Monday, March 28, 2011

Space Warfare XIII: The Human Factor

Discussion of the recent post on Interstellar Empire led to a question that until now failed to get a post of its own: the role, in space warfare, of drones versus ships carrying human crews. Consider this deficiency now corrected.

A few provisos apply. Set aside for now the question of whether warfare, as we have known it and too much loved it since the Iliad, may be obsolescent as a viable mode of conflict among post-industrial communities.

Also set aside the Plausible Midfuture, a place where warfare in deep space is doubtful even if Earth orbital space is armed to the teeth. Set aside as well the general messiness of warfare on planets; my concern here is with space combat. We are dealing here with space armadas, a concept that is demi-operatic at least.

Will these armadas be made up primarily of warships with human crews - the familiar classical vision - or largely of robotic craft?

A lot of this comes down, I would argue, to good old money. The first 50 years of deep space exploration have been exclusively robotic because robotic spacecraft are cheaper. They are cheaper for several reasons: They can be much smaller; except for sample returns they don't need to come back; and in fact they don't even need to always get there.

So far as I can recall, every mission to the outer planets has (so far) been a success, but we only reached the point of batting .500 against Mars since I launched this blog. Such a loss rate was regarded as acceptable for human missions in the 16th century, but not in the 21st. (The more so because the enormous cost of human spaceflight, and resulting high profile, makes human spaceflight losses more controversial than, say, helicopter crashes.)

The situation in warfare is somewhat different, because soldiers are in some fundamental sense expendable - many of our military traditions are, in one way or another, built around that fact. But they are not lightly expended, if only because high quality crews are costly to train and difficult to replace. For post-industrial societies, where untimely death is no longer a sad commonplace, public resistance to casualties may be problematic even for authoritarian regimes.

Cost and risk of losses, taken together, are ample reason for the designers of combatant spacecraft to automate them so far as is practical. But how far is practical?

Kinetic weapons will have no human crews, for obvious reasons. There are almost equally strong reasons not to put crews aboard the buses that deliver them. Kinetics are most effective in a single wave that saturates defenses - the faster they are thrown the harder they will hit, and the less time the defense will have to stop them. This argues for a bus that uses its full delta v for maximum closing rate, rather than holding back propellant in order to recover the bus. For its basic mission it need not be very sophisticated, and you will not be re-using it anyway, at least not anytime soon.

So it is probably cheaper to make the bus expendable.

Lasers are a different matter, as are alternatives such as particle beams. (And for that matter kinetics, if these are slung on their way by coilguns. Flip side, bomb-pumped lasers are expendables, with military properties similar to kinetics.) A laser star is inherently reusable, and suited to missions, such as blockade or maintaining a 'presence,' in which repeated engagements may be required. A laser and its associated optics are also presumably sophisticated equipment. On all of these grounds putting a crew aboard a laser star seems much more plausible than putting one aboard a kinetic bus.

But what exactly would the crew be called upon to do? No gunners' mates are needed to shove photons into the breech, or even aim the laser. Actual precision aiming of the beam will be automated in any case, and assigning targets can be done from a few light seconds away.

The other traditional role of ships' crews is maintenance and repair. But drive engines and megawatt lasers do not, so far as I can see, provide much scope for onboard servicing, let alone damage control during battle. Repairs of either one pretty much need the services of a cageworks. Occasional replacement of smaller failed systems, or whacking balky parts with a wrench, can be done by service teams based elsewhere - at a space station, for defensive orbital forces, or aboard a tender for deep space constellations.

It is a peculiar fact that both many space emergencies - such as onboard fires or air leaks - and much of the corresponding scope for human emergency repair, relate specifically to life support habs. (Propellant tanks can also leak, but offer precious little chance of onboard repair.) I suspect, indeed, that life support maintenance will be a major role of space crews. But this sets up an odd circularity. Take away the hab and you eliminate many of the emergencies that a crew could respond to.

The final role for humans in space combat is command and control, especially rules of engagement decisions. We might not want to trust even high level AIs with these decisions - either because we are not quite sure of their motives, or because they have no motives at all, and so can free us of everything but the need to decide. But the scale and probable tempo of space combat are such that - as mentioned above concerning target designation - these functions generally don't need to be aboard the weapon platforms. Why not offload them to the 'tender' that provides teams for the occasional maintenance call?

Back in Part III of this series I gave the following description of a space combat constellation:

Taken as a whole you might call it a fleet. But it more nearly resembles a mobile, distributed, and networked fortification, deploying in action into a three-dimensional array of weapon emplacements, observation posts, and patrol details, all backed up by a command and logistics center.
But even supposing that a main battle force is built along these lines, what about smaller independent mission packages - the equivalent of a cruiser, for example, for patrol missions?

Contrary to the (understandable!) assertion of a well known Evil Website, space is not an ocean. At sea, a single 10,000 ton ship has major advantages over four 2500 ton ships. It is more seaworthy, far more comfortable for its crew, harder to sink, provides a higher and dryer command for guns and sensors, and can maintain higher speed with less power and fuel consumption.

In space these considerations apply with far less force, if they apply at all. A single large hab pod is likely preferable to several smaller ones - but only the command ship / tender needs a hab pod at all. And the other force elements can be carried as riders, if desired, separating only to deploy for combat.

If your propulsion tech involves an electric drive powered by an external reactor, which also supplies the primary laser, you want to match the drive, reactor, and laser, which does argue for putting them together aboard the same spacecraft. And you might reasonably be less than comfortable about separating the crew hab from the main drive. But if your setting has fusion drive, or any self-contained drive, this is much less a consideration.

One other human-factor consideration to keep in mind was brought up in the linked discussion by commenter Tony: What happens to the morality of warfare - such as it is - when no soldiers put themselves at risk to fight it, because the fighting is all done by robots?

In the scenario I have outlined above this is not really the case. The constellation has a human crew, aboard the command ship / tender, even if it is 'behind the lines' relative to the weapon platforms. If the combat units of its constellation are defeated the crew must retreat, surrender, or face destruction - the choices that have always faced combatants who were disarmed in battle rather than killed outright.


Related Links:

Atomic Rockets, of course - especially, but not exclusively, the pages on space warfare.

And previously in the Space Warfare series on this blog:

I: The Gravity Well
II: Stealth Reconsidered
III: 'Warships' in Space
IV: Mobility
V: Laser Weapons
VI: Kinetics, Part 1
VII: Kinetics, Part 2 - The Killer Bus
VIII: Orbital Combat
IX: Could Everything We Know Be Wrong?
X: Moving Targets
XI: La Zona Fronteriza
XII: Surface Warfare

Also ...

Battle of the Spherical War Cows: Purple v Green
Further Battles of the Spherical War Cows


Space Fighters, Not
Space Fighters, Reconsidered?

And, indulging in heresy -

Give Peace a Chance

The image shows Achilles fighting Hector.

Thursday, March 17, 2011

De Gustibus Non Est Disputandum

Meta raised its head again, in a big way, in discussion of the last couple of posts on FTL. This should not be a surprise, because the rather problematic physics of FTL brings us very close to the boundary line between science fiction and science fantasy. (Including the question of whether it is valid to distinguish them at all.)

The perspective of this blog from its beginning has been that SF is a subgenre of Romance, a term now narrowed down by marketers to a different subgenre of itself. Romance in all its subgenres is distinct from 'realistic' fiction, which is largely why academic literary criticism has been rather nonplussed by it. Realism, in this context, is mostly about psychological realism in characterization, not Realism [TM] in technology, physics, or other aspects of the setting.

Yet that latter kind of Realism [TM] is itself a very relative thing, and arguably amounts largely to a stylistic flourish. Take for example the question of space warfare, a subject that probably drew many of you to this blog.

There is, to be blunt, precious little 'realistic' about clashes of armadas in deep space. Half a century of space travel combined with enormous military budgets has shown mainly that the world's major militaries have zero interest in space armadas. The US never deployed any manned space warcraft, unless you count 'Blue Shuttle' (which the USAF never wanted). The Soviet-era Russians dabbled a bit, but soon lost interest.

For that matter, from a genuinely realistic perspective there is not much basis for any of the familiar space tropes that we know and mostly love here. The exploration and exploitation of space, as of the ocean floor, is much better suited to robotic or remote-controlled vehicles and systems. Deep space does add the complication of light lag: Teleoperators at JPL in Pasadena can't guide machines on Mars in real time. But this is only a limited constraint, and - let's be honest - there are cheaper and more convenient workarounds than sending hundred-ton human habs to Mars, at enormous cost, plus the even more enormous cost of bringing them and their crews back safely.

Any number of unforeseen circumstances might change all this, and provide some McGuffinite that justifies extensive human space travel. We have discussed such possibilities before on this blog, and you can safely guess that we will discuss them again.

Stories about space travel, on the other hand, require no such hypothetical McGuffinite. It is sufficient that space travel is Cool. But even fictional space travel is subject to the willing suspension of disbelief.

How disbelief gets suspended, and in what ways, is in fact arbitrary and genre-dependent. Practically all fiction, including realistic fiction in the conventional sense, expects us to take its characters as people, not figments of the author's imagination. Even traditional literary criticism joins in this pretense, talking about Achilles or Elizabeth Bennet as if they were actual people. Experimental fiction that overtly admits to being fictional is arguably 'metafiction,' while time-honored framing devices for fantastic fiction, such as the old lost manuscript, have long fallen out of active use, and would be evoked today only for retro flavor.

I have an aesthetic bias in favor of the trappings of Realism [TM], both in the technical details of spaceships and the social details of why someone is paying to have them built, which is why Rocketpunk Manifesto belabors all of those questions about why people might actually go into space in large numbers.

It is important to emphasize that this is precisely an aesthetic bias, and my biases can be amazingly idiosyncratic and narrow. For example, spaceships that look like the Navajo missile of the 1950s are both coolific and Realistic [TM] in my eye, while spaceships that look like a V-2 with wings look corny, dated, and implausible. Never mind that they are both equally genuine design concepts, little more than a decade apart and both more than half a century old - or even that one evolved directly from the other. One looks right to me, while the other doesn't.

Many of my SF biases are reflected by the Tough Guide to the Known Galaxy, from my old static website. Even though it is largely a snark at convention space-fiction tropes, fundamentally that is still how my tastes run. I neither apologize for those tastes nor defend them. These tropes are a perfectly legitimate branch of SF as it has developed over the past century or so, but by no means the only perfectly legitimate branch.

From one perspective, science fiction itself is obsolete - a creation of the industrial revolution, an inherently transitional phase when visions the pre-industrial world could scarcely have imagined became possible to think about, even if some may never be possible to achieve. It is really, really hard today to come up with SF ideas that have never been written before.

On the other hand, SF has permanently expanded the frontiers of Romance - including the revitalization of its bookstore neighbor and rival, fantasy, along with a host of spinoff subgenres. None of it is realistic, but much of it thrives on the artful faking of realism.


The launch images of the SM-64 Navajo come from an aerospace history blog. Compare to the ramjet shuttle at the lower right of the RM logo image above.

Wednesday, March 9, 2011

FTL Part II: Just Plain Cheating

In our last exciting episode we considered the possibility that the dictum Causality, Relativity, FTL travel: chose any two may not be strictly true. Consult the comment thread for discussion, particularly some thought experiments offered by commenter Luke.

I cannot vouch for the validity of these arguments, only that they are either a) valid, or b) extremely high quality bullshit, and I choose a as my working hypothesis.

Einsteinian street-legal FTL is, as the discussion takes note, subject to certain constraints. Its use in a story is, in turn, subject to some meta-level contraints. So far as I can tell, it is consistent only with the 'jump' style of FTL, in which you pre-select your destination before hitting the big red button. FTL in which you navigate freely seems ruled out. And you are taking your chances with drawing (or narratively describing) a 'subway map' of FTL jump routes, unless you can ensure that your map meets the requirements for a directed acyclic graph.

You have been warned.

Having said that, the whole subject is pretty much moot unless you are a physicist, or can credibly impersonate one. Nearly all your readers will ignore your validation, and assume either that you are jiving them as part of the story, or else that you are simply a crank. (Which will not help them buy into the story.) Within the SF world, FTL is more or less universally understood to be a pure dodge, dumping physics for the sake of story. And it is just as universally accepted on that basis.

A point made in comments to last post was that there are also STL workarounds, even for such tropes as interstellar empires. Said commenter Horselover Fat: "For FTL, you need to dump Einstein. For STL empires, you need to dump your cultural assumptions. And you choose to dump Einstein?"

Very good question. My answer would be that cultural assumptions tie in closely to characterization, right at the heart of fiction. Change them greatly and your story pretty much has to be about those changes. Dumping Einstein, not so much. (Note: I am not saying that you need to ignore the laws of physics, only that - in space opera - you can.)

You do still have to fake it convincingly. As I suggested last post, the less you say about your specific handwaves the better off you will probably be. You also have to adhere to some internal consistency. If FTL jumps require generating Stupendous Energy on demand, you need to deal with the implications of a technology that can do this. Similarly, if you need to travel 100 AU in normal space to reach jump points, you need a normal-space drive capable of doing so in convenient time. (And if you stick with relativistic STL, you need a beaucoup powerful drive.)

All of which produces, or can produce, its own awkward complications. If your interstellar tramp freighter has a drive engine capable of slagging a continent, the movement of such ships anywhere near an inhabited planet will be very strictly regulated. This may spoil some otherwise charming tropes. (Think Firefly.)

There are a host of other possible complications to bear in mind. If FTL jumps can be made by small spacecraft just above planetary atmospheres, you've opened the door to bomber-mission nuclear strikes, or even interstellar ICBM strikes. But if it takes too long to reach jump points in normal space you could end up at least partly defeating the purpose of FTL.

Another criticism I have seen is mildly meta: settings in which there is FTL for convenient star travel, while the rest of the technology pretty much resembles the Plausible Midfuture [TM]. The problem here is that you have supposedly had a fundamental revolution in physics, yet with no technological consequence other than FTL itself. How remarkably convenient ....

A reasonable counter-argument might be that relativity itself gave us the atomic bomb and nuclear subs to deliver it, but no atomic motorcycles or force-field steak knives. Nuclear power plants put out the same kind of juice as coal-fired plants, and for most story purposes are pretty much invisible. I imagine that modern physics is implicated in a host of everyday gadgets, but not in dramatic ways.

So, the presumed future physics that gives us FTL might also give us antigravity drive and other Cool Stuff, or - for different desired values of coolness - might have few other obvious effects besides fast interstellar travel.

For that matter, a Pretty Strong argument could be made that all of this is tech geek navel gazing, irrelevant to the practical problems of SF world building. Heinlein's Starman Jones remains a favorite of mine in spite of an FTL that requires you to violate relativity in normal space, before you even get to make the FTL jump.

And to take a more modern example, I thoroughly enjoyed Elizabeth Moon's Heris Serrano books, though the stuff that reads like hard SF is really almost pure bluff. The fact of the matter is that if onboard instruments indicate the approach of an enemy ship, and the characters respond to this situation in a persuasive way, we as readers do not insist that they stop to calibrate their instruments for us.

On the other hand, this blog is more or less dedicated to the art of faking details convincingly.

Discuss. (As if you needed an invitation.)

The subway-esque hyperspace image comes, via Google Images, from a screensaver website.

Thursday, March 3, 2011

FTL Part I: An Honest Cheat?

It might seem contrary to discuss FTL only after a post on interstellar empire, a concept that pretty much depends on star travel being cheap, convenient, and above all fast. (Yes, there are STL scenarios, but they are so stretchy that violating General Relativity suspends less disbelief.)

But in broader perspective it is our desire for interstellar empire, or other such cool settings, that calls out for the willing suspension of disbelief in the first place. All spaceships, as a commenter on this blog once observed, travel at the speed of plot, but that is especially true when it comes to FTL. Spaceships in the Plausible Midfuture have some of the constraints of real-world vehicles, and plots must work around them, but the only constraint on FTL is that it must sound convincing to readers who want to be convinced, at least while reading the story. (Although FTL systems in SF not infrequently fail even at that.)

Unlike last post, this time I remembered to link the relevant page at Atomic Rockets, which covers or links the relevant physics and pseudo-physics, and offers some useful FTL typologies. Also a link to my observation in the Tough Guide to the Known Galaxy that all FTL tech is equivalent to flipping tarot cards while chanting in Welsh - i.e., effectively it is magic.

And a post here from last year which noted that contemporary physics has just barely left the door open to FTL, subject to certain constraints. The relevant effect of these constraints - as I understand it (and General Relativity is not my field of expertise) - is that you can stay out of temporal trouble so long as your baseline FTL routes do not cross-connect.

To follow the rapid transit metaphor I used in that post, you can have multiple routes out from Earth (via wormholes or whatever), with as many branches and sub-branches as you want, and travel times can be as fast as you want them to be. But each station can only be on one line. If you can take two separate routings to reach a given destination, of differing length, then you have to pay the temporal piper.

For example, from Sol to Sirius is 8.6 light years, while from Sol to Wolf 359 is 9.0 light years. Given tramlines equipped with a suitable array of oscillating hands, you can reach either one in in a month by your onboard clock, or an hour, and return in similar time. In Earth's frame of reference, going outbound you are in fact travelling nearly a decade into the future, and returning you are going nearly a decade into the past. This produces no awkward time-travel-esque results, because you don't return to Earth before you left, and you can't get back to Sirius for a second visit prior to your first one.

From Wolf 359 to Sirius is 7.7 light years, so the roundabout route to Sirius via Wolf 359 is 16.7 light years. If you could simply open another tramline, you could travel to Sirius via the indirect route, arrive there 17 years from now, read some stock quotes, return by the same roundabout route to Earth, then go by the direct route, and invest in Sirian stocks years earlier. Big trouble, and not just for stock markets.

So, to avoid breaking causality, such routings must be ruled out, or at least force you to twiddle thumbs those extra eight years instead of raking in a bundle. I don't begin to understand the required coefficient of jive, but apparently it can be done without violating General Relativity, at the price of making such roundabout routings very inconvenient.

(Commenters who do understand this stuff are welcome - indeed, invited - to step in and expand on / correct these points.)

The hitch is that for story purposes we probably want those roundabout routings - not to travel into the past, but merely to run blockades and the like.

My impression is that there is still a workaround. Simply assume that all FTL travel to Sirius proceeds via Wolf 359, but that there are separate 'local' and 'express' tramlines along the route - the former stopping off at Wolf 359, while the latter passes right through without entering normal space.

If each entry or exit from a tramline involves a cost (e.g., reaching the jump point through normal space), then regular Sol-Sirius travel would follow the express tramline, passing by Wolf 359 nonstop. But the local routing, stopping off in normal space at Wolf 359, would remain available when needed for story purposes.

Yes, this is more than a little strained (and possibly downright wrong), but hey, we're talking about FTL. The alternative, so far as I can see, is simply blowing off a lot of well-establish physics entirely. Remember, it isn't as if Einstein kicked Newton onto the ash heap; old Sir Isaac still gives an approximation good enough for interplanetary travel planning.

Moreover, the above gimmickry can be almost entirely buried out of sight, at least so long as your intended flavor of FTL is jump-oriented, and you don't get deeply into the weeds about the sequence in which routes were established in the first place.

Having said that, this approach should probably be left to physicists, or people who do General Relativity as a hobby, and might as well be physicists.

My more general advice on FTL - which I seem to have arrived at via Wolf 359 - is to say as little about the mechanism as possible. Don't talk about wormholes, don't talk about Alcubierre, or any other present-day speculation. All you will do is date yourself, because I don't need to travel into the future to guess that these particular edge-of-the-envelope speculations will be superceded.

Bury all that theoretical stuff under a couple of toss-off jargon terms - Horst-Milne congruencies, Alderson Drive, whatever - and concentrate on what actually matters, which is how FTL actually operates in a setting: size and cost of the gizmo, apparent travel times, available routings, and so forth.

Some of which I will (probably) discuss next post.

Related links: Atomic Rockets, Chanting in Welsh, and Rapid Transit.

The image comes from a Battlestar Galactica website.