person for keeps and they don't get an afterlife but wow, what power! So maybe the zombie process is fueled by consuming the soul of the victim. Your friend gets zombified, it means you're not seeing him in the afterlife, you're not seeing him reincarnated, he's dead as disco, gone forever, never to return.

So I'd say the zombie's powered by the cracked soul of the victim, when the soul is emptied the zombie drops. Has access to the memories of the living person, is incapable of learning or thinking or feeling after zombification. Will obey orders, doesn't need food, has no biological processes. Probably include something about being toxic to any decay bacteria and some kind of treatment to tan the skin into human leather to keep it from breaking. Maybe semi-embalming egytpian-style to keep the innards from going all sloshy, take out the internal organs? Then there remains the question of what would physically be moving the limbs. Is it a kind of psychokinesis or what?

jollyreaper said...


Does zombification need to start with a living person? If all you need is a corpse, then it wouldn't be much different from how people donate organs today. I can see plenty of people being willing to donate their bodies to serve their country and their still-living children.


For the purposes of the story it would have to be done in a horrific kind of way in order for there to be the terrible conflict. If you can't take old people, if the zombie has to be made from a young and vigorous person in the prime of life, that means you're going to be killing unwilling victims rather than taking willing volunteers.

But it also raises some other interesting questions. So you start by zombifying your existing slaves. The cook slave makes your eggie-weggies just the way you like them. Now you've run through all the local slaves and can't seem to get any more and have to raid the next country over for fresh fodder. The new zombies can still cook but only in the style they're accustomed to. You can't train them to do any different. Ok, fine. Household slaves might be kept as living beings. But consider the field zombies. Your slaves knew how to cultivate your crops. Zombies from the next country over might grow the same crops. But you run through them and have to go two countries over and now you start running into zombies who are good at cultivating crops unlike the ones you're used to. Great, you've got zombies at home in a rice paddy but know nothing of wheat. Zombie armorers from your own country knew how to make steel weapons but two countries over and they only know how to work with bronze.


Plenty of good examples of the consequences of shortsighted actions. And for anyone who thinks "No country could possibly be so dumb," allow me to point to the US of A and our joy of outsourcing. What were you saying about no country being so stupid as to cut their own throats in the name of short-term profit?

I like the Greek idea of downfalls coming from people sewing the seeds of their own destruction. The failure of the zombie system would be inherent and inescapable.

Milo said...

Jollyreaper:

"But there's a biological imperative to do so."

A biological imperative to have sex or a biological imperative to have kids? With modern technology, they're not the same thing.

It's true that even given access to contraceptives, many people will choose to have children because they desire the emotional intimacy of raising a child. But I think people can get over that, or at least limit it to small enough amounts to be sustainable. (Remember that if you're immortal, there's no urgency to start your family now. You can wait and have some kids a couple centuries from now, when the Epsilon Eridanian colonies open, providing space for a massive new population base.) Or channel it into raising pets, but that's (A) less fulfilling than children and (B) people will probably want their pets to be immortal too.


"My guess is if society doesn't go batty and still has immortality, kids will be raised communally with everyone taking part, like having hundreds of extended aunts, uncles, and grandparents."

That's another good way to deal with it. If the birth rate is low enough that there's usually only one kid for every several dozen adults, then that one kid is going to be very precious to the entire community, and will likely receive attention from everyone. Which sates many people's parenting instincts without actually needing a lot of children.

Now answer the social implications of a spoiled brat being lavished attention by twenty adults...


"Society would have a targeted population level and pregnancies would be targeted to raise kids in groups so they have peers, maybe a few hundred in a generation and maybe fifty years between generations."

Hmm. What if people weren't that organized, though? What if the birth rate was naturally low, but people didn't specifically try to time/synchronize it?

Then children would grow up with no peers (but a lot of caregivers), so what would be the effect of that? ...Or at least few peers (we don't live in hunter-gatherer societies anymore, so even if there's only one child out of a thousand adults, that's still enough children in any major settlement to fill several schools). Which would actually completely eliminate the "problem", really.

Also if you did synchronize birthdays like you suggest, then that would reduce the "multiple caregivers" effect above, because right now your aunts and uncles are all busy with their own children. (If births are staggered, then your auntie's child will have reached adulthood by the time you're born, or vice versa, so both your parents and your aunt can give full attention to both children.)

jollyreaper said...


But many authors want something more. They want flashy technology that invokes our sense of awe in a way that decades-obsolete weapons won't (realism optional), or they want to explore the exoticness of nonhuman intelligences and our interactions with them (realism optional), or they even just want to have access to modern-day technological conveniences and social attitudes (realism optional). You can't get those from a setting only a few years before atomic bombs render superpower warfare on Earth impossible forever.

The next WWII (or vague analogue) will have to be set in space, because there's no way for it to be set on Earth.


All depends on the size of the handwave you're willing to accept. If you want to have non-human humanoid intelligences, I'd accept visiting a parallel Earth and meeting alternatively-evolved hominids sooner than I could accept the Na'vi. But this is a classic your milage may vary case.

There's only so far you could stretch the current WWII scenario plausibly on our own planet. If you want big carrier v. carrier battles, you've only got the Pacific war. The Japanese lost their carriers early on. It would be pretty hard to stretch the existing setting to give them more carriers, more battleships, and get big fleet v. fleet battles by the late war. You'd have to have everything go against the US in the early war, us willing to stop fighting hard and concentrate on Europe, things go badly there, and more things go impossibly right for the Japanese for them to build an even bigger fleet.

It just seems like less of a suspension of disbelief to say "Yeah, in this universe dimensional travel works with 1940's technology. Someone figured it out. Now here are the consequences."


While I tend to appreciate hardness in science fiction, if a story is good enough I can forgive it a considerable amount of implausible science.

You want to write a romance between a human and a human-looking alien? Okay, it had better be a good romance.


Yup. So much of the Firefly setting didn't make a lick of sense. What was my overall opinion? Oh, c'mon! It's awesome! Just run with it! But you have to be really, really smegging brilliant to get away with that. Turn out something like the Lost Fleet and there's naught to do but pick it apart for all the terrible failings.


"My only concern is that the story is internally consistent, coherent, has well-drawn characters whose motivations are either made plain or are murky by intent rather than poor writing and, most of all, the read is entertaining."

SECONDED!


Excellent! So I take it we have agreement on throwing eggs at the writers of Galactica? lol

Anonymous said...

(SA Phil)

I kind of liked the first two seasons of the new Galactica.

Got weird in a bad way later of course.

jollyreaper said...

Regarding the military effectiveness of zombies --

I'd say you'd need a sliding scale for the story you're trying to tell. The zombie survival guide talks about potential outbreak levels ranging from localized outbreak that can be contained all the way up to global pandemic.

In the Romero movies, any person who dies for whatever reason comes back. The only thing a zombie bite does is make sure you die in short order and then you come back as a zombie like everyone else. The whole collapse of society comes from panic and the sort of disruption you'd have if this was a repeat of the spanish flu going around and not walking plague.

The usual danger of zombies in these situations and the reason why they're so scary is because it's a tortoise and hair situation, only in this case the race is without end and the tortoise is undead. The rabbit can get miles ahead but then will have to eat and sleep. The tortoise keeps coming. The rabbit stays a mile ahead. The tortoise keeps coming. The rabbit has been running for days. The tortoise is hundreds of feet behind him. He can't risk resting now, the tortoise is coming near. But he can't keep going. And the tortoise is shambling along, never flagging.

As for technozombies, I LOVE trying to imagine the project meeting at the Umbrella company in the Resident Evil series. It would be hysterical to do as a Robot Chicken skit.

suit 1: So, we've got this idea for a military technology that will revolutionize everything! The T-virus. We're making zombies.

boss: I'm not sure I follow you on this one.

suit 2: We can create a virus that will turn people into flesh-craving zombies.

boss: Yes, I understood that part. But how exactly are you planning on commercializing this? It's not like we can put this on television and say 'Buy our product, you'll become a zombie.'

suit 1: Military applications, as I said.

boss: What, you're going to try and sell the Pentagon on the idea of turning American boys and girls into zombies?

suit 2: No. They use the virus on the enemy.

boss: Enemies who presumably could be bought off and bribed not to fight our soldiers. And you want to turn them into cannibal killers who cannot be reasoned with and will turn everyone else in the country into cannibal killers.

suit 1: I don't think you comprehend the full potential of what we're talking about here.

boss: Please, enlighten me.

suit 2: It'll be awesome!

Suit 1: It's a multi-step process. Step 1, make zombie virus. Step 2, ??? Step 3, profit!

boss: Why do I feel like I'm in an episode of Better Off Ted?

jollyreaper said...


Now if the zombie virus is airborne and can infect people from a distance, then it becomes a bigger threat, because you're still at risk even if you keep any zombies from coming near you. But at this point you essentially just have a normal super-plague apocalypse story, and the fact that the dead rise as zombies is a minor inconvenience that does little more than adding insult to injury.


In general, any zombie plague would ultimately degenerate into standard post-apocalypse stuff once the first big batch dies off. Zombies shouldn't be able to exist forever. Even Romero/Brooks zombies are supposed to fall apart after a decade. The potential for recently-deceased humans to zombifiy would still remain. Just consider what that would imply for sleeping arrangements. Husbands and wives wouldn't even be in the same bedroom anymore. What happens if your spouse dies while you sleep? You wake up with a zombie munching on you. Everyone sleeps in separate rooms, doors locked and barred. Paramedics responding to accidents will always be armed so they can shoot patients through the head if they die on the scene lest they rise again. Zombies not powerful enough to cause a total apocalypse would still be a big enough threat to render society alien to us.

And just as a personal quibble, I hate the whole virus angle. Romero zombies set in the real world work best when they're unexplained and their sheer impossibility are part of the horror. None of this should be happening, none of this should be possible, that it is breaks your brain and any expectations of what should be. The moment someone calls it a virus and starts trying to explain how it works everything falls apart since there's no bloody goddamn way it could possible happen this way. You might, MIGHT be able to run with a rage virus scenario if you work really hard but these people are not going to go from infected to ravening in five seconds. And this also means you'll go from zombie story to standard post-apocalypse, as you mentioned, in the few weeks it takes for the rage zombies to starve to death, being living rabid people and all.

Personally, I'd like to see more stories set in a "civilization surviving decades into the zombie era" setting simply because total collapse in the face of a zombie apocalypse has been done enough. Something different is always welcome.

jollyreaper said...


A biological imperative to have sex or a biological imperative to have kids? With modern technology, they're not the same thing.


Many women are baby-mad. Men can catch the fever, too. It's not always just an "oops" result of having sex.

That's a good point about people not feeling the psychological urge of the biological clock if they think they can plan on having their babies when they want them. We've seen the changes between third world and industrial societies where the greater the level of advancement, the lower the birthrate. That's probably a combination of factors such as greater chance of each child reaching adulthood, huge investment of capital in child-rearing in industrial societies, pressures from school and careers making family planning a necessity, the ability to even talk about family planning, etc.

As to the approach for raising kids -- how to plan the births, trying to have peers, not planning births, etc, that could end up representing customs and laws from one polity to another. And the requirement for new living space could well drive the urge for going out into space. Christians following the Full Quiver doctrine are supposed to pump out as many kids as possible and that's just not viable on Earth. I'm not sure what the potential carrying capacity of the whole solar system would be but I'm sure it's pretty astounding. Just how many Island III's could be constructed from the asteroid belt?

Actually, now that I think of it, an immortal human society like this with a low birth rate would end up being rather much like the Tolkein elves. Hopefully with a little less singing. :)

Rick said...

I prefer the dead to stay politely in their graves, thank you very much, and not rudely show up at the feast. So I'll stay away from the whole zombie discussion. :-)


This will start to break down in high "clutter" environments like LEO

As a general note, my arguments for long combat ranges (multiple thousands of km) generally break down in cluttered space like LEO. If that is where the fighting happens, laserstars won't be invited to the party, or will be there awkwardly in a secondary and unintended role.

Milo said...

Re: Infectious apocalypse zombies. (Not to be confused with necromancer slave zombies.)



Jollyreaper:

"The tortoise keeps coming."

Until you kill it.

Dead tortoises, to my knowledge, do not win many races.

I am not going to run from a zombie. I might retreat to a stronghold, but any movement is going to have a definite destination in mind, not just "keep running, out in the open, until I drop from exhaustion". Once I'm holding a position of strength, I strike back.

And humans have the advantage of being able to reproduce without the assistance of zombies. So in a long-term attrition scale, humans are going to be the ones who keep coming.


"What happens if your spouse dies while you sleep? You wake up with a zombie munching on you."

You know, many people consider it romantic for a husband and wife to die together in their sleep. This probably isn't what they're thinking of, though.


"Everyone sleeps in separate rooms, doors locked and barred."

Actually, just barring will do. You'd use "locks" that zombies are too stupid to open, but that any living human can easily handle from either side of the door, without having to fumble for a key. Makes it much more convenient to work regular barricading into your daily routine, and keeps locked doors from being a constant obstacle for emergency workers.

Knowing people, though, they're likely to get lax in their precautions if no-one in the family is currently showing signs of failing health.


"Personally, I'd like to see more stories set in a "civilization surviving decades into the zombie era" setting simply because total collapse in the face of a zombie apocalypse has been done enough."

If you have "anyone who dies for any reason becomes a zombie" type zombies, then yeah, you could get some of the effects you'd mentioned. You'd still have those effects, though, even if you wiped out every single currently existing zombie on the planet (which you probably would, since zombies are wimps). So you can't exactly say that the zombies themselves are responsible for the mess.

You'd get a mighty unpleasant situation, but quite different from a typical zombie apocalypse. The actual problem is that the meaning of "death" just changed for some reason.

jollyreaper said...

I love Sarah Jane. A glimpse of a survivable zombie apocalypse in Australia.

http://www.youtube.com/watch?v=gYxs7Y7ulrM&feature=youtube_gdata_player

Milo said...

Rick:

"As a general note, my arguments for long combat ranges (multiple thousands of km) generally break down in cluttered space like LEO."

I'm convinced planetary orbits are going to be a significant tactical environment, but that doesn't necessarily mean low orbits. I still like the idea of fighting for control of high orbits before moving into low orbit, though I'm not sure how well it stands up to scrutiny.

Low orbit is close enough to the surface that any kind of surface-to-orbit defenses are going to be a dominant factor here. Thus, low orbit combat cannot be considered in isolation from what's happening down on the planet, except for the exceptional case of two imperialistic powers fighting for possession of a small colony to weak to defend itself against either.



Jollyreaper:

Oh, and another thing I almost forgot about the immortality thing.

I started this line of discussion when we were talking about necromancy, and so suggested that the form of immortality in this case would be as sentient undead.

But being undead is probably going to hamper your ability to have children. Oops.

So now while people can live forever as pretty dressed-up corpses, they can still only have children in the first few decades of their lives. Oops.


But, let's take a more positive tack. Since elves were mentioned, let's just ditch the technology or magic thing and suppose a species that is just naturally immortal, and was so since the dawn of their civilization.

Okay, so now you have people from the dawn of your civilization still walking around. Hmm.

How does that work, if you don't ruin your elves by having "medieval stasis"?

Now, we know that old people can and do learn and adapt to technologies invented after they were born. But just how would society look, if one of the scientists working on cutting-edge technology today still remembers that day, several thousand years ago, when he personally forged the world's first bronze tool? Technology, social mores, religion, fashion and art, and so on change, but the same people stay and observe throughout. (Well, some of them - some ancients would still be dying, and there would be a fair number of younsters around, but there would still be a very significant number of people who can still tease each other about "Remember back when you bet me five sheep that these 'cities' things would never catch on?", preferably in front of the younger generation. On a webforum.)

But there is always the quirk that in order to keep the elves actually having a long lifespan, you have to keep them from constantly going to war. That's going to cut their life expectancy down, no matter how long they can theoretically last if not killed. Is there a logical way to get from "low birth rate, low natural death rate" to "more peaceful"?

Anonymous said...

Sorry Milo, I didn't make myself clear, my fault; what I was refering to when I said you could make more than one attack was not in referance to one constellation attacking, turning around and attacking again, but of launching several intercepting attacks staggered by hours or days apart to attrit the incoming ships, until they are (hopefully) too weak to be successful against the orbital forces. And, while I would use a mix of manned and unmanned ships to attack, you are perfectly free to use whatever you feel is the best method of attack.

Again, sorry for the missunderstanding.

Ferrell

Milo said...

Ferrell:

"Sorry Milo, I didn't make myself clear, my fault; what I was refering to when I said you could make more than one attack was not in referance to one constellation attacking, turning around and attacking again, but of launching several intercepting attacks staggered by hours or days apart to attrit the incoming ships, until they are (hopefully) too weak to be successful against the orbital forces."

Multiple waves is probably less efficient than sending everything at once (Lanchester's law), unless you have some sort of strategy to justify it (I don't see one).

Anyway, I really don't think major stuff like capital ships can be deployed so casually that you can just say "oh, that wave has overshot the enemy, launch another one". That kind of cavalier attitude to numbers does, however, make sense with expendable missiles.

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