Tuesday, June 7, 2011

Sluggish Pickup, But the Mileage is Spectacular


This used-car dealership on mid Market St. has intrigued and amused me since moving to Babylon by the Bay.

Since ordinary batteries involve ions, I suppose the Chevy Volt or even a Prius could be said to use a form of ion propulsion, but how many people associate electric cars with 'ions'? In any case there is no indication that this place specializes in electric cars. Their website does not explain the name, but I can only guess that the name is intended to evoke ion propulsion for spacecraft.

The logo - for a business that touts itself as the bay area's 'newest car dealership' - sort of goes along with that connotation, I think. Doesn't it have a bit of Zeerust retro flavor?

Ion drive, in fact, is probably the only high specific impulse that qualifies as a trope, in the (correct) sense used by the Evil Website. A broad cross-section of people, not just geeks, have at least some vague sense that ion drive is an advanced and futuristic space drive, yet at the same time a 'real' one, not pure sci-fi jive. Perhaps its status was confirmed by Trek, either The Wrath of Khan or its TOS progenitor episode, in which ion drive was characterized as an archaic technology.

Nuclear-thermal propulsion, AKA atomic rockets, do not quite qualify as a high specific impulse drive, its classic form outperforming chemfuel by a modest factor of two or three. Fusion drive, much debated and belated at websites like this one, does not seem to me to have quite made the jump from geekdom to the broader public. The same applies to generic torch drive. Possibly Avatar will promote antimatter drive to trope status; only time will tell.

Compared to these latecomers, ion propulsion has an enormous headstart. Somewhat remarkably, Robert Goddard considered ion propulsion more than a century ago, in 1906. Konstantin Tsiolkovsky published on the subject in 1911 while Goddard performed actual laboratory experiments in 1916-17.

The rocketpunk-era books I read as a kid about Our Future in Space almost always mentioned ion drive, generally in the context of what I now call the plausible midfuture. I recall one book with great illustrations that portrayed an ion drive ship under the heading To the Stars. The next page had a photon-drive ship, To the Galaxies. The temporal implications of intergalactic STL travel were left undiscussed.

I don't have any specific recollection of ion propulsion in rocketpunk-era SF. Heinlein had no interest in space drives that lacked bone-jarring acceleration; his propulsion sequence thus went from nuke thermal to Ortega's mass-conversion torch to the unabashedly magitech Horst-Milne-Conrad impellor.

Clarke also never specifically mentioned ion drive, at least that I recall. He was usually rather cagey about deep space propulsion details, though I often got the impression that some sort of electric drive was implied.

Therein, of course, lies the rub. As I understand it, ion thrusters are in fact not suitable for deep space propulsion of large, human-carrying spacecraft. Their thrust is very low, even by high-ISP standards, and apparently the thrusters cannot readily be scaled up. Ion propulsion is now in service, used by the Dawn probe among others, but there are unlikely ever to be ion-drive ships.

But in trope terms - in the mind of the popular culture - ion drive is synonymous with electric space propulsion in general. Technologies such as VASIMR, while they do involve ionized plasmas, are not 'ion drive' in the strictly technical sense. But in some broader cultural sense they are indeed ion drives, technical details be damned. If it emits a faint blue or purple glow, produces gentle but steady thrust for days, weeks, months on end, it fits the cultural vision of ion drive.

Though I wouldn't recommend it for Bay Area freeways.




The image was taken from my el cheapo ('free') smartphone while riding a vehicle with electric drive: the F Market streetcar.

184 comments:

Bryan said...

I think ion drives get ignored by SciFi for the very reason that they make for boring reading/TV. Your average jane/joe isn't going to want to read/watch a long description of a slow acceleration. Seriously, how exciting would be tie-fighter battles in star wars have been if the ships were limited to 0.000001G acceleration?

In terms of scalability, I was under the impression that they could be "scaled" by using arrays of multiple smaller drives. Many depictions of larger ion drives that I have seen usually appear as honey-comb like structures; presumably reprenting such arrays.

Tony said...

The future of ion propulsion is probably with the Hall effect thruster, not with the gridded thrusters NASA has used up to this point. NASA has a serious NIH problem with Hall thrusters, at least partially because the Soviets beat them to thep unch on developing and launching fully qualified flight articles. But the USAF and commercial operators love Halls for station keeping and orbital maneuvering. A Hall thruster in a solar-electric configuration was used to propel the ESA SMART-1 lunar probe from Earth to Lunar orbit. It logged hundreds of on-off cycles over 17 months, with on cycles lasting from several hours to several days.

Hall thrusters, due to their annular configuration, can also be nested. Two thruster channels, one nested inside another could, for example, provide three different power levels from a single thruster assembly. Three nested thrusters could provide seven different power levels. Numerous thruster assemblies run in parallel could deliver potentially hundreds of different power levels.

Of course, the limiting factor is not scalability by addition. That's a relatively straightforward exercise in electrical engineering and plumbing. The real problem is providing enough electrical power in a light enough package. That's going to hang up every electrical rocket technology, whether it be relatively simple ion motors to VASIMR (or whatever else comes along).

Anonymous said...

=Milo=



Bryan:

"Seriously, how exciting would be tie-fighter battles in star wars have been if the ships were limited to 0.000001G acceleration?"

People like sailing ships, don't they?

A realistic ion thruster is a ship engine, not a fighter engine. It's what you use to get from point A to point B.

Incidentally, there's at least one (really old) computer game about land-based tanks which featured an "ion drive" as one of the components you could install...

Anonymous said...

I think that the main problem with scalability of ion engines is in that they are limited to a certain amount of charged particles flowing through the engine because of charge repulsion. You can only shove so many ions out through the tube at one time. Other than that, yeah power and plumbing are right up there.

The use of ion drives on unmanned craft should increase, but as far as manned vehicles go, not so much.

Ferrell

Bruce Lewis said...

The world is not waiting for a good high-thrust ion drive. The world is waiting for a good inertia-control gadget. Once you can reduce an object's inertial mass to .001 of its original value, the ion drive comes into its own.

"The engines put out about ten pounds of thrust overall, Lieuenant Mary Sue, but then again when the Armbruster Generator is on, the ship has an effective mass of just 1.6 ounces. Stand by for one hundred gees."

***

Tony said...

Bruce Lewis:

"Once you can reduce an object's inertial mass to .001 of its original value, the ion drive comes into its own."

Except that when you do that, nuclear physics breaks down and everything in the field disintegrates.

Jim Baerg said...

Anyone think low acceleration drives resulting in travel times of months between planets are a problem for story telling, perhaps should read a few tales from the days of sail when it often took months to travel between continents.

Tony said...

Jim Baerg:

"Anyone think low acceleration drives resulting in travel times of months between planets are a problem for story telling, perhaps should read a few tales from the days of sail when it often took months to travel between continents."

Or just read a Heinlein juvenile. Good writing overcomes long transit times, no sweat.

Thucydides said...

A bit of clever engineering can help. Since the acceleration is failrly sedate, but ultimate velocity can be quite high (think back to examples using solar sails with accelerations in the order of 1mm/S^2), we really need a means to rapidly decelerate.

Plunging into a planetary atmosphere to aerobrake, trailing a magnetic sail to interact with the Jovian magnetosphere or using a high thrust/low ISP rocket to do the job (probably the worst option) would all work to slow your interplanetary ship down to mere orbital velocities. Of course these means all exist for any realtech drive system.

As for inertialess magitech drives, I suspect that if you can manipulate the Higgs field to eliminate inertia, you might also have a means of reactionless drive (with all the various bad things tha would imply)

Rick said...

Welcome to a new commenter!

I (hazily) recall something about cross sectional limits, such that an ion thruster array capable of producing, say, 1 kN of thrust - pushing a 100 ton spacecraft at 1 milligee - would have to be ridiculously wide.

Pretty much what Ferrell mentions.

For cinematic combat maneuvers, electric drive of any sort has a severe drama deficit.

Actual deep space travel is quite another matter. One milligee puts on pretty close to 1 km/s per day - a 30 day departure burn, 30 days coasting, and a 30 day arrival burn gives you a total delta v of ~50 km/s, peak speed of 25 km/s, and takes you nearly 1 AU in flat space.

An odd fact about Heinlein is that many of his midfuture classics, including the juveniles, have slower travel than that, unless they were in the torchship era. But he still favored jolting accelerations.

Apart from Oberth boot - not that big a deal if you have delta v in the dozens of km/s - high acceleration requires enormous power with not much reduction in travel time. You might want it for military reasons; for civil travel, not so much.

Bruce Lewis said...

@Tony June 7, 2011 3:50 PM; when you do that, nuclear physics breaks down and everything in the field disintegrates.

You forget that the Armbruster Generator's spinning twin microsingularities displace the mass within the field into an adjacent metric... no physics breakdown occurs except at the interface, which creates the cool "space rainbow" effect we all know and love.

Teleros said...

Thucydides: "As for inertialess magitech drives, I suspect that if you can manipulate the Higgs field to eliminate inertia, you might also have a means of reactionless drive (with all the various bad things tha would imply)"

Eliminating inertia is generally going to be a Bad Thing to do - unless you want it as a weapon, that is. If you do it Doc Smith-style (existing velocity is "suspended" whilst the inertialess drive is active), you've just turned the atmosphere in the entire ship into a light dusting of atoms on the floor, various biological processes won't work (pumping blood will be "fun" for your heart now), and I even heard that it'll screw up little things like electron orbits and the wavelengths of photons (ie, you won't be able to see, and your optronic / photonic computer won't work either). A couple of options for the Doc Smith version working are that it's more of a space-warp the contents of which are inertialess relative to the rest of the universe, or that it only works on things of a big enough mass (like humans, bullets, starships etc, but not say red blood cells or N2, O2 & CO2 molecules :P ). At least Doc Smith had the sense to come up with a magic exhaust that worked when the ship was inertialess ("4th order corpuscles", according to Galactic Patrol).

Still, I like the idea of an inertialess-warhead-armed-missile as a weapon... :) . It's the sort of thing I'm surprised Stephen Baxter never used for his Xeelee & Silver Ghosts.

Back on topic with ion drives, I believe most of the Star Wars ships are said to use them (TIE fighters, star destroyers, etc), but as in the OP, everything I've read suggests that they're best used for journeys where you don't mind taking forever to get there. As far as the need to get electric power goes... perhaps very efficient solar panels, and / or a ground-based laser / photon drive? Hmm, it says something that I'm already considering the ion drive as an adjunct to more powerful means of propulsion...

Tobias said...

I hope you are being hyperbolic, and know that second generation lithium batteries are often referred to as lithium ION batteries. And to my great surprise nobody had the idea to call the third generation lithium, trilithium.

I don't really understand why ion drives can't be scaled up.

Teleros said...

Tobias: see here as to why scaling up is an issue:

http://www.projectrho.com/rocket/enginelist.php#ion

Tony said...

Tobias:

"I don't really understand why ion drives can't be scaled up."

Teleros:

"Tobias: see here as to why scaling up is an issue:

http://www.projectrho.com/rocket/enginelist.php#ion"


You can only get so much out of an individual thruster. Numerous thrusters can be run in parallel, which gives you a roughly linear scaling dynamic. Of course, the real limitation is still how much electrical power you can apply for propulsion. Also, you have to accept milligee accelerations, which has issues around planets.

Anonymous said...

(SA Phil)

I have thought a little bit on this. The "Efficiency" of the drive is basically proportional to the power, as is the thrust.

So instead of having a constant 0.001G thrust, does it make any sense to pulse for .1 seconds every second?

At some power point could you not use something like a Linear Particle accelerator/ Linac for thrust?

Or would the added capacitor Mass ruin the system (perhaps it would work in a Laserstar or Railgun equiped warship which needs the capacitors anyway) ?

Tony said...

SA Phil:

"So instead of having a constant 0.001G thrust, does it make any sense to pulse for .1 seconds every second?"

There are hard physical limits on thrust. Too high an ion volume in the thruster's accelertion cavity and you wind up with arcing and other energy robbing effects.

Tony said...

Rick:

"An odd fact about Heinlein is that many of his midfuture classics, including the juveniles, have slower travel than that, unless they were in the torchship era. But he still favored jolting accelerations."

It's more remass efficient to dump as much overboard as possible, as quickly as possible. Also, for Oberth maneuvers, you want to do as mcuh of the thrusting as possible at the lowest point in the trajectory. Higher accelerations aid this.

Anonymous said...

=Milo=



Bruce Lewis:

"The world is not waiting for a good high-thrust ion drive. The world is waiting for a good inertia-control gadget."

Unfortunately, the good high-thrust ion drive is the only one that doesn't break the laws of physics. Conservation of mass, conservation of momentum, remember? The chances of us finding a way to toy with that on a whim is at least as small as the chances of us discovering faster-than-light travel. And I'd rather have the latter if I had to choose.



Rick:

"Apart from Oberth boot - not that big a deal if you have delta v in the dozens of km/s - high acceleration requires enormous power with not much reduction in travel time. You might want it for military reasons; for civil travel, not so much."

Except, of course, for travelling between space stations in the same planetary system, or the like. And for surface-to-orbit launch, of course.

But yeah, high-acceleration engines aren't very useful for civilians, unless you're up in the torch range where you can put out 1 gee for weeks on end.



SA Phil:

"So instead of having a constant 0.001G thrust, does it make any sense to pulse for .1 seconds every second?"

I don't think so. The entire point here is that while ion thrusters can provide a lot of delta-vee, they can't supply much of it in a short burst, so they need to work continuously.

However, with an ultracapacitor to "save up" the energy your nuclear plant (or whatever) produces over each second, there might be some advantage to it, depending on details of the ion thruster design that are beyond my understanding.

Anonymous said...

(SA Phil)

Yeah I wasnt thinking Ion so much as other electrical thrusters that might benefit from having very high power.

Which led me to wonder on some kind of particle accelerator which might ordinarily require too high power to use for an electric drive, but if you pulsed it, maybe it would be feasible.

Linear Particle Accelerators have fairly high efficiencies.

At a few tenths of a gee pulsed acceleration might feel more like ocean waves than anything jarring.

Thucydides said...

"Surfatrons" might be a way of building a compact plasma drive, since they can accelerate ions to huge energy levels in millimeters.

The thing about most current forms of ion propulsion is they need a large amount of energy, so the generator becomes a large mass burden. If the receiver technology can be made light enough, then off board beamed power would make ion drives much more practical (there would be no need to accelerate the mass of the energy source, since it is safely at home).

Tony said...

Thucydides:

"The thing about most current forms of ion propulsion is they need a large amount of energy, so the generator becomes a large mass burden."

That's actually not the case. Ion motors are very energy efficient, with Isps in commercial models running 2300+ sec. The problem is that they're such low thrust you have to gang a lot of them together and supply them with a lot of electricity. how you do that is nuclear, solar, or whatever. But the real challenge is orbitting a large enough power source with a high enough energy density. Whether you use beams or wires to transfer the power from the generator to the motors is orthogonal to ion motor efficiency. You'd have the same issues with VASIMR or anything else that used electricity.

Nyrath the nearly wise said...

Apropo of nothing, I remember one occasion where Arthur C. Clarke obliquely alluded to an ion drive. In EARTHLIGHT, the spacecraft propellant was "finely divided dust". This would make them some species of colloidal ion drive.

Tony said...

Nyrath:

"Apropo of nothing, I remember one occasion where Arthur C. Clarke obliquely alluded to an ion drive. In EARTHLIGHT, the spacecraft propellant was "finely divided dust". This would make them some species of colloidal ion drive."

Yep, and IIRC, Moon dust was the preferred remass. But that story also had supermagitech spacedrives that imparted Area 51 UFO type maneuverability.

Jim Baerg said...

IIRC the supermagitech drive was an *extremely* recent development & all the previously existing spacecraft used moon dust reaction mass.

Tony said...

Jim Baerg:

"IIRC the supermagitech drive was an *extremely* recent development & all the previously existing spacecraft used moon dust reaction mass."

[quibble]It was experimental and only installed on three warships at the climax of the plot. By the epilogue, however, it was a few decades old and in widespread use.[/quibble]

Of course, had Clarke written the story today, there probably wouldn't have been a tactical battle taking place over a million or so cubic miles of space above the lunar surface. The Federation ships would have run out to the Oort cloud, turned around, and made an RKV run against their objective.

Anonymous said...

Tony,

You'd have the same issues with VASIMR or anything else that used electricity.
==========

This is essentially the limitation I was working with.

If I need a lot of energy to do something, the most practical way is to charge a capicitor first.

That allows my momentary energy level be extremely high.

So a 100 MW Fission reactor could fire off a GW worth of electric propulsion for one second out of every 10.

Or 100 GW 0.01 seconds out of every 10.

The average power use is roughly the same.

It works the same way on the low end. Your Solar powered Ion drive could be a 100 Watt unit that operates continuously or a 1000 Watt unit that fires intermittantly.


(SA Phil)

Thucydides said...

It has been a long time since I read Earthlight, but Clarke did have it right in the sense the battle was taking place over a volume of millions of kilometers rather than essentially point blank range like we see in most movies and TV shows.

Yes, running in at high fractions of c would have been much more sensible from a tactical point of view, but didn't the Asteroid Federation need to capture the Moon to get access to the rare McGuffinite? A huge molten crater does not seem to be the best way to achieve this goal....

Rick said...

Regarding Earthlight, my recollection was that the range was actually pretty short, so that the protagonist, himself somewhere on the lunar surface, was able to visually watch the battle between the three Martian warships and the mass driver fort on the lunar surface.

Since the main characters were not part of the fighting forces, Clarke was able to slide past doctrinal and tactical issues. I haven't read the book in eons, but why were the Martian ships even engaging the fort? They might instead have cut the Moon off from effective Earth control with blockade, etc.

Of course the real reason was that Clarke wanted to try his hand at a semi-operatic space battle.

Tony said...

I just reread the final few chapters of Earthlight last night. The Earth fortress on the Moon was built over a deep mining project (100 km deep, with "silicone oil" at high pressure used to resist cave-ins). The Federation wanted to destroy it to deny it to the Earth. The Federation ships fought at ranges up to 100 km, but often at much shorter distances. This was because Clarke envisioned energy weapons as something like high powered microwave cannon, which made them succeptible to the inverse square law. So the attacking ships got as close as they could without getting too close.

Nyrath the nearly wise said...

Yes, when he wrote EARTHLIGHT, Clarke was very aware of the inverse square law. EARTHLIGHT was written quite a few years before the invention of the laser.

jollyreaper said...

Track

Brian/neutrino78x said...

To the author of the blog, dude, I know you're new to the bay area! But, I thought I would point out, our nickname is not "Babylon by the bay", but, rather "Baghdad by the Bay". Check the wikpedia entry for SF, on the right hand side, where it lists nicknames. :)

http://en.wikipedia.org/wiki/San_francisco

The reason is the diversity and tolerance of the Bay Area.

It is a reference to the way Baghdad was before Saddam Hussein (especially, ancient Baghdad): it was a cosmopolitan city, known for Muslims, Jews, and Christians partying together, and it was also a great port city, where all cultures could be found in a small space! That's how the Bay Area is too!

btw make sure you never refer to highways like 101 as "the 101", people will know you're not from here. ;-) Here in SF Bay, we just say "101". lol

what else...uh...don't ever say "Cali", up here we say "California". You can say "norcal", just not "cali". The latter is something they say in LA.

LA and the Bay have a long standing rivalry, going back at least 50 years; in the Bay, we regard southern California (with the exception of West LA/Hollywood) as The Evil California, for political reasons! lol. For example there was a big lawsuit over which is the real Surf City (As in the beach boys song), between Huntington Beach and Santa Cruz (yes, SC is technically not part of the Bay, but spiritually, we are allies). Unfortunately, Huntington Beach won the lawsuit. :-( lol ;-)

--Brian

Tony said...

Brian:

"To the author of the blog, dude, I know you're new to the bay area! But, I thought I would point out, our nickname is not "Babylon by the bay", but, rather "Baghdad by the Bay"."

It's also called "Sodom by the Bay" by a lot of people. "Baghdad by the Bay" is self-aggrandizing spin.

"btw make sure you never refer to highways like 101 as "the 101", people will know you're not from here. ;-) Here in SF Bay, we just say "101". lol"

BTW, I was born and raised in California and I used to drive on "the 10", "the 210", "the 57", and, yes, "the 101".

"what else...uh...don't ever say "Cali", up here we say "California". You can say "norcal", just not "cali". The latter is something they say in LA."

Bay Area parochialism certainly doesn't speak for everyone from California. And I doubt Rick is so shallow as to want to appear like a native.

"For example there was a big lawsuit over which is the real Surf City (As in the beach boys song), between Huntington Beach and Santa Cruz (yes, SC is technically not part of the Bay, but spiritually, we are allies). Unfortunately, Huntington Beach won the lawsuit. :-( lol ;-)"

Not being a surfer or ever having lived in either of those cities, I am agnostic about this. But it is a fact that "Surf City" was a Jan and Dean song whose lyrics were written by Brian Wilson. Both The Bach Boys and Jan and Dean, being from LA, are likely to have surfed Huntington Beach much more as youths than Santa Cruz. (Of course, if you ask the Brian Wilson, Jan and Dean weren't even surfers.) Also, Dean Torrence was the person who originally suggested Huntington Beach call itself "Surf City". That's pretty authoritative. Finally, it's hard to imagine any beach in the Bay Area having "two girls for every boy". Nothing personal in that, it's just that Northern California is too cold and the beaches aren't sheltered by islands like the LA beaches are. It just seems less likely that you'd find quite so many sunbathing girls on them.

neutrino78x/brian said...

Tony, by "from here" with regard to highway references, I meant "from the bay". ;-)

"the 101" is a southern California phrase. We drop "the" up here. :)

Also "baghdad by the bay" is a compliment, referring to our diversity and tolerance in the Bay Area (people get confused by this moniker because they think of Saddam Hussein, but one must remember that, historically, before he came to power, Baghdad was a cosmopolitan place), it is normally attributed to Herb Caen, a famous SF Chronicle columnist; he referred to it that way in 1949, long before Hussein. :)

see the wikipedia entry on him, under "Herb Caen Way..."
http://en.wikipedia.org/wiki/Herb_Caen

Tony said...

Re: Brian

I encourage everyone to read the article you linked to. I personally think the best part is how Caen willed part of his estate to pay for a fireworks display in his own honor.

Brian said...

lol Caen was a character! I've read his columns a couple times. I like San Jose (Silicon Valley) a little more than SF itself, since I am actually from Silicon Valley, but the whole Bay Area has a similar cosmopolitan outlook. San Francisco Bay is a huge body of water, about 70 miles (100+ km) in length. :) I knew this guy in the Navy who was from Sacramento, he claimed San Jose is not in the Bay Area because it "doesn't touch the bay", and I had to explain to him that it does. In fact, San Jose used to have a deep water port (the Alviso neighborhood), but when they built the railroad between SJ and SF in the 1850s, they started to fill in the port. People have been trying to restore it lately, at least for boat launches, and to restore the marshes.

Brian/neutrino78x said...

btw another thing I thought of for the owner of the blog: it is a requirement for all residents of the SF Bay Area to go and watch Beach Blanket Babylon at least once!!!!! It is a live comedy/musical show about politics.

http://www.beachblanketbabylon.com/

Tony said...

Brian:

"lol Caen was a character!"

That's not quite what I was getting at, B...

Anonymous said...

(SA Phil)

So if I am following this right, the anecdotes meant to lead to the discussion have become the subject of discussion.

Anonymous said...

Re: San Francisco being part of nothern California.

I'm originally from Eureka on Humbolt Bay, and we don't concider SF or Sacramento to be part of 'Northern' California...they're both part of the south. Some people still would like the state to be split, with SF Bay being on the northern most edge of the State of Southern California...not that it has a hope in hell of ever happening, but you know how people like to hang on to impossible dreams... ;)

Ferrell

Tony said...

Ferrell:

Economically, culturally, and socially, northern California begins somewhere between Bakersfiled and Fresno. For example I used to work with a woman from the Fresno area. She considered herself to be from the northern part of the state.

Also, I think you need to review a map. Sacramento is significantly further north than the San Francisco Bay area.

Anonymous said...

Tony; I know where Sacramento is, both physically and politically. Perhaps you should look up pre-WWII history of California WRT the movement to seperate the state in two. You might find it enlightning.

Ferrell

Tony said...

Ferrell:

"Tony; I know where Sacramento is, both physically and politically. Perhaps you should look up pre-WWII history of California WRT the movement to seperate the state in two. You might find it enlightning."

There have been so many proposals for dividing California that any one proposal, even including its history, is hardly proof of anything.

Anonymous said...

(SA Phil)

Maybe we never should have stolen California from Mexico

Tony said...

SA Phil:

"Maybe we never should have stolen California from Mexico"

The Mexican governor and military commandant in Alta California ran away before they were even attacked. The entire region of the Mexican Cession (including Nevada, Utah, and parts of Arizona, New Mexico, Colorado, and Wyoming) was basically defaulted to the US by a Mexican government trying to protect its sovereignty in Mexico proper. Rather than stealing, it was more a case of picking up all of the pieces left unattended.

In any case, Phil, haha, very funny. But the real options were either take over the territories of the Cession, or deal with an independent California, Deseret, and who knows what other states that might have been declared. Mexico wasn't getting back in. And all of those places would eventually have become US states anyway.

Thucydides said...

A very long time ago there was a book called "The Nine Nations of North America". While it is somewhere in storage now, I do recall after reading it that the author's divisions mirrored the various climactic zones of North America (with the obvious exception of Quebec). Northern California, in this model, was attached to the coastal rainforest zone which runs up the West Coast of North America to the Alaskan Panhandle, and viewed economically, socially and politically as part of a unit called "Ectopia". San Fransisco was considered the regional "Capital".

Southern California, with it's limited rainfall and dependance on irrigation was considered to be part of "Mexamerica" The climactic argument might be a bit difficult to sustain, but the social and economic integration made some sense at the time.

With changing times, the map has fractured. Texas is no longer part of "Mexamerica", for example, but integrated with the energy producing "Empty quarter". Robert Kaplan's "An Empire Wilderness" also suggests that ecological boundaries are important ways to delimit the range and influence of various polities, although his view seems to be more focused on urban and exurban areas, with each unit acting almost as a City State sometimes at odds with the nominal State capital or the Federal government. Kaplan's model rewards the studies of watersheds.

Tony said...

You know, everybody touts centrifugal forces that are supposed to be pulling the US apart, but, even having grown up and lived most of my life in California, I still have more in common with somebody in Boston or Dallas than I do with people in Japan or Australia. I'm pretty sure that's true for most people, wherever they live in the states.

Rick said...

I deliberately picked Babylon instead of Baghdad because Real Life has somewhat eclipsed the Baghdad of Romance. Babylon had nearly the same connotation in its day, after all, and don't forget Beach Blanket Babylon on its various incarnations.

And yes, I'm aware that 'the 101' is a Southern California-ism. But rooting for the Giants instead of (kinda sorta) the Dodgers is a much more sweeping transformation!

(Actually I grew up in San Diego, but never related much to the Padres.)

'Cali' is a strange usage I don't relate to at all.

For most of my adult life I lived on the Central Coast. Pismo Beach is distinctly a Southern California beach town, while Morro Bay is just as distinctly a Northern California fishing port, which puts SLO Town almost exactly on the dividing line, at least near the coast.

In the modern era, though, the cultural division of California is much more east-west than north-south, with the dividing line corresponding fairly closely to US 101. Western CA is blue-state, eastern CA much more red-state, in both voting behavior and general cultural stereotypes.

Tony said...

Rick:

"But rooting for the Giants instead of (kinda sorta) the Dodgers is a much more sweeping transformation!"

San Francisco is much more like Boston or New York when it comes to baseball than it is like other California cities. Rooting for the Giants is a bit more, ummm...fanatical. In LA, when I was a kid, you went to Dodger stadium to see the Dodgers, but you went to Anaheim Stadium (most of the time) to see the Yankees or the Royals. In any case, whichever LA area team made the playoff -- or if they both did -- it was okay. It's hard to imagine Giants fans supporting the Athletics simply because they were doing good.

"In the modern era, though, the cultural division of California is much more east-west than north-south, with the dividing line corresponding fairly closely to US 101. Western CA is blue-state, eastern CA much more red-state, in both voting behavior and general cultural stereotypes."

I think the north-south distinction is still important to a lot of Californians. I know for a fact that it's important to business, which usually divides California into a northern region managed from somewhere in the Bay Area, and southern region, managed from somehwere in LA or Orange County.

Having said that, I have to agree that the east-west division in California politics is second only to the north-south economic division in deciding how people think and act. For example, the San Gabriel Valley, east of Downtown LA, is generally conservative, while the San Fernando Valley, northwest of downtown is decidedly liberal.

Thucydides said...

You can divide areas as finely or coarsely as you want to prove a point. My home town can be divided into various subdivisions based on industry, demographics, wealth, voting patterns and so on. Not all the borders are mutually overlapping either.

Still, there are distinct "regional" differences between places. Getting back to Rocketpunk for a moment, I can see distinctions in the Rocketverse between people who inhabit space colonies and those who choose to live on planets and moons. Even people in orbital structures associated with a particular body might be closer to their free space bretheren due to similar challenges and lifestyles than the "groundhogs" below.

Tony said...

Thucydides:

"Getting back to Rocketpunk for a moment, I can see distinctions in the Rocketverse between people who inhabit space colonies and those who choose to live on planets and moons. Even people in orbital structures associated with a particular body might be closer to their free space bretheren due to similar challenges and lifestyles than the "groundhogs" below."

Would people inhabit space habitats in any large numbers? Such structures require huge resources yet have no known economic justification. They're certainly not going to be built with any current or reasonably forseeable technologies. And if one had the thechnological and economic resources to build large space habitats, why would one not invest them in a place a lot easier to live, like the surface of Mars?

I know all of this sounds pesimistic and in a way almost sacriligious to space enthusiasts of a certain age and long standing. But it's actually intimately related to the topic's subject -- ion propulsion (and solar/nuclear electric propulsion in general) is a technology of use to people who don't really have a lot of resources for space travel and living. Most people riding ion rockets in the PMF are going to be going one-way, probably to Mars. They're not going to be living in space habitats for the simple reson that space habitats of O'Neillesque ambition rely a lot more on magitech than was once thought.

Thucydides said...

The PMF and the Rocketverse are two different places. While we will certainly live to see some manifestation of the PMF (even if it turns out to be the Chinese/Indian rivalry over setting up a Moon base), for the purposes of most discussion on this blog we have to default to the Rocketverse, where there are people and (unspecified) economic activity to support the various tropes.

Anonymous said...

=Milo=



I don't think space stations are ever going to reach "civilization" sizes, barring magitech. If space stations exist, they will be things like ports - somewhere that most people just pass through with no intent to stay, and the few that do stay there are employed in the business of providing services to the people who do, with their income deriving entirely from trade. You can't have thriving trade centers without having someone producing the goods being traded. Those people need to live on a planet (or moon).

Tony said...

Thucydides:

"The PMF and the Rocketverse are two different places."

And both equally valid contexts of discussion WRT Rocketpunk. One is the techno-fantastic version, the other is the techno-realistic version. I doubt I'm alone in preferring reality over fantasy.

Jim Baerg said...

Does an O'Neill type space colony really require any more magitech than a colony on the suface of Luna or Mars?

If the O'Neill habitat is adjacent to a small asteroid made of a mix of stone metal & volatiles I would think the difficulties to be less than for a moon or Mars base. Certainly power supply is easer for the O'Neill.

Tony said...

Jim Baerg:

"Does an O'Neill type space colony really require any more magitech than a colony on the suface of Luna or Mars?

If the O'Neill habitat is adjacent to a small asteroid made of a mix of stone metal & volatiles I would think the difficulties to be less than for a moon or Mars base. Certainly power supply is easer for the O'Neill."


THe problem is finding the resources -- particularly energy -- and the industrial base to make the thing in the first place. How an existing habitat might fare is irrelevant. It's a case of you can't get there from here.

Jim Baerg said...

Yes Tony, getting things going off Earth is hard. I'm just saying it looks marginally less hard to do an O'Neill beside a NEO than to climb out of Earth's gravity well & then climb down into Mars' to set up an industrial base there.

Tony said...

Jim Baerg:

"Yes Tony, getting things going off Earth is hard. I'm just saying it looks marginally less hard to do an O'Neill beside a NEO than to climb out of Earth's gravity well & then climb down into Mars' to set up an industrial base there."

But it isn't. The life support, nutrition, power, and (relatively) minor construction requirements are similar. But space habitats also require the building of megastructures. Space habitats aren't less hard, they're harder -- and not marginally so.

Thucydides said...

I think there are many ways to avoid building megastructures as scaffolding for constructing the colony itself. Inflatable forms, vapour deposition of metals, even the adaptation of materials like "concrete paper" (add water and the concrete becomes pliable; once dry the concrete has set and a permanent wall or form is built). Radiation sheltering might take the form of stacked HESCO bastions, essentially wire baskets filled with earth (or in this setting, slag from processing NEO materials). Other ideas like pumping localy mined water into hollow plastic bladders to create living spaces might be exploited.

True the job will still be difficult and require many new techniques, but since people in space will have a very limited tool set due to mass limitations and lack of prior experience, you will see many adaptations rapidly taking place. Scientific expeditions to NEO's will probably be the stage where the first steps will be taken to learning new techniques, as crews park habs and work areas in or on the NEO, and these ideas will be expanded on as time goes by.

Tony said...

Thucydides:

"I think there are many ways to avoid building megastructures as scaffolding for constructing the colony itself. Inflatable forms, vapour deposition of metals,"

That might work for relatively small structures...after you figure out how to locate, extract, and refine the metals. That's not cottage industry.

"even the adaptation of materials like "concrete paper" (add water and the concrete becomes pliable; once dry the concrete has set and a permanent wall or form is built)."

Where do the cementitious binders come from? Those have to be formed in the presence of liquid water to begin with. That's kind of hard to find this side of Jupiter's orbit.

"Radiation sheltering might take the form of stacked HESCO bastions, essentially wire baskets filled with earth (or in this setting, slag from processing NEO materials)."

That kind of thin woorks much better in a gravity field. Packing for density is less of a hassle too.

"Other ideas like pumping localy mined water into hollow plastic bladders to create living spaces might be exploited."

Where do you mine water inside the orbit of Jupiter? Where do the organic chemicals for the plastic come from?

"True the job will still be difficult and require many new techniques, but since people in space will have a very limited tool set due to mass limitations and lack of prior experience, you will see many adaptations rapidly taking place. Scientific expeditions to NEO's will probably be the stage where the first steps will be taken to learning new techniques, as crews park habs and work areas in or on the NEO, and these ideas will be expanded on as time goes by."

Owing to the mass limitations, explorers will be concentrated on exploring, not homesteading. Even the National Space Society, which is a bunch of starry-eyed dreamers by many measures, puts "Construction of O'Neill Habitats" at #15 on its milestones list, after "Mars Settlement" (#13) and "Exploration & Settlement of Asteroids" (#14). IOW, it's past the PMF, perhaps way past it.

Geoffrey S H said...

We need some sort of scale to denote periods after the PMF. If PMF is up to 500 years, then what is 500 years after that? I envision the earliest cue for O'Neils being the 1000 year mark.
Maybe expanding our gaze to a 1500 year focus rather than 500 years would be useful. Sure, we're talking about the PMF, but some sort of awareness of later periods might be useful.

Rick said...

Wow, a discussion thread that spontaneously drifted back on-topic!

I think of the distinction between colonies, or even incipient colonies, and small outposts as more essential than surface v orbital. The latter would depend significantly on what your McGuffinite is.

As to what lies beyond the plausible midfuture ... a very good question. I somewhat hesitate to say 'plausible far future,' because almost definitionally it is hard to say what is or isn't plausible once you get that far out.

On the other hand, it isn't like you go straight from the PMF to spires 'n' togas. Something to think about, and maybe even post about ....

Anonymous said...

=Milo=



Tony:

"Where do the cementitious binders come from? Those have to be formed in the presence of liquid water to begin with. That's kind of hard to find this side of Jupiter's orbit."

Any conception for a long-term or short-term space habitat had better have access to ample liquid water. Fortunately, it's perfectly acceptable to acquire frozen water and melt it yourself. Also fortunately, the only places without useful supplies of water are Venus, Io, and the gas giants.


"Where do you mine water inside the orbit of Jupiter?"

Everywhere? The moon has ice. Mars has ice. Even Mercury is believed to have ice.

Granted, you do need to land your outpost in the right place (typically near the poles) for good results.


"Where do the organic chemicals for the plastic come from?"

That's a better question. While you're going to need to produce some organic chemicals (food!), they'll probably be expensive enough that bulk construction will prefer using rocks and metals rather than plastics, with the latter reserved for applications where they're strictly necessary.

Tony said...

I nominate "undiscovered country" fro the far, unpredictable future and "partially discovered country" for the PMF.

Jim Baerg said...

The very 1st space habitats can be on the scale of the ISS or the Bigelow inflatable habitats. If artificial gravity is desired two Bigelow type habitats can be connected by a tether & rotated about one another. The scale of space construction can be gradually increased (probably very gradually) to cylinders a few km across.

Whatever the scale I don't see why building something on Mars would be easier than building a space hab adjacent to Phobos.

As for finding water, IINM some if not most of the the NEOs are carbonaceous chondrite asteroids or extinct comets which would still have significant quantities of water.

Tony said...

Jim Baerg:

"Whatever the scale I don't see why building something on Mars would be easier than building a space hab adjacent to Phobos."

Because on Mars you don't have to build the ground upon which or within which everything else is constructed. Also, on Mars you have the advantage of a gravity field, which significantly implifies everything one does, from swinging a hammer to anchoring a structure.

"As for finding water, IINM some if not most of the the NEOs are carbonaceous chondrite asteroids or extinct comets which would still have significant quantities of water."

But not liquid water or even water ice. That significantly complicates extraction of H2O, and may even make it impractical. Mars has water ice and even trace amounts of water vapor suspended in the atmosphere.

Rick said...

I nominate "undiscovered country" for the far, unpredictable future

Alas, that expression has a well established and rather sober connotation.

And in that sense, even the midfuture, beyond perhaps its first few decades, will remain an undiscovered country to us!

Jim Baerg said...

Tony: "the advantage of a gravity field, which significantly implifies everything one does, from swinging a hammer to anchoring a structure."

I think the extent to which that is true will diminish with experience in space. Our current techniques have all been developed in a 9.8 m/s^2 gravity field & are adapted to that field.

Experimentation will develop techniques that work better in space than in macrogravity. Eg: glass blowing is limited to making small objects in earth's gravity, but could be scaled up substantially in microgravity. It would likely also be applicable to other materials like molten metal.

Tony said...

Jim Baerg:

"I think the extent to which that is true will diminish with experience in space. Our current techniques have all been developed in a 9.8 m/s^2 gravity field & are adapted to that field."

I don't. The bias that a gravity field exerts on processes is simply taken for granted by most people. Our experience of working in space has educated us that it shouldn't be. I mentioned swinging a hammer for the reason that such a simple and ubiquitous task requires gravity to work with any kind of useful effciency. The simple act of setting something down and expecting it to stay where it's put is only possible in a gravity field (or an accelerated frame of reference that mimics one). The same goes for all sorts of gravity-based processes that we normally don't think about, but all of which would be impossible in microgravity.

"Experimentation will develop techniques that work better in space than in macrogravity. Eg: glass blowing is limited to making small objects in earth's gravity, but could be scaled up substantially in microgravity. It would likely also be applicable to other materials like molten metal."

Actually, blowing large pieces has severe wall thickness consistency issues that limit it more than gravity droop. Microgravity is not going to eliminate that.

Setting aside a small minority of techniques that microgravity might improve, microgravity will inhibit the vast majority of industrial techniquies.

Jim Baerg said...

Tony: I guess we just need a few more decades of experience in doing things in space before we 2 can do an anything more than agree to disagree.

Thucydides said...

Many techniques that early habs, labs constructs and colonies will be built out of will consist of leveraging small amounts of materials that you bring from Earth (answering the question of where does the plastic come from; you brought the bladder and are now filling it with locally procured water).

From what I understand from the literature, water in asteroidal material can be extracted by heating the material in a container and condensing the escaping vapours. The container, solar mirror and metaphorical shovel are the things you bring along with the plastic bladder, for a small and versatile tool kit (the mirror can be focused on your solar collector when you are not distillig water or melting glass...).

In the PMF, Rocketverse and even in the distant future, people and their post human descendants will probably strip down the current industrial toolboxs to minimize mass, emphasise multiplexing, simplicity and modularity. Discussions about the benefits of assembly line production of screws vs steriolithography will be moot becase people are using a solar mirror for heat welding parts.

Tony said...

Thucydides:

"Many techniques that early habs, labs constructs and colonies will be built out of will consist of leveraging small amounts of materials that you bring from Earth (answering the question of where does the plastic come from; you brought the bladder and are now filling it with locally procured water)."

Small habs and labs in free space I can see. Colonies? Not a chance. To the degree that any colonies ever exist off of Earth, for many hundreds or thousands of years they will be on planets or large moons. There's just nothing in space worth living there for.

"From what I understand from the literature, water in asteroidal material can be extracted by heating the material in a container and condensing the escaping vapours. The container, solar mirror and metaphorical shovel are the things you bring along with the plastic bladder, for a small and versatile tool kit (the mirror can be focused on your solar collector when you are not distillig water or melting glass...)."

Shovel? In microgravity?

Solar mirror? How large, how reflective, what energy flux at the focus, how much energy flux in what area around the focus? Use a mirror good for melting out metals is going to be overkill for outgassing water.

And what else is going to outgas with the water? How do you separate it? Why not just melt relatively pure water ice or ditill water vapor out of the air on Mars?

These aren't questions seeking answers, BTW. They're rhetorical, designed to illustrate how simplistic and ill-considered the standard O'Neillesque narrative is.

"In the PMF, Rocketverse and even in the distant future, people and their post human descendants will probably strip down the current industrial toolboxs to minimize mass, emphasise multiplexing, simplicity and modularity. Discussions about the benefits of assembly line production of screws vs steriolithography will be moot becase people are using a solar mirror for heat welding parts.

Heat welding parts? Really? Welding isn't even an acceptable method of joining for many assembly applictions. It's imprecise, causes parts to heat distort, and makes assemblies too hard to disassemble. One of the big reasons you use fasteners is that you want to take the assembly apart at some time in the future. You only weld (or glue or otherwise bond) stuff you never expect to disassemble again. Fasteners and their associated tools will always be in the human toolkit.

As for multiplexing, what is the motivation behind doing several jobs poorly with one tool, rather than doing them all well with the appropriate tools? Simple mass restrictions? When you get to the point of establishing an industrial base, in space or anywhere else, you'll have the resources to build it up properly.

Tony said...

Jim Baerg:

"I guess we just need a few more decades of experience in doing things in space before we 2 can do an anything more than agree to disagree."

Ever watch an equipment repair or installation spacewalk on NASA TV? I have, several of them, all the way through. I commend it to you. I think you will agree with me after watching even one EVA that there's no "few more decades of experience" (or centuries) that's going to make any of that as routine as doing something as simple as mounting a license plate on a car, much less anything that takes real skill and precision.

Anonymous said...

=Milo=



Thucydides:

"In the PMF, Rocketverse and even in the distant future, people and their post human descendants will probably strip down the current industrial toolboxs to minimize mass, emphasise multiplexing, simplicity and modularity."

I expect colonists will utilize bootstrapping - they bring with them some lightweight tools which they can then use to build more advanced tools using locally procured materials.

This requires being smart enough to settle somewhere that has locally procured materials, like a planet.



Tony:

"Ever watch an equipment repair or installation spacewalk on NASA TV?"

Those have issues arising from the lack of atmosphere, the consequent need for a spacesuit and its overly thick gloves, and the extremely delicate maneuvering that arises from being outside the station proper.

In a hab people will probably spend far more time tinkering with equipment and room structures inside the hab than they will venturing outside it.

Anonymous said...

How about 'the possible far future'?

Building habitats on/within asteroids and dwarf planets might combine the best features of surface habitats (abundant raw materials, gravity high enough for hammering/anchoring etc.) and orbital habitats (shallow gravity well, gravity low enough not to interfere with rotational artificial gravity).

I suspect that such 'dug-in' habitats, and probably the modular 'beaded habitats' conceived in a NASA study, will be constructed long before the classical O'Neill habitats, unless some means of rapidly constructing a large hollow shell, such as the Bubbleworld/Cole Habitat concept, is developed first.

R.C.

Anonymous said...

=Milo=



R.C.:

I think that gas giant moons would be more attractive for that purpose than dwarf planets. (And to a lesser extent rocky planet moons, although we have only one that actually qualifies, though it has a serious advantage in proximity.) You might have some trouble with the gas giant's gravity well, but at the same time you have easy access to the gas giant itself and multiple other moons. There are less dwarf planets in the entire asteroid belt than there are rounded moons orbiting Saturn, and they're scattered to the point that it's ridiculously slow and expensive to get from one to another. Meanwhile many of those moons have interesting features that make them a prime exploration target, while there are also still definitely several that are nothing more than airless balls of rock, if that's what you need. Also Saturn (or even Jupiter) gives better visuals, and somewhere deep down that's what most of us want from science fiction.

One advantage that (mainly) Kuiper belt objects do have is a higher proportion of volatiles like ammonia, which are valuable for life. But the Kuiper belt is kinda far away so I wouldn't pick it for colonization anytime soon. Atypically high-volatile asteroids, though, might attract interest.

Tony said...

Milo:

"Those have issues arising from the lack of atmosphere, the consequent need for a spacesuit and its overly thick gloves, and the extremely delicate maneuvering that arises from being outside the station proper.

In a hab people will probably spend far more time tinkering with equipment and room structures inside the hab than they will venturing outside it."


But the big difference between living on planets and building large space habs is microgravity construction in a vacuum.

Thucydides said...

For many purposes, the Space environment is actually superior to planetary environments.

Access to energy is the big factor, solar power is abundant, gas giants have powerful magnetospheres which can be locally tapped and positioning in the gravitational well can provide potential and kinetic energy for getting around. So long as you have the ability to make mirrors, the freefall environment allows you to gang arbitrary numbers of mirrors together to generate energy even in the far reaches of the Solar System, obviating the need for fissionables or mining planets and atmospheres for Duterium or 3He for fusion fuel. The entire future could be solar powered, if required.

Materials are available in the form of asteroids, planetary rings and comets, with small, low gravity moons being the next best choice, and distant objects like the Kruiper belt being last due to distance.

Gravity is literally what you make it, in a space environment you do not have to be constrained by whatever the local gravitational field is, you control it by varying the rotational velocity and diameter of your construct. In the very early part of the PMF or Rocketverse, swinging habs on tethers in the manner of Mars Direct is the simple and cost effective solution, and adding hab volume to rotating constructs to increase the amount of workshop space is a pretty obvious evolution of any space station, scientific outpost, protocolony, space navy base etc.

Thucydides said...

And going back to ion propulsion, Boeing seems to be claiming the ability to provide megawatt scale energy from solar arrays in the near future:

http://nextbigfuture.com/2011/06/boeing-makes-case-for-megawatt-solar.html

Anonymous said...

Reading both the 'space-colony' vs the 'ground colony' arguments, I've come to the conclusion that it most likely won't be an either-or choice; it'll be a mix of ground-based outposts/colonies and space-based stations/industrial structures. The exact mix will depend on both location and circumstances. Ground sites will be where most people live and work; with the space-based portion of the population concentrating on power production, some manufacturing and mining, and supporting the space transportation industry, as well as research. Those on the ground would also engage in mining and manufacturing,as well as agriculture, research, commerice, and every other public activity that goes on in a city. The mix of ground to space would probably be different between, say, Mars and Jupiter; or even Earth and everywhere else. Potential Mercury outposts or colonies would probably need more space-based power then a Titan colony, for example. Due to the fact that space-travel will most likely take long periods of time, and large amount of money, for decades to come then we should concentrate on developing long-term habatats for both space and surface outposts; because their primary purpose will probably be research and exploration until the end of this century, we probably only need industrial capabilities suficiant to support day-to-day maintainace and a very modest level of emprovement/expansion. Whether researchers take their families with them, retire in place, or start families there, outposts need to be able to support an ability to expand to support a small growth in population of permant residents. If some of them eventually develop into real colonies, then great; if not, then they still serve their primary pupose.

Ferrell

Anonymous said...

=Milo=



Thucydides:

"Access to energy is the big factor, solar power is abundant,"

No more abundant than on an airless world, especially if you settle on a "peak of eternal light" near a pole. (Poles are also where said worlds have their ice deposits, so that's two reasons to choose those spots.)

Also, access to even better energy sources, like uranium-235 or helium-3, is greatly inferior.


"gas giants have powerful magnetospheres which can be locally tapped"

Which also saps into your orbital energy. To hold your position, you need to spend as much energy on propulsion as you earned in the first place, giving you a zero-sum game.

Better would be to generate your energy with solar or nuclear means and then feed it into a magsail or electromagnetic tether to maneuver.

Also, wouldn't the magnetic fields be accessible on moons too? Those have the mass to not have to worry about the orbital decay thing.


"So long as you have the ability to make mirrors, [...] obviating the need for fissionables or mining planets and atmospheres for Duterium or 3He for fusion fuel."

Right, but now you have to mine them for silica (for glass) and aluminium/silver to make the mirrors with. Or whatever your space mirrors are made of.



Ferrell:

"Reading both the 'space-colony' vs the 'ground colony' arguments, I've come to the conclusion that it most likely won't be an either-or choice; it'll be a mix of ground-based outposts/colonies and space-based stations/industrial structures."

I actually agree. It's likely that people will find reasons to build space stations, it's just that I think they will be specialized installations, not primary population centers. At best, a few really successful stations might become the Trantor/Coruscant equivalent (at a more sane size), entirely reliant on imports from the huge number of people on planets/moons.


"The exact mix will depend on both location and circumstances. Ground sites will be where most people live and work; with the space-based portion of the population concentrating on power production, some manufacturing and mining, and supporting the space transportation industry, as well as research. Those on the ground would also engage in mining and manufacturing,as well as agriculture, research, commerice, and every other public activity that goes on in a city."

Sounds reasonable enough.


"The mix of ground to space would probably be different between, say, Mars and Jupiter; or even Earth and everywhere else."

I don't know how many outright space stations Jupiter will have, but if both Ganymede and Callisto have been settled, it'll have a lot more space traffic than Mars. Even if only one moon has been colonized in full, there'll still be a lot more cheap scientific missions to other moons. On Mars, Mars itself is the most important thing to research, Phobos and Deimos are boring by comparison.

As for Earth, it actually has incredible difficulty reaching space compared to everywhere else. We have the highest gravity of any rocky object in the solar system, and an annoying atmosphere to induce drag. This means Earth has increased incentive to keep its stuff in space permanently. It also gives Earth a reason to outsource many of its space activities to Luna.

Jim Baerg said...

"
"gas giants have powerful magnetospheres which can be locally tapped"

Which also saps into your orbital energy. To hold your position, you need to spend as much energy on propulsion as you earned in the first place, giving you a zero-sum game."

The L4 or L5 points of a gas giant - large moon pair would be good places for energy producing tethers. The drag of the gas giant's magnetic field would tend to pull the tether away from the Lagrange point, but the moon's gravity would tend to move the tether back toward the Lagrange point. This would tend to very slowly change the moon's orbit.

"Also, wouldn't the magnetic fields be accessible on moons too? Those have the mass to not have to worry about the orbital decay thing."

Yes.
Space elevators from the moon to the L1 & L2 points could use the magnetic field as a power source.

Rick said...

I tend to agree with Ferrell. The choice of surface or space will depend on multiple circumstantial factors. Why are people going there? Why did people originally go there? (Because that determines prior choices and sunken investments.) And so on. One size certainly does not fit all.

Geoffrey S H said...

As we have discussed before, space stations are useful more as destinations than stop-off points. They are also not a massive use as manufacturing centres, but aas stated here, they may do some necessary on-site manufacturing for communities that might reside there briefly for scientific purposes.

Therefore: InternetHub modules.
Small manufacturing modules.
Observation posts.
Antennae and communications modules for controling scientific drones in the area andf remote mining craft (that's probably post PMF though due to currnt lack of uses for space mining).
Small hab modules.
Small-scale porpellant depots.
Birthing cradles with protective sheets for keeping excursion craft safe from weather (I.e.: solar flares, micrometeorites,anything else we have yet to encounter).
Excursion craft for going to other stations nearby or visiting nearby orbital bodies if that option is available.

Nothing massively ambitious for a rocketpunk future, research and space training will probably remain the focus, but other uses of such installations outlined by others such as power production and supporting the space industry should creep in gradually, even if their only role is to keep an eye on nearby powersats.

If I may offer a timeline of a reasonable nature:

2300, increase in number of earth stations to about 10 or so, scierntific and training purposes. One or two around the moon for the same purpose, and to support more hefty science installations on the moon.

2400 powersats monitered, and sometimes attached to such stations. Increase to aroundf 30. Gradual spread of such stations to Jupiter and Saturnine moons. 5 or 6 there.

2500-2600. Communities begin to expand. Limited asteroid mining- mostly scientifiuc, but some used for the needs of the communities there (though for community, read "100 or so per station at most). Interplanetary travel is easier than now, but surface to space transport still remains the infernal bottleneck to a truly rocket punk future. Some room for varied stories amongst such communities though.

As for stuff beyond the pmf, I go for the "possible medium future" from 2500-3500, and the "possible far future" for anything beyond that. 1500 Ad in the past I might be able to survive in. 500 Ad less likely but still possible. Anything beyond that would require more knowledge than my potential university degree could offer.

Therefore, in the opposite direction, the futurer, I'm beginning to serious look at 1000 years rather than 500. The PMF doesn't seem quite space opera friendly enough.

Geoffrey S H said...

Oops, sorry, forgot to add: Mix a small number of these listed modules together to get a station of choice for each location, add a little extra stuff if necessary.

Tony said...

Thucydides:

"And going back to ion propulsion, Boeing seems to be claiming the ability to provide megawatt scale energy from solar arrays in the near future..."

Not quite -- a Boeing representative speculates (without much justification that I can see) that solar electric propulsion will reach the megawatt threshold in 20 or so years, if given enough funding and basically if it is committed to as the interplanetary propulsion architecture for the future. Corporate R&D employees do this all of the time, and it doesn't mean anything.

Having said that, solar electric propulsion is a proven technology in interplanetary applications, and there's nothing fundamental standing in the way of scaling it up to relatively high impulse applications. But it has to be comitted to by both industry and government, or else it's just another conceptual toy.

Tony said...

Thucydides:

"Gravity is literally what you make it, in a space environment you do not have to be constrained by whatever the local gravitational field is, you control it by varying the rotational velocity and diameter of your construct."

Having a constant field strength is a small price to pay for having a field available whenever and wherever you want it, without having to expend energy to create it.

Anonymous said...

Many people seem to be overlooking the first form of MacGuffinite that has already been exploited, namely orbital real estate. The second form of MacGuffinite, microgravity research, is currently being mined by the ISS and, presumably soon, private industry research stations.

Although many people have floated various ideas about possible manufacturing in microgravity, it is far too early in the process to judge the long term forecast. A parallel from recent history is the path from ArpaNet to the Internet to the myriad of commercial applications we see today.

No one had any idea during ArpaNet days that blogs were going to become a major form of information exchange, or that a company built around a search engine technology might become an enormously profitable business.

Similarly we have no clue at this time what the exact form of manufacturing MacGuffinite will emerge from microgravity research that is going on now and will in all likelihood continue at an ever increasing pace. Yet to boldly claim there will be no such MacGuffinite is to thoroughly underestimate human ingenuity.

I am very confused, however, by claims that planetary colonies would be desirable. A few bases on the moon might well make sense as it is a ready source of some raw materials in a relatively shallow gravity well, but Mars, for example, makes no mid future sense whatsoever. Why, having climbed up out of a steep gravity well are we so eager to dive right back into one?

When microgravity manufacturing takes hold, if whatever raw materials are required can be gathered from the moon or from asteroids, those sources will soon become the primary sources due to the economics of gravity wells. Where industry exists, habitation will follow.

Brian61

Anonymous said...

Linking my previous post back to the topic :)

Ion drives might be entirely satisfactory in the relative near term for movement between stations and, at least for cargo, between lunar orbit and station. I wonder if a dual drive chemical (aluminum & oxygen)/ion configuration might be useful for lunar surface to station and for transport of personnel?

Brian61

Tony said...

Brian61:

"Many people seem to be overlooking the first form of MacGuffinite that has already been exploited, namely orbital real estate."

Orbital real estate isn't McGuffinite and never was. It was obvious from Tsiolkovsky on that it would have value to anyone who could claim it. McGuffinite is something that is previously unrealized and almost by definition unpredictable. And McGuffinite really only has meaning in the literary sense. In real life, and unrpedicted market for an application or resource is real enough once it has been established. It isn't just a plot device.

"The second form of MacGuffinite, microgravity research...

...Yet to boldly claim there will be no such MacGuffinite is to thoroughly underestimate human ingenuity."


Sorry, but you're working under the influence of an information hangover based on wild speculations from the 60s and 70s. Real life space operations have demonstrated that microgravity is almost usless, except as a hindrance to getting things done. I'll choose to rely on three decades of experience, rather than Space Cadet* myth.

*See
http://www.spacedaily.com/news/oped-05zzb.html

for an explanation of what I mean by "Space Cadet". (Yes, Mars colonization comes in for serious criticism in this article right along with microgravity colonization and Moon colonization, but I'll get to that in a moment...)

"I am very confused, however, by claims that planetary colonies would be desirable. A few bases on the moon might well make sense as it is a ready source of some raw materials in a relatively shallow gravity well, but Mars, for example, makes no mid future sense whatsoever. Why, having climbed up out of a steep gravity well are we so eager to dive right back into one?"

Yes, there are problems with using the surfaces of planets. It may not even be possible for humans to adapt to living on Mars. But unlike the O'Neill habitats, Mars is at least fiscally possible, if just barely. We can at least find out at a reasonable price.

"When microgravity manufacturing takes hold..."

But it won't. It is, as already stated, a myth.

Anonymous said...

Tony: I reject your authority in this matter.

Brian61

Tony said...

Brian61:

"Tony: I reject your authority in this matter."

I don't have any authority. I'm just reporting facts. There is no proven industrial application of microgravity, and we've been actively researching it for 30 years. Given the advances in other industrial and business fields over that same period -- some of them in direct competition with microgravity processes that have been tested in space (e.g. medicines such as insulin) -- I think we can make some pretty reliable conclusions. While we can't absolutely rule out some magic bullet process that would actually justify the cost of space flight to implement it, there is precisely zero evidence that a space economy could be based on microgravity.

Anonymous said...

On the timescales of theoretical research, which is the majority of what has been and continues to be done in space, thirty years is nothing. There are very likely numerous possible manufacturing processes which would be quite viable once an infrastructure is in place and costs to orbit reduce.

Yes this is speculation, but not without logical foundation. What is missing thus far is an overriding MacGuffinite, the exploitation of which would, in the short term analysis, yield sufficient profit to offset the costs of building the infrastructure. I don't think I'm bringing anything new to the table with this statement.

The conceptual situation however is that we have become so used to the rapid pace of technological innovation and process improvements in certain technologies, that we've come to expect that in all technologies. That is a doomed expectation, there is only so much low hanging fruit to be plucked.

Tony: All that said, I did not come to this venue to debate with you. Having read through a multitude of postings over the previous years of this blog, I already know that not only will you and I not agree on practically anything, but such discourse is a pointless waste of time, simply adding noise to the signal of this blog (in my opinion of course). I would much appreciate it, if you would be so kind as to ignore my posts as I will continue to do with yours, beyond this brief reply.

Thank you,
Brian61

Tony said...

Brian61:

"On the timescales of theoretical research, which is the majority of what has been and continues to be done in space, thirty years is nothing. There are very likely numerous possible manufacturing processes which would be quite viable once an infrastructure is in place and costs to orbit reduce."

First of all, what has been done in space is not theoretical, experiemtns have generally been in the proof of concept nature, because it's too expensive to do in space anything that has not been thoroughly thought out. Even with pure science platforms like COBE and Kepler, the theoretical science was well thought out before any metal was bent.

Second, you're confusing capability with fiscal viability. I have no doubt that many processes proposed for microgravity are capable -- numerous ones have been demonstrated with on-orbit experiments. What has not been shown is that they are fiscally viable with current launch vehicle technology.

Which brings us to the qualification: "once an infrastructure is in place and costs to orbit reduce". A couple of problems with this statement:

1. It's constructed backwards -- the cost to orbit has to be reduced before an orbital infrastructure can be established.

2. Costs to orbit are simply not at all likely to be reduced using current or reasonably foreseeable laucnh technologies. There will be no cheap-reliable, airline-like operations of reusable SSTO, or even TSTO. Bipropellant chemical rocket technology is over 50 years old. It's not going to improve radically in the future. And we can pretty much write off all of the megastructural (or megasystemic, like laser launch) solutions as technofantasy. There's simply no market to motivate the construction of any of them.

"Yes this is speculation, but not without logical foundation. What is missing thus far is an overriding MacGuffinite, the exploitation of which would, in the short term analysis, yield sufficient profit to offset the costs of building the infrastructure. I don't think I'm bringing anything new to the table with this statement."

The fact that you are relying on an undiscovered resource or process to suddenly and unquestionably justify a massive space industrial infrastructure is, by definition "without logical foundation". It's asserting the unkown and unkowable -- and just as likely the non-existant -- as a positive proof.

Tony said...

Brian61:

"The conceptual situation however is that we have become so used to the rapid pace of technological innovation and process improvements in certain technologies, that we've come to expect that in all technologies. That is a doomed expectation, there is only so much low hanging fruit to be plucked."

That's somewhat muddled, don't you think? We've become used to rapid progress in useful technologies precisely because useful technologies attract money to progress them. If a technology isn't useful, it's not progressed, even if it is technically capable. For example, it is an indisputable fact that the technology exists to vault people across the oceans at supersonic speed. But it's not all that useful a technology, so it's just not done anymore, and was arguably a money-losing publicity stunt even when it was being done.

In terms of space technology, rocketry progressed very quickly in capability improvement for a couple of decades. Then it became so moribund that we're still using a rocket design over 50 years old (R7) to take people into space. Bipropellant chemical rocketry was developed quickly up to the point that further improvement was marginal. Then it settled into its technological dotage, performing about as well as always, but without potential for great improvement.

If we plan to significantly lower Earth-to-orbit transport costs, we'll have to come up with something else entirely -- but nothing else that is even remotely plausible is available, even in theroy. There's just a bunch of "if we had capability X, we could do super-wonderful-awesome thing Y".

"Tony: All that said, I did not come to this venue to debate with you. Having read through a multitude of postings over the previous years of this blog, I already know that not only will you and I not agree on practically anything, but such discourse is a pointless waste of time, simply adding noise to the signal of this blog (in my opinion of course). I would much appreciate it, if you would be so kind as to ignore my posts as I will continue to do with yours, beyond this brief reply."

Let's not make it personal. I'm addressing the factual validity of ideas, no matter who offers them.

Geoffrey S H said...

Ok, now that's all said, let's just cool it and quit the questioning of authority on both sides. Its occured several times this year.

Sorry to sound... naive if you will, but the less heated the debate, frankly, the much more fun it is to read the posts.

Back on topic: It may be that micro-gravity and free-fall manufacture is useful for a currently unknown process needed by a new section of civilisation several centuries from now.
If you want space factories then I'd see that as the best way to go for now, along with the aforementioned small-scale on site manufacturing for small far-off research stations. The less relevant to our needs right now the macguffinite is, the less implausible it will immedietly seem to us.

All this eliminates the potential for PMF space battlegroups threatening far-out space factories. Thus orbital combat is electronic and information warfare carried out by satellites, with some small-scale beam combat.

Anonymous said...

Brian61:

"Many people seem to be overlooking the first form of MacGuffinite that has already been exploited, namely orbital real estate."

Which isn't used for anything remotely like what Earth real estate is.

The real MacGuffinite is communications satellites and observation satellites (whether for scientific research, weather prediction, military espionage, or whatever).


"A few bases on the moon might well make sense as it is a ready source of some raw materials in a relatively shallow gravity well, but Mars, for example, makes no mid future sense whatsoever."

I'm actually not that fond of Mars as a destination. I prefer to pass it over during the dome-building stage, then come back once the technology/infrastructure for true terraforming is developed.


"Ion drives might be entirely satisfactory in the relative near term for movement between stations and, at least for cargo, between lunar orbit and station."

Ion thrusters are more useful for building speed over the course of an extended voyage. Apollo-era tech chemical engines were able to do the Earth-to-Moon route in a matter of days, which simply isn't enough time for an ion thruster to put out a very useful amount of thrust.



Tony:

"There is no proven industrial application of microgravity, and we've been actively researching it for 30 years."

With a handful of astronauts playing with what few toys we can get them out of Earth's gravity well? For a mere 30 years? Weren't you the one who is always denying that technological progress is in a continuous accelerando?

It took all of humanity several tens of thousands of years to invent agriculture.


"While we can't absolutely rule out some magic bullet process that would actually justify the cost of space flight to implement it, there is precisely zero evidence that a space economy could be based on microgravity."

Neither confirming nor denying this, let me just note that if a larger space industry takes off for some other reason, then zero gravity manufacturing would be able to piggyback on the existing infrastructure and still produce enough stuff to be of economic worth.

Of course this requires some other reason to go into space in the first place.

Tony said...

Really back on topic...

I think a problem we have with electric propulsion is that we're waiting for something really hot (i.e. nuclear powered VASIMR) when we should just scale and power up existing technologies as much as we can. I think solar electric, based on the lightest achievable photovoltaic arrays and Hall thrusters, is something that we should be pursuing as fundamentally provent technology, with nuclear power and VASIMR (or whatever) treated as an "if and when" propsition for future development (rather than a required milestone on some roadmap).

Anonymous said...

Geoffrey S H: I'm not necessarily convinced that the 'currently unknown process' is one that must be needed by a new section of civilization. I believe it merely needs to be one which is sufficiently profitable to justify the creation of the initial infrastructure. This could be something on the relatively short term horizon. For all we know at this time, some major investors in SpaceX and Bigelow may be on an inside track, with a potential product already targeted. Now while it is undoubtedly hugely optimistic to assume that is the case, it is equally pessimistic to automatically assume that is not the case. As long as research continues, there is hope.

In fact, given that research continues and that mankind continues to progress and consume along present lines, at some point in the next century it may be that even a currently marginal process would become profitable enough to trigger investment in the infrastructure. Once the infrastructure is in place, the entry costs drop and some number of marginal process will become profitable. Processes that, in and of themselves, would not justify the expense in creating the infrastructure. There is also the possibility that some entity decides there are enough potentially profitable marginal processes to justify investment in the infrastructure as a profit making venture in and of itself.

None of this precludes the PMF scenario of warfare in space, in fact it could potentially be the cause, at the very least, would provide the historical backdrop. The trouble I personally run into is in trying to represent this in a story without explicitly naming an exact timeframe or specific MacGuffinite.

There is also question of the space travel technology that would be necessary and sufficient for such a stage in growth. This brings me back to my earlier question about whether or not the combination of an aluminum/oxygen chemical rocket with oxygen based Hall Effect thrusters would be a likely propulsion system. The particular chemicals chosen are because of their availability in the lunar regolith.

While the first factories would likely be in relatively low earth orbits, at some point it might become more economical to move/expand them to be nearer their source of raw materials. Automation of the factories would seem to be such that few, if any, personnel would be required but I find that presumption to be highly questionable. A time lag approaching that of human reflex speeds would become a limiting factor (this can be seen currently with multiplayer online games). Thus I would contend that habitation will follow industry. Eventually leading to the asteroid belt and other sources of economically accessible raw materials.

The process may well take a few centuries, but, especially as distances between point of manufacture/habitation and point of market increase, would provide the impetus for development and manufacture of better power and propulsion systems. Those would not be the only systems to see development of course, just two that are immediately relevant to the PMF warfare scenarios.

Brian61

Anonymous said...

Anonymous: "Ion thrusters are more useful for building speed over the course of an extended voyage. Apollo-era tech chemical engines were able to do the Earth-to-Moon route in a matter of days, which simply isn't enough time for an ion thruster to put out a very useful amount of thrust."

What I'm mulling over is the difference between priority traffic and slow traffic. Treating passenger traffic as priority and raw materials/supplies as (generally) slow traffic might mean that while chem thrusters are needed for manned flights, simple cargo flights might get by with Hall effect level ion thrusters.

A complicating factor is lunar gravity/escape velocity which I don't think is achievable via Hall effect, thus even the cargo carrier would need chem thruster assist for takeoff and landing.

The attractiveness of ion thrusters is that they could be largely solar powered. If I'm right about chem thrusters being required for lunar takeoff and landing, then the question becomes, do you save enough mass to justify the secondary propulsion system?

Potentially if a dual propulsion craft is viable economically, then you could simplify your infrastructure by having only one modular 'LEO-Lunar pickup truck' design used for both passenger and freight transport with varying ratios of propellant vs cargo.

On the other hand, it might be too complex and the difference between cargo and passenger service would merely be the duration of thrust of the chem fuel rockets at each end.

Would the same basic equation hold true for Lunar:L5 as it would for Lunar:LEO/GEO ?

Brian61

Tony said...

Anon:

"With a handful of astronauts playing with what few toys we can get them out of Earth's gravity well? For a mere 30 years? Weren't you the one who is always denying that technological progress is in a continuous accelerando?"

As always, space is different...except when we don't want it to be. Numerous processes have been demonstrated by experiment in space. None of them have proven quantities or qualities so much in excess of what is obtainable on Earth that space access costs are justified in industrializing them. That's just a simple fact -- whatever you do in space, it has to be so good that the market will justify totally unprecedented, orders of magnitude increases in basic logistics costs.

Of course, we are told that that is only temporary. Space access costs will come down significantly in the near future. Well, no, they won't -- not using anything like the technologies we currently have or can reasonably foresee. Lowered space access costs are a foundational myth that makes everything else people dream about space become myth too.

WRT technological progress and accelerando, what I have said is that progress in any given technology is logistic in nature (mathematically speaking), not quadratic. IOW, it can be described by S-shaped curves, not U-shaped ones. What we perceive as constant technological progress is a series of new technologies supplanting mature ones, not a single process rushing to the top. Each new technology undergoes a rapid growth phase, then levels out. If a newer technology comes along to supplant an old one, we perceive constant technological advance. But in reality it's just a series of discrete advancement phases piled on top of one another.

The problem lies in the fact that every task will eventually find its pinnacle technology. We certainly seem to have found a candidate for a pinnacle technology for space access in bipropellant chemical rockets. Nothing truly new has come along in almost fifty years. Just tweaks around the margins.

It may be -- and I hope that it is -- that a further real technological advance will come in Earth-to-orbit launch technology. But there's nothing obvious on the horizon that meets both the technical and economic test of plausibility. We appear to be stuck here for a long enough while that we should get our heads striaght about what can really be done, and give up on 1970s speculative pie in the sky.

"It took all of humanity several tens of thousands of years to invent agriculture."

No it didn't. It took a critical mass of humans in a limited area to motivate the development of agriculture as a technology. And it was developed independently in many different places around the globe, including the Americas. I doubt that in any one of these instances it took more than a few hundred years for agriculture to progress from a possibility to a widespread technical capability. And that's in oral cultures that couldn't record successes and failures for future reference.

"Neither confirming nor denying this, let me just note that if a larger space industry takes off for some other reason, then zero gravity manufacturing would be able to piggyback on the existing infrastructure and still produce enough stuff to be of economic worth.

Of course this requires some other reason to go into space in the first place."


It's much simpler and IMO more logical to just admit to ourselves that isn't going to be a big space industrial infrastructure in the PMF, possibly not for long after that. Even the development of a purely survival based industrial infrastructure on Mars is going to be contingent on humans actually being able to adapt to the conditions there, and enough resources being available to estblish them there in large enough communities.

Tony said...

There's no reason, for interplanetary transits at least, that solar electric wouldn't be used for all classes of payload. You might have slow boats that take a couple of years to get to Mars. This could either be accomplished with a standard vehicle carrying a lot of cargo, or with a reduced power/thrust vehicle carrying a standard cargo pod. For manned missions one would of course use the maximum available power an thrust. I'm thinking that the standard solution, at least for the first few decades, would be to use the maximal vehicle for both cargo and pax, but make pax a light-payload/fast-trip application, while cargo is a heavy-payload/slow-trip one.

Thucydides said...

Timeframes for ion and similar continuous thrust systems make for annoying reading. Earth to the Moon via this sort fo technology could take 90 days, but Earth-Mars flyby can be done in four months (120 days).

This suggests that Heinlein was right after all; each stage of the voyage needs its own dedicated vessel. An Ion drive (or any sort of low thrust electric drive or solar sail) does the long distance run, and drops off the high thrust/low ISP "pickup truck" to aerobrake/rocket brake and land at the target. In the case of the Earth Mars run, after dropping off the "pickup truck", the carrier loops off in a long eliptical orbit past the asteroid belt and returns to Earth about two years after launch.

If we accept most people actually want to go to Mars, a "pickup truck" designed to areobrake into Martian orbit and takeoff and land from the Martian surface would be versatile enough to be used throughout most of the Solar System so long as a suitable carrier is available.

Brian/neutrino78x said...

I don't think chemical rockets can be considered a mature technology until you have SSTO vehicles that operate like airliners, that is to say, they can go up to orbit and back down, and reuse again the same day, just refuel it.

Yes, we have been using chemical rockets for 50 years, but humans have only been going up with NASA (and equivalent agencies in other countries).

I think people need to realize that it is not going to be like that forever. NASA going to the moon was an exception to the rule, in my opinion.

Eventually, most ships in space will be private. It has to be like that if we are ever to have humans living off the Earth, which we will. It is inevitable. At first it will just be rich people having fun with their money, but eventually there will be established private colonies, self sufficient, but trading with the Earth.

Once people are going into space every day, and I mean normal, average people, not just NASA astronauts, the price to orbit will be very low.

Big devices like maglev launch assist are also inevitable. Corporations will invest their own money in such things because the large number of people in orbit will demand them. That, or the government will build them to support and/or stimulate the private industry.

I don't know how much of this, if any, will occur within my lifetime (I am 33), but the further out you go in the future, the greater the certainty that it will already have happened.

--Brian

Anonymous said...

=Milo=


By the way, the long post directed at Brian61 was me. I forgot to sign.



Brian61:

"What I'm mulling over is the difference between priority traffic and slow traffic."

Why send slow traffic when fast traffic is already "cheaply" possible with the lowest-tech engines on the block?

If you want something even cheaper, make use of the Planetary Sidewalk (my nickname) rather than moving entirely under your own power.


"A complicating factor is lunar gravity/escape velocity which I don't think is achievable via Hall effect, thus even the cargo carrier would need chem thruster assist for takeoff and landing."

Either that or you would separate shuttles which never venture beyond Lunar orbit.


"The attractiveness of ion thrusters is that they could be largely solar powered."

But they still need their propellant to be refilled. Chemical rockets are powered by their propellant. So, no advantage.

If you really want something that doesn't need to be refuelled, you need solar sails or the like.

Anyway, if supplying the fuel to your cargo vessel is such a problem, how are you supplying the cargo?



Tony:

"There's no reason, for interplanetary transits at least, that solar electric wouldn't be used for all classes of payload."

Solar power becomes less useful in the outer solar system (Jupiter is 3.415 times as far out as Mars, and so 11.66 times less sunlight). And many rocketpunk futures assume the existance of fusion plants vastly more productive than any power source we have today to justify their feasibility (again, especially for the outer system).

But yeah, I agree that ion propulsion of some sort will be the go-to method for interplanetary travel, and chemical rockets just aren't suited for that sort of application. The question is just whether to power it with solar, fission, or fusion. When you can afford to go slower because you're only transporting cargo, you would do so by simply dedicating a smaller proportion of the total ship mass to the power plant, and dedicating a larger proportion of the mass to the cargo, while keeping the same basic plant/engine design. (You could even use the same ship - at least for normal cargo and express cargo - just loaded more or less full depending on how fast you need to go. Passengers do need different ship designs due to the "cargo hold" needing to be designed for their comfort, but the propulsion will resemble express cargo ships. You can also carry small express cargo packages in a secondary section of the passenger ships.)

Inside planetary orbits, though, chemical and nuclear-thermal engines are much more useful.

Tony said...

Brian:

"I don't think chemical rockets can be considered a mature technology until you have SSTO vehicles that operate like airliners, that is to say, they can go up to orbit and back down, and reuse again the same day, just refuel it."

You've got it exactly backwards. It's precisely because chemical rockets are a mature technology that we know reusable SSTO is a physical impossibility. The most efficient long-duration rocket stage ever built, the Apollo S-IVB, without a payload or provisions for recovery, couldn't even put itself in orbit. And if it were just a matter of making the structure lighter, that would be one thing. But the stage only weighed 28,000 lb dry to begin with, while the difference between the wet weight and the engine thrust was 29,000 lb. IOW, the rocket couldn't even lift its own propellant load against the Earth's gravity, much less the propellant plus the engine, tankage, and everything else.

It's a simple matter of you can't get there from here, no matter how much you want to.

"Yes, we have been using chemical rockets for 50 years, but humans have only been going up with NASA (and equivalent agencies in other countries).

I think people need to realize that it is not going to be like that forever. NASA going to the moon was an exception to the rule, in my opinion."


I think people need to realize that it has nothing to do with NASA or any other government space agency. Physics is real and it applies constraints to the problem of space launch.

"Eventually, most ships in space will be private. It has to be like that if we are ever to have humans living off the Earth, which we will. It is inevitable. At first it will just be rich people having fun with their money, but eventually there will be established private colonies, self sufficient, but trading with the Earth."

Nothing has to be this, that, or any other way. If humans are to be in space in large numbers, it's just as likely that the Chinese will do it as a national community project as it is that the West will do it in a market-based fashion. In fact, I think it's more likely to be done by the Chinese than by us, all other things being equal. They'd take longer, but they would have a more steady hand.

"Once people are going into space every day, and I mean normal, average people, not just NASA astronauts, the price to orbit will be very low."

We're getting things backwards again. The correct statement is to say that if the price to orbit can be significantly lowered, then "normal, average people" can go to space. But since significantly lowered cost to orbit is speculative at best and implausible under most assumptions, well...

"Big devices like maglev launch assist are also inevitable. Corporations will invest their own money in such things because the large number of people in orbit will demand them. That, or the government will build them to support and/or stimulate the private industry."

Nothing is inevitable. If manned space flight is relatively low volume and the industrial base stays on Earth for the foreseeable future, then that's just how it will be. After that, who knows? It's entirely possible (especially if the Chinese take the lead, but possibly under any set of circumstances) that spaceflight is used for exploration and establishing colonies, and not much else.

"I don't know how much of this, if any, will occur within my lifetime (I am 33), but the further out you go in the future, the greater the certainty that it will already have happened."

Non sequitur -- whatever happens happens, but it doesn't follow that just because one has a preference for a given future, that future is necessarily going to happen.

Anonymous said...

=Milo=



Tony:

"It's precisely because chemical rockets are a mature technology that we know reusable SSTO is a physical impossibility. The most efficient long-duration rocket stage ever built, the Apollo S-IVB, without a payload or provisions for recovery, couldn't even put itself in orbit."

That just shows that pure chemical rockets are incapable of reusable SSTO. It says nothing about hybrid technologies like scramjet spaceplanes.

Brian/neutrino78x said...

Tony, we have, for example, the X-33/VentureStar project, which ended up getting cancelled, but I think they would have accomplished it if they had the funding. I don't see any evidence that SSTO is "physically impossible". Just have a big rocket, have large tanks of hydrogen and oxygen, some people at the top, light it up, they'll go into orbit. Yes, it is a non-trivial engineering problem, but I don't see that it is physically impossible. Just because NASA has not accomplished it does not make it impossible imo. But then, I am not a physicist.

Regardless of how many stages are used to get to LEO, we will go out and exploit space commercially. There is too much opportunity out there in space. They aren't making more land on Earth, but there is plenty on Mars and other celestial bodies.

The key thing is that, in the future, most of it will be done by private entities who don't have to beg Congress for funding. That's what makes it sustainable in the long term. I know that men will settle Mars, and I think a US Flag will be the first one planted, but I doubt it will be NASA astronauts who first land there.

--Brian

Brian/neutrino78x said...

btw tony I wonder what a Tony of 1850 would have said if I told him that one day men would walk on the Moon. Perhaps he would say it is physically impossible. ;-) It was once said that we tend to overestimate what can be done in the near term, but greatly underestimate what can be done in the far term. "implausible under any scenario" is a very broad statement, and I don't think it will stand the test of history yet to be written. I don't know if it will take 100 years or 1000 years, but I know that one day there will be as many men living on Mars and other celestial bodies as there are on the Earth currently.

In fact, go out far enough in the future, and we will have settled at various other bodies orbiting other stars throughout the Galaxy. It is just a question of how far in the future to look. But the opportunity out there is too great to ignore; it just as inevitable that we shall settle space as it was that Europe was to settle North America.

--Brian

Geoffrey S H said...

Half of me wants to agree with you Tony- space is an environment unlike any other- it is an environment larger than anything else out there. Its perfectly possible that someday all technologies will come to s development standstill due to us being unable to do anything else with them in that envronment.

On the other hand, maritime history saw ALOT of time pass before rafts were developed into larger, more seaworthy craft (Polynesians excepted). Galleys in the period from the Phonecians to Rome stayed similar in many respects (bar many improvements) before better craft, such as the Snekka and the Cog, were developed post-Rome. Yes, they were all in a planetary environment, but space is not always wholly different to that. Its this that makes me cautious about accepting your notion.

Give us a thousand years. Or Five thousand. Or a million. If we last that long, maybe we will make something better. Maybe we won't. From where we are now though, we are just pre-Polynesians speculating on whether a lateen sail can be made or not.

Tony said...

Brian (1):

"Tony, we have, for example, the X-33/VentureStar project, which ended up getting cancelled, but I think they would have accomplished it if they had the funding. I don't see any evidence that SSTO is "physically impossible". Just have a big rocket, have large tanks of hydrogen and oxygen, some people at the top, light it up, they'll go into orbit. Yes, it is a non-trivial engineering problem, but I don't see that it is physically impossible. Just because NASA has not accomplished it does not make it impossible imo. But then, I am not a physicist."

I'm going to say some harsh things, but they're not aimed at anyone in particular. They're aimed at a state of mind. There's a state of mind that believes:

That the past fifty years of astronautics has all been a bad dream,

That all of the engineers at the aerospace contractors are either too incompetent to build the spaceships of the future or too cowardly to demand that they be allowed to do so,

That the speculative engineers who like to write books know what they're talking about, while real engineers who work with rockets every day don't, and

That anybody who wants to tell you different is wrong and probably stupid.

I know this state of mind intimately because, up until about ten years ago, I embraced it wholeheartedly. My sources were SF novels, speculative nonsense in Popular Mechanics, and books by the likes of O'Neill, Stine, and Zubrin. But I found out that I was the one who was wrong, and that I was arguably stupid for accepting at face value such one-sided sources.

Fortunately for me -- and, IMO, for space enthusiasm in general -- the internet began to provide excellent free sources that tell facts to anyone who will access them. Chief among these is Mark Wade's Encyplopedia Astronautica (www.astronautix.com). It always rewards a visit, but more importantly it documents the technical history of modern rocketry in fine enough detail that what is real and what is fantasy becomes exceedingly clear.

I also started asking myself why so many reusable LV ventures never succeeded, and why it was that the Russians kept plodding along with Soyuz and Proton. I was also intrigued as to why so many space enthusiasts were so quick to discount the Russian experience with Mir, and to insist that the ISS would be different. Well, back to the internet, to Wade's site and to many others. It turns out that the Russians are the incarnation of evil for many space enthusiasts, because they never really believed in the gospel of reusability. (Yes, they built Buran, but even while they were doing it, they didn't see the engineering sense in it; they were just copying the US because they believed if the US was doing it, there must be some purpose.)

The Russians were doubly dangerous because their Soyuz had not managed to kill a crew in flight since 1971, while everybody (who was honest with himself) knew that each Shuttle mission could be the crew's last. And the Russians, with their forty year old (at the time) expendable launch vehicle, were taking tourists into space. It was just too much of an in-your-face invalidation of everything the naive American space enthusiast believed about the shape of the future.

Tony said...

Brian (2):

So why is all of this a fact? And why did the Venturestar (among many other dreamships) fail? Well, it's right there for anyone who will pay attention:

The only bipropellant mixture that even has a theoretical chance of putting a rocket in space with a single stage is the LOX/LH2 mixture. Using that mixture, it turns out that the propellant alone must take up 90% of the vehicle wet mass. That means that only 10% of the gross liftoff weight can be structure, engines, instrumentation, etc. Then, for your reusable SSTO to have any value, it has to have heat management for reentry, aerodynamic maneuvering surfaces, landing gear, and, oh yeah, enough unused mass left over for a practical payload.

The joke is this -- using real world materials, and only installing stuff that's actually needed to go up (tanks, engines, etc.), modern LOX/LH2 stages' dry wieght is at best 9% of their gross liftoff weight. And stages with that low a dry weight are upper stages, incapable of lifting their own weight against Earth gravity. The best that's ever been done with a LOX/LH2 stage that can actually lift off from the Earth is 11.8% (Delta IV first stage).

Simply put, a single, expendable stage of the most modern design can't put itself in orbit, much less itself, plus recovery equipment, plus a payload. A reusable single stage spacecraft is beyond the abilities of any technology, anywhere. It requires magitech.

Tony said...

Brian (3):

In thei nterest of full disclosure, I misled the readers a little bit. The Ariane V first stage has a very respectable 7.4% dry weight. Of course, its engine can only generate 66.5% of it's gross liftoff weight in thrust. Its optimized for medium to high altitude performance, and needs solid boosters to get it off the ground.

Brian61 said...

“I will ignore all ideas for new works on engines of war, the invention of which has reached its limits and for whose improvements I see no further hope.” --Sextus Julius Frontinus, 1st Century AD

Interestingly enough he is known for his technical articles.

Brian61

Tony said...

Brian61:

"'I will ignore all ideas for new works on engines of war, the invention of which has reached its limits and for whose improvements I see no further hope.' --Sextus Julius Frontinus, 1st Century AD

Interestingly enough he is known for his technical articles."


Specious argument. I'm addressing bipropellant chemical rockets specifically, WRT assertions of capability for reusable SSTO. It's a mature technology and we know that it can't be done with that technology, because the technology won't even support expendable SSTO operations with any kind of usable payload.

Now, if you want to talk about as yet uninvented alternative technologies, or as yet fiscally non-viable megastructural/megasystemic technologies. There may be a technological capability there. But of course the megatechs are not reusable SSTO, while uninvented technologies are just that -- uninvented (and imaginary).

Brian61 said...

Wasn't making an argument, merely presenting a fact.

For PMF scenarios however, I would agree that SSTO chemical rockets are not in the picture. At least not as the sole propulsion mechanism. It does bring up the rather pedantic question of whether or not solid rocket takeoff assist packs for a ramjet style SSTO doesn't disqualify the single stage categorization.

In the long run, advances in materials technologies, currently unfeasible (or perhaps even unknown) exotic fuels, and the choice of a launch site 1.5km closer to orbit than the Cape, might mean a chemical rocket SSTO could be done as a stunt. A stunt because it doesn't seem to make much economic sense.

For any near term SSTO concept I question the optimistic turn around times since using any substantial amount of aerobraking on reentry is going to erode materials and introduce some amount of thermal shock. In my opinion SSTO is really only a requirement for tourism and perhaps gerontologic medicine, other fields of endeavor having possible commercial viability don't require it.

Brian61

Tony said...

Brian61:

"Wasn't making an argument, merely presenting a fact."

I would respectfully advise you not to try to get too cute -- plain facts are not the same thing as factoids used to manifest rhetorical tricks.

"It does bring up the rather pedantic question of whether or not solid rocket takeoff assist packs for a ramjet style SSTO doesn't disqualify the single stage categorization."

See, now we've got our thinking caps on. Solid boosters for any kind of notionally reusable spacecraft would make it "stage and a half", provided the craft's main propuslion engine was running at launch. If it wasn't in operation, then the spacecraft would be a second stage in a two stage arrangement.

In any case, one has to evaluate a reusability scheme against it's actual cost, not its philosophical bona fides (reusability being a religion in most cases, not a validated engineering requirement). So what are we actually trying to reuse? Engines, tankage, avionics, perhaps crew accomodations? Doesthe value of reusing those actually exceed the cost of what you have to do to reuse them? What are those costs? For a given system size, it usually works out to reduced payload (to the point that the Shuttle puts 120 tons in orbit, but only leaves 20 of those tons there), added complexity (which has to be compensated for by either the acceptance of reduced reliability or more expensive engineering qualifications), and extra time to do everything.

It turns out that you just can't run rockets like airliners. Rockets, unlike airliners, experience so many different dynamic regimes in flight that they're either highly optimized (through the mechanism of staging) to take them in manageable slices, or they're over complex and ridiculously costly in ways that airliners just don't have to be.

Brian61 said...

Milo: "Why send slow traffic when fast traffic is already "cheaply" possible with the lowest-tech engines on the block?"

(Also referring to but not re-posting the remainder of the reply.)

Cheap is a relative concept.

I'm examining transportation in the limited scope of LEO to lunar surface (also looking at future use of Lagrange points) for a plausible near future scenario. Specifically as it plays a role in a postulated economic setting composed to a large degree of micro-g manufacturing facilities (stations) with as much of the raw materials requirement as possible coming from the moon rather than Earth.

In this scenario there are two general categories of transportation required, one is that of people and critical time dependent supplies, the other is the movement of raw materials. Terrestrial equivalents would be looking at solutions involving the airplane and the freight truck (or possibly pipeline) to solve similar problems.

Speed affects the cost of shipping and there is an interest cost on the investment the raw materials in transit represent. Basically we are comparing the cost of shipping to the interest on the value of the cargo in transit over time. In the plausible near future setting, economic planners would merely solve the simultaneous equations involved. Note that there might be other possible economic limits to pipeline depth since anything in the pipeline has already incurred a cost, reducing available funds.

I was originally thinking that ion tugs might make sense as part of the pipeline, presumably they would be cheaper, less dangerous, and frankly more possible than catapults. Trouble is in the area of space under inspection, the distances are too short for ion engines to really come into their own.

Furthermore, in examining the situation you have to consider that perhaps the chemical rocket propulsion equipped vehicles, required for the fast travel traffic, could be used for raw material transport (at a different fuel/payload ratio) more cheaply than ion tugs. Due to the fact that ion tugs would require a certain amount of duplication of transport infrastructure and that you would still need chemical rockets or some other system to get payloads into lunar orbit from the surface, the case for ion propelled tugs in this setting looks less and less viable.

As a side note, I think part of the reason some of us talk past one another so easily is that we have widely different interpretations of the word plausible.

Brian61

Tony said...

Brian61:

"As a side note, I think part of the reason some of us talk past one another so easily is that we have widely different interpretations of the word plausible."

That's hitting the nail on the head. You appear to be trying to work out the microeconomics of a regime that I estimate to be macroeconomically implausible.

Brian61 said...

Tony: "You appear to be trying to work out the microeconomics of a regime that I estimate to be macroeconomically implausible."

Thing is, I don't see any other plausible route to a permanent presence in space. I know, people would like tourism and colonization of planets, unfortunately both of those require that practically the same infrastructure be built as for manufacturing with far lower economic returns.

Adding to that, the scenarios pushing for colonization that rely upon historical roots run into a huge problem. Colonization of Mars as a solution to overpopulation of Earth would, at this moment in time, require the ability to relocate three people per second in order to just stay at the same population level!

As for dissident groups like the Pilgrims immigrating for political reasons.. need some mighty rich Pilgrims. Any scenario where governments might negotiate with a dissident group offering to pay a substantial portion of the cost fails since the popular outcry in democracies would shoot it down and totalitarian governments would, if they found a dissident group naive to trust them, simply eliminate or imprison them instead.

Immigration for economic opportunity reasons fails in any case where NEO manufacturing would fail especially since those most motivated to relocate would be those least able to afford it and there is little, if any, benefit to anyone else in assisting them.

There is, of course, what is to me the single overriding best reason to establish a permanent presence in space of sufficient size to form a viable genetic pool: eliminate the current "all the eggs in the same basket" risk the human race currently endures. Unfortunately we, as a race, are too blindly short sighted for that to be anywhere near a sufficiently motivating factor.

It is pretty simple to me, either economic forces lead the way into space in the near future, or we wait a very long time until it is cheap enough for tourism alone to bear the costs.

Brian61

Anonymous said...

=Milo=



Brian61:

"There is, of course, what is to me the single overriding best reason to establish a permanent presence in space of sufficient size to form a viable genetic pool: eliminate the current "all the eggs in the same basket" risk the human race currently endures. Unfortunately we, as a race, are too blindly short sighted for that to be anywhere near a sufficiently motivating factor."

That's exactly it. We're shortsighted. We mostly care about things that are going to happen in the near future.

While a natural disaster big enough to threaten human survival might occur, such events happen extremely infrequently. (A commonly cited example in these discussions is the extinction of the dinosaurs. Well, that happened 65000000 years ago, remember?) I predict an extremely slim chance of any kind of civilization-threatening natural disaster taking place anytime in the next few thousand years, and a still pretty low chance of it happening anytime in the next few million years. Those are both well beyond the plausible midfuture, and are plenty of time for us to figure out the necessary tech to avoid it at our leisure. There is, simply put, no rush. We simply aren't ready to worry about these things anytime soon, nor do we need to.

The one kind of disaster that might theoretically happen in the nearer future would be a human-made disaster, such as a nuclear war or extreme environment damage. Even accounting for the fact that those things aren't as likely as many people make them out to be, they can be more efficiently solved by turning inwards and just making sure we don't do those things (by promoting peacefulness, environmental awareness, etc.). If you're so worried about human malice and stupidity ruining things, then frankly sending the humans to the stars won't help much - since they'll still be malicious and stupid there too, and probably more so due to the extreme scarcity of resources like food and air.

Brian61 said...

Milo: "While a natural disaster big enough to threaten human survival might occur, such events happen extremely infrequently."

Funny thing about probabilities, they're great tools for deriving reliable numbers given large sample sizes, on the other hand, they say very little about a sample size of one. I'm sure more than one first time flier has been aboard a fatal flight.

I'm well aware that the odds are given as one in a billion chance for each known extinction level event, trouble is it could happen tomorrow as easily as next week, next year, next century, next millennium, or never. Then there are the possible unknowns, theoretical events, the 'oops we really shouldn't have broadcast our existence' events (The Killing Star - Pellegrino/Zebrowski), non-extinction level but civilization destroying events after we have exhausted and dispersed the stepping stones (copper/iron/oil/etc), and likely a number of possibilities I've never heard of.

The only thing we really know about extinction level events is that they can happen.

"There is, simply put, no rush. We simply aren't ready to worry about these things anytime soon, nor do we need to."

That is the logic of extinction. Each day we possess the capability to mitigate the possibilities and instead do nothing, we are playing Russian Roulette with the survival of the human race.

"If you're so worried about..."

I don't spend my time worrying about it, for one it is entirely beyond my control, only thing I can do is once in awhile trot it out in public... not too often of course, I'm allergic to padded cells.

Brian61

Tony said...

Brian61:

"Thing is, I don't see any other plausible route to a permanent presence in space."

The problem is that your route is manifestly not plausible. Why would anybody invest in building an industrial infrastructure in space when one exists on the ground? If you argue that we need it as a hedge against diminishing resources on Earth, you get the the same answer as with colonization for species survival insurance: "It's not my problem, right now." If you say well, it will become more competitive as Earth resources become more expensive, you would be mistaken. As Earth resources become more expensive, so does space flight. It never become relatively less expensive.

"It is pretty simple to me, either economic forces lead the way into space in the near future, or we wait a very long time until it is cheap enough for tourism alone to bear the costs."

This statement is semantically null. Tourism is a subset of economic forces. So your statement works out to: if all economic forces fail, we'll have to wait a long time until a particular one doesn't. Huh?

WRT the species distribution argument, look...all species eventually become extinct. What makes us special? The more logical, though less altruistic argument is that successful species expand their ranges. That does provide insurance against local disasters, but it also expands the resource pool available to persist the genome. This suggests that if we're a truly successful species, we'll naturally expand into space if we can. If we can't, it's either because we're not fit enough for that stage of epxansion or because it's impossible. In either case, making philosophical arguments isn't going to make a difference in the long run.

Citizen Joe said...

The storylines you guys are looking for when it comes to low thrust drives is Gilligan's Island. They used a high thrust vehicle to get to their transportation habitat (the island) whereupon they are stuck, minus some radio communication, until they reach their destination (get rescued).

Thucydides said...

Ion drive and other constant acceleration drives might not have great pickup, but can reach pretty spectacular velocity if you wait long enough. Think again about the example of using a low thrust/high ISP drive:

Earth-Moon=90 days
Earth Mars=120 days (flypast)

Making this work requires some understanding of orbital mechanics and long term planning (your constant acceleration carrier ship drops sub vessels off at Mars to aerobrake, and takes a long looping orbit to return to Earth about 2 years after launch).

WRT cargo vs people; people are high priority cargo and should get there as fast as possivble to minimize unproductive "down time", life support needs and radiation exposure. Most cargo (especially bulk material and consumables) can be sent most economically via minimum energy orbits, and I don't see the need for a ship; the space age version of an ISO container shot out of a mass driver will do. The critical driver in space is delta V, not absolute speed. The less delta V you use, the less energy you expend which is the lowest cost option for space travel.

Dissident groups heading for space will indeed need to be wealthy, but then again, the Pilgrims were wealthy in relative terms compared to most of their neighbours in the 1500's. A philosophy defined by hard work, thrift and internal trade (amongst others of the "elect") built and concentrated wealth. The Hugenots were in a similar situation, but since most of their "wealth" was their skilled tradespeople, it was efficient and possible for English nobles and trade guilds to sponsor their passage from France in the expectation of reaping great profits from the use of this skilled labour. There won't be much of an analogy in space, but we already see a modern version with Universities and research labs importing highly skilled students and researchers from India and China.

Tony said...

Thucydides:

"Making this work requires some understanding of orbital mechanics and long term planning (your constant acceleration carrier ship drops sub vessels off at Mars to aerobrake, and takes a long looping orbit to return to Earth about 2 years after launch)."

That's certainly one way of utilizing ion propulsion, but it's not the only way. One might, for example, accept relatively long 6-7 month transits, in exchange for the larger payload fraction that high Isp propulsion allows. Or one might accept longer transits in order to keep the ship with the mission as a return capability.

"Most cargo (especially bulk material and consumables) can be sent most economically via minimum energy orbits, and I don't see the need for a ship; the space age version of an ISO container shot out of a mass driver will do.

The ship is a modular, self-contained capability. A mass driver imposes a minimum investment and a more complex in-space infrastructure. You want to use ships for the same reason guerillas love rocket artillery: any single rocket is a usable round of ammunition in and of itself. You can take it out and fire it with minimal (if any) support equipment. But to fire even a single artillery shell, you have to have the whole gun, up front. By the same token, a ship is a capability you can use right now, without any extra support. Mass driver launched containers first need the mass driver, which is a huge investment.

Brian61 said...

The lower the value of a cargo, the more amenable the economics are to sending that cargo via a slow route. It still begs the question of "How slow?".

Leaving out the actual mechanics of launch and recovery of 'cargo packets', the transit time inflates their effective cost. A simple way of looking at it is that if a cargo has a value of x, then the transit time inflates x by the interest accrued on x over the transit time.

Infrastructure costs are capital costs amortized over the useful lifespan *and* subject to a maximum cost by what percentage of available funds can be allocated to them. The cargo value x is inflated by a percentage of the amortized cost.

Although it is tempting to consider it as 'simple economics' it is actually anything but simple. Any costs projected into the future are subject to varying degrees of error which must be accounted for in the analysis.

Cutting edge infrastructures may very well run into cost overruns as the initial projections almost invariably turn out to be flawed and overly optimistic. An infrastructure based on mature proven technologies is more likely to be chosen unless the benefits in the cutting edge infrastructure are very large in the cost vs risk analysis. It is also important to realize that the more costly and central to the enterprise an infrastructure subsystem is, the more likely a conservative cost vs risk analysis will be used.

Even assuming that the risks are acceptable, the costs are relatively low, and the inflation of cargo value over the transit time is acceptable, there is one last hurdle to overcome. The start up time of the pipeline must fall within an acceptable time frame. That, in turn, depends upon the time frames that the commercial entity and its investors are accustomed to working with.

(continued next post)-Brian61

Brian61 said...

(continued from previous post)
All of this makes the mass driver minimal energy course pipeline unattractive for the frontrunners in the commercial exploitation of NEO manufacturing. Even if your process is amenable to cargoes of raw regolith, yielding cargoes of the minimum possible value, the transit time plus the development and deployment time of the mass driver minimal energy course pipeline is going to inflate the cargo values to unacceptable levels.

To make it work, you would need to build your lunar side infrastructure years before the manufacturing facility. Also consider the political ramifications, you're launching unguided projectiles in a path very close to earth intersection. If the venture that started the enterprise goes broke before completing the 'catcher' side of the mass driver pipeline and you have a fairly full pipeline - someone has one heck of a mess to clean up.

Consider the mess we currently have surrounding nuclear power. Most people don't care that it is possible to build safe reactors that don't generate tons of nuclear waste, the paranoia due to disasters in the industry far outweigh the education level. One unguided cargo that precipitates an accident resulting in casualties (or even has the potential to cause casualties) here on Earth will basically shutdown any such pipelines for a very long time.

Mass driver pipelines and minimal energy courses may indeed have their place in the future, but I would argue that they would find their use in mature settings as an optimization rather than in any earlier setting.

Ion drive cargo tug pipelines are a bit more attractive. Anything beyond the NEO environment would likely use something along those lines. In the NEO environment though, I've come to the conclusion that it can be done more cost effectively using aluminum/oxygen chemical rockets.

With the rockets, you could conceivably use the same basic components for both high priority and low priority traffic. In the low priority case, the rocket pipeline wouldn't need all that much propellant mass yielding favorable payload mass ratios. The vehicles themselves would be pretty cheap, likely a modular design would be chosen such that both traffic models used the same basic engines, structure, and guidance packages. Both production costs and maintenance costs would be lower and reliability would increase.

Brian61

Citizen Joe said...

Non degrading fungible commodities could be sent on the slow route. It doesn't matter if it takes 20 years for a specific crate of rocks to get from A to B, only the amount of rocks per week that arrive. The moment you stick that crate of rocks on a ship, you've added a degrading asset to the equation (the ship).

However, the push towards drive trains will likely come from a space law issue instead. First, there is the issue of accidentally crashing said crate of rocks, so everything needs to have its own propulsion before being cleared for flight. Second (and this could stem from the first) is that things not under their own power could be considered adrift and a navigation hazard, thus allowing anyone to take the crate as salvage.

Brian61 said...

Citizen Joe: "The moment you stick that crate of rocks on a ship, you've added a degrading asset to the equation (the ship)."

You're leaving out the cost of the work that creates the crate of rocks. That cost is a 'lost opportunities' cost, in other words, an investment. If a crate of rocks costs $1.00 to create, then 20 years later, at say 3% interest compounded yearly, it arrives with a cost of roughly $1.80.

Part of the cost of the crate of rocks is the associated operational cost, another is a percentage of the amortized cost of the infrastructure necessary for its creation. No commodity has a zero cost.

During the startup phase of the enterprise though you need to consider the investment represented by the pipeline itself - you have to pay the cost of everything in the pipeline before you can use the first delivery.

Good catch on the salvage law part, I'd completely overlooked that consideration.

Brian61

Rick said...

Pedantic quibble that while all electric drives involve ions, and the popular culture trope uses 'ion drive' as synonymous with electric drives in general, I'm pretty sure that the technical meaning of ion propulsion specifically applies to drives that project an ion beam, and does not include (for example) magnetohydrodynamic drives.

On the broader discussion, while I have obviously fallen behind on posting, I have not disappeared, and will likely take this issue up next post.

Long time regulars here know that I by no means think that the classic vision of the space future is inevitable in the PMF, or necessary, or for that matter very likely - though I would hesitate to rule it out entirely.

But I will take all this up in a front page post!

Brian/neutrino78x said...

Tony wrote:
The best that's ever been done with a LOX/LH2 stage that can actually lift off from the Earth is 11.8% (Delta IV first stage).

Simply put, a single, expendable stage of the most modern design can't put itself in orbit, much less itself, plus recovery equipment, plus a payload. A reusable single stage spacecraft is beyond the abilities of any technology, anywhere. It requires magitech.


Your conclusion does not follow from your syllogism.

All this tells us is that, given present technology, an SSTO cannot be done.

Yes, I know about mass ratios etc.

Again, all you need is a large tank of hydrogen, large tank of oxygen, some people at the top, and a rocket engine to light it up, and you can get to orbit.

By your logic, one could say, in 1950, that a handheld computer with the power of the iPhone is "physically impossible", since, at the time, the smallest computer weighed over a metric tonne! :-O

Certainly, Admiral Rickover had to campaign aggressively to get the Navy to attempt to design a nuclear submarine, because many people were telling him that is "physically impossible" to build such a small nuclear reactor. They were wrong. Same thing with ships made of metal (people used to say "metal doesn't swim!"), heavier than air flight, breaking the sound barrier, etc.

You haven't presented any evidence that the laws of physics, per se, prevent an SSTO rocket from being built, merely that it is has never been accomplished so far. As I said, it is certainly a difficult engineering project, but imo it is "difficult" rather than "impossible".

From what I can ascertain, "Technical problems with the X-33's composite liquid hydrogen tank resulted in the cancellation of the program in February 2001." So, does that sound like it was "physically impossible"??? It is from here:

http://www.dfrc.nasa.gov/gallery/photo/X-33/HTML/EC96-43631-2.html

--Brian/neutrino78x

Brian/neutrino78x said...

btw tony, a nuclear SSTO would be a single stage fully reusable spacecraft, I don't think anyone disputes that a nuclear rocket could accomplish SSTO.

But I didn't bring that up before because we were concentrating on H2/O2.

Regardless, whichever technology is used, I think it is inevitable that we will colonize space, and have people going into space every day. I don't know how long it will take, I just know it will eventually happen.

I think Silicon Valley, where I'm from, is driving a lot of that. Prior to the microcomputer revolution, most billionaires were stodgy old men who had no interest in space and didn't grow up on Star Trek/Star Wars.

Now you have people like Paul Allen, who has a lot of money, and is a nerd, and grew up on Star Trek. Hence, he funded an X Prize team. Yes I know MS is not a SV company, but you wouldn't have MS millionaires without SV.

--Brian/neutrino78x

Tony said...

Brian/neutrino78x (1):

"Your conclusion does not follow from your syllogism.

All this tells us is that, given present technology, an SSTO cannot be done."


That's exactly the point I'm trying to make. But what you seem to be refusing to understand is that "present technology" is mature, and it's the only technology we have. Bipropellant chemical rockets have real physical limits that can't be handwaved away.

"Yes, I know about mass ratios etc.

Again, all you need is a large tank of hydrogen, large tank of oxygen, some people at the top, and a rocket engine to light it up, and you can get to orbit."


Knowing about mass ratios and understanding what they mean in engineering terms are two entirely different things. You can't just put together enough propellants, an engine, and people and put the whole schmeer in orbit. Even without any payload, an engine light enough to bring in the assembly at less than 10% dry weight isn't powerful enough to get the stage off of the ground. And an engine with enough thrust to do it makes the stage too heavy and/or burns out before achieving orbital velocity. Add a useful payload and it just amkes the above calculus less palatable to SSTO hopes.

That's the shape of real engineering constraints on expendable rockets. Recoverable SSTO rockets, with everything one needs to effect recovery, are even further from reality.

"By your logic, one could say, in 1950, that a handheld computer with the power of the iPhone is "physically impossible", since, at the time, the smallest computer weighed over a metric tonne! :-O"

Miniaturization was enabled by the invention of the transistor, which was already accomplished by 1950. That's where your analogy falls down -- nothing has been invented that could replace the cehmical rocket in launch vehicle applications. When something is invented, we can have a different discussion. But until then you're drawing to an ace and a five, asserting that the deuce, trey, and four will turn up, simply because if they don't, you can't make your hand.

"You haven't presented any evidence that the laws of physics, per se, prevent an SSTO rocket from being built, merely that it is has never been accomplished so far. As I said, it is certainly a difficult engineering project, but imo it is "difficult" rather than 'impossible'."

Yes -- it is impossible in engineering terms, because the ends can't be stretched to meet, with the materials we have available. It's certainly theoretically possible, if you can invoke materials to make all of the non-payload structure and equipment light enough. But when you do so, you're invoking non-physical, imaginary materials. Rocket engineers work strictly in reality, and they can't invoke unobtainium.

Tony said...

Brian/neutrino78x (2):

"From what I can ascertain, 'Technical problems with the X-33's composite liquid hydrogen tank resulted in the cancellation of the program in February 2001.' So, does that sound like it was 'physically impossible'???"

You'll have to take my word for this, since I don't think he ever wrote it down on his blog, but 'long about the time that X-33 was cancelled, Jerry Pournelle was telling anybody that would listent that the whole idea was running into so much reality that it simply wasn't going to be able to cope. Among the things he mentioned in my hearing were:

They had underestimated the weight of structure required to deal with dynamic stresses in two axes (the vertical launch axis and the horizontal reentry and landing axis).

The tankage was too heavy, no matter what material it was made out of.

The propulsion assembly was so heavy that the airframe wouldn't fly without placing several tons of ballast in the nose. This ballast basically eliminated any payload margin that might have existed.

The tank test failure may have been correlated closely in time with project cancellation, but it wasn't the real cause. The real cause was that they were trying to do something that couldn't be done.

Tony said...

Brian/neutrino78x (3):

"btw tony, a nuclear SSTO would be a single stage fully reusable spacecraft, I don't think anyone disputes that a nuclear rocket could accomplish SSTO.

But I didn't bring that up before because we were concentrating on H2/O2."


I'll dispute it, and on engineering grounds. One of the engineering requirements for nuclear rockets run in or near the earth's econsystem is that they are absolutely 100% reliable WRT radiological safety. Since that's an engineering impossibility, nuclear SSTO is an engineering impossibility.

Now, I know without being told that you think that's an invalid requirement, because it has a high political component that you think can be ignored. Sorry, but you would be wrong. There are many engineering requirements that have political or commercial bases that have to be and are met. Among them are CAFE (with a little bit of fudging, but still consciously addressed in motor vehicle design), steam boiler safety, electrical equipment safety, etc. Radiological safety is a real requirement, and the way the politcal landscape now stands it is a political impossibility that the people will value space access above ensuring it.

"Regardless, whichever technology is used, I think it is inevitable that we will colonize space, and have people going into space every day. I don't know how long it will take, I just know it will eventually happen."

Nothing in human affairs is inevitable. Asseting that something is inevitable is a denial of reality. It would be nice IMO if the human race could access and eventually populate space. But asserting it will happen is simply shutting out lessons we are learning about how expensive and dangerous it is and may remain to be.

"I think Silicon Valley, where I'm from, is driving a lot of that. Prior to the microcomputer revolution, most billionaires were stodgy old men who had no interest in space and didn't grow up on Star Trek/Star Wars.

Now you have people like Paul Allen, who has a lot of money, and is a nerd, and grew up on Star Trek. Hence, he funded an X Prize team. Yes I know MS is not a SV company, but you wouldn't have MS millionaires without SV."


Paul Allen is twelve years older than I am. He didn't grow up on Star Trek. He was 13 years old by the time the show was introduced. Now I grew up on Star Trek. It was already in syndication by the time I was old enough to watch TV regularly, but I can remember coming home from school and watching it every night.

Yet somehow that didn't prevent me from finding out and accepting the facts. And the Silicon Valley people who get involved in space enthusiasm, and who actually put their money into space ventures, they learn the facts soon enough.

Tony said...

For those of you that think it's all NASA's fault, and Apollo is the prototypical example of what went wrong, I offer for your consideration a transcript of a 1962 meeting between several NASA administrators, including their chief, James Webb, and several Administration officials, including President Kennedy:

http://history.nasa.gov/JFK-Webbconv/pages/transcript.pdf

What becomes most apparent upon reading this transcript is that from the very beginning NASA had a good understanding of who the real customers for space technology were: DoD, scientists, weather experts, and communications providers. The President, on the other hand, was solely focussed on the national prestige value of putting men on the Moon. He didn't even really care about space otherwise. Yeah, blame NASA, they don't have a clue...

Jim Baerg said...

Re: Space salvage laws & unpowered cargo pods in the 'pipeline'.

The salvage laws *might* be written so that anyone can pick up the cargo pod & claim salvage, but it depends on who has the most influence in the legislatures.

For many years the Ottawa River was used to transport logs from where-ever the tree was cut down to the sawmill or pulpmill. Individual logs would often get loose & drift to water shallow enough for the log to get stuck.

My understanding of the law when my parents had a cottage on the Ottawa river was that only the company whose mark was on the log was allowed to take the log.

Elsewhere eg: British Columbia the law IINM is that people who salvage logs *have* to bring them to the company that marked the log to get paid.

By analogy with log transportation on rivers & the coastal waters of BC I could see the rules in space go in many ways.

Thucydides said...

Nuclear powered SSTO without recovery *may* have been the driving force behind an SDIO program code named "Timberwind", which from the unclassified clues released in the 90's seems to have been a modernized NERVA with 20 years of materials science and engineering applied to a project that started in the '50's and ended in the early 60's.

Even the weight of the Administration, DoD and the SDIO behind it didn't make this project paletable enough to come out of the black and into production; so far as I know Timberwind didn't even make it beyond some hardware mockups and engineering validation studies (putting components in thermal test furnaces and so on).

How much more compelling would a project have to be before it was approved as a hardware item ?[/rhetoric]

So even though modern NERVA engines most certainly have the theoretical capacity to provide power/weight ratios greater than unity and high enough ISP to make a SSTO with a remass fraction well under 90%, we can eliminate that as a practical possibility.

The best possible route may be to follow Liek Myrabo's "Lightship" path. Since it is theoretically possible to build lightships containing "nanosatellites" and launch them with relatively small lasers, you don't have that much of an infrastructure bill compared to large rocket launch facilities. Nanosats can be useful, the University of British Columbia created a satellite called "MOST" which is a mini space telescope about the size and shape of a barracks box http://www.asc-csa.gc.ca/eng/satellites/most/news_100609.asp

As the need for bigger satellites or more launch capability is desired, more lasers can be added to the site in a modular fashion and multiple lasers ganged together to power bigger capsules into orbit. This avoids the massive infrastructure bill and amortizes the costs over long periods of time.

Tony said...

Thucydides:

"The best possible route may be to follow Liek Myrabo's "Lightship" path."

The problem with laser launch is that you have to commit to a whole system capable of launching an arbitrary number of payloads of a given wieght before you can actually launch a single payload of that weight. It's the same story with elevators, Lofstrom loops, fountains...whatever.

Citizen Joe said...

RE: Space Salvage
I've worked on settings where 'claiming' an object in space required 1) a transponder, 2) impart a predictable orbit, 3) file flight plan with a space authority. Do all that and you have the right to defend it, but you also are responsible for correcting any orbital problems. If you don't fix said problems, the space authority can and will send either salvagers or send a military vessel to destroy it... and then fine you...

Re: Lightships
pretty much any launch system hinges on the notion of having a reason to be in space. That reason will dictate the launch protocols and requirements. So it won't be arbitrary.

Tony said...

Citizen Joe:

"pretty much any launch system hinges on the notion of having a reason to be in space. That reason will dictate the launch protocols and requirements. So it won't be arbitrary."

"Arbitrary", when talking about numbers in technical discussions means "not inherrently limited". To launch any given weight of payload with a megastructural launch system, you must first build the entire system capable of launching that weight a technologically unlimited (i.e. arbitrary) number of times. With rockets you build one rocket per payload and only enough pads to meet your launch rate. It is perhaps more costly per payload, but the overall system is less expensive in meeting the market's capacity requirements.

Anonymous said...

=Milo=



We do need an arbitrary number of space launches. We have reasons to launch both scientific and commercial payloads, and we will probably continue to have cause to launch those for a long time. The question is whether megastructures will recoup their costs before technology advances to the point those megastructures are obsolete, or before the megastructure breaks down from old age.

Brian/neutrino78x said...

Tony, I don't blame NASA per se, I just think that, historically, the government does not provide sustainable commerce. NASA is not good at doing routine things cheaply, quickly, and reliably; that is the domain of commercial enterprise.

It should no more be the role of NASA to launch people into LEO than it is the role of the FAA to send people from New York to London. Private enterprises transport people across the Atlantic; the FAA has just an advisory and regulatory role.

Anyway, just because only 1% of your vehicle can be cargo does not make SSTO "impossible". It just means it has to be a large vehicle, so the 1% is reasonably large. You can take the Space Shuttle external tank, put Space Shuttle Main Engines on it, and it will go to orbit. No laws of physics are violated. People used to say it was "physically impossible" to fit a nuclear reactor on a submarine and do it safely, but they were wrong.

See http://www.spacefuture.com/vehicles/building.shtml

Just because the engineering is non-trivial does not mean it is impossible to do. Maybe impossible for the NASA of 2011. I bet the NASA of 1969 could have done SSTO, and would have, were it relevant to what they were doing.

--Brian

Thucydides said...

Tony

While you are correct in stating "commit to a whole system capable of launching an arbitrary number of payloads of a given wieght before you can actually launch a single payload of that weight.", the beauty of the Lightcraft system is the requirements are so small that you don't have to start with a massive investment in infrastructure.

The MOST satellite weighed no more than 30kg, so if your launch system only needs to boost that amount into orbit, then you have a reasonable starting point. Of course, the lightcraft structure itself, and a small rocket to circularize the orbit is needed, but the launch laser might only need to provide the energy to lift 100kg, which is still a reasonable and realistic proposition.

If and when you progress to the point of needing lots of launches, or want to sell the ability to loft 200kg into orbit, you add more modules to the system, upgrade the mirror and so on. Every increase in capability is inceimental, and does not need to be added if the demand is not there (unlike elevators or launch loops, which don't work at all until they are completed.)

Lightcraft are modular, scalable and don't inolve the use of magitech, so seem to be the only real alternative to conventional rocketry to get to orbit. Interestingly, this is probably the only system that also works well in space, so long as there is a source of remass and a laser emitter capable of tracking the power target. Medium to high thrust and relatively high ISP make this something worth considering.

Thom said...

Back to the original discussion, I never see ion drives or electrical drives of any sort ever being used on any form of spacecraft with a mass of more than 100 tonnes at the ABSOLUTELY MOST MASSIVE. The problem is heat dissipation. Lets look at a hypothetical spacecraft from 2250-What i consider to be the upper end of the plausible midfuture. It has a mass ratio of 2, and is 750 tonnes empty for an average mass of one thousand tonnes. We will assume an exhaust velocity of 200,000 meters per second, and a thrust of ten thousand newtons, giving our ship an average acceleration of about one milligee. Ten thousand Newtons coming from 200,000 meter per second exhaust necessitates a mass flow of one twentieth of a kilogram per second. Using the kinematic formula of K(e)=1/2mv^2, thrust power is one gigawatt. Now assuming a (generous) effeciency of 50 % for both power generation AND thrust generation, thermal waste is about three gigawatts, and total power generation is 4 gigawatts. To produce four gigawatts of power even with fusion technology of 2250 (I imagine it to be deuterium tritium fusion due to the rarity of helium-3 and the difficulty of other possible methods) would require not only a reactor but a massive steam plant, likely with more than the 750 tons of mass allotted for the ship. Dumping the waste heat would require a massive radiator, which when combined with the power system is certainly larger than 750 tonnes. Increasing specific impulse or mass of the ship only makes these problems more apparent. So my point is this: Unless you go with relatively small ships, or you handwave some magitech drive, no electric drives for you.

And for those of you who will counter this with arguments of solar or beamed power, remember: solar panels would lose most of their usefulness at about the orbit of mars and would likely be even more massive than thenuclear reactor, barring some magitech panels. And a note about beamed power: it has been proven many times on this blog that the idea of a beamed weapon capable of reaching across sizeable fractions of an AU is pure magitech. Beamed power is very little more than a watered down beam weapon. Why should it not suffer from the same problems? Unless you use a gamma ray laser or some other nearly as high frequency beam. But there are parts of me that find the idea of bathing your ship that's full of warm fleshy bodies in a bath of gamma radiation to be a bad idea.

Thom

Scott said...

I dunno, Rick. I think applying a spaceship-sized ion drive to California would really help reduce the traffic problems!

My problem with electric propulsion is the mass of the power source. I've seen a 2-seater electric car (basically a 4-wheeled motorcycle) that weighs about 2000lbs. Sure, it gets up and scoots, but the mass of the battery pack is killing range and efficiency.

Spacecraft have the same problem. Nuke plants (fission or fusion) are innately heavy. Fission plants have high-mass fuel and high-mass support systems (generators and shielding), while any proposed fusion plant has *very* high-mass support systems (between the electromagnets and lasers needed for ignition) and still needs shielding, too. Solar requires panel areas measured in square kilometers to have enough juice to run any drive with thrusts measured in things greater than microgees.

Anonymous said...

From what Scott said, maybe something like a fission-fragment drive or some sort of hybrid drive might be reasonable for interplanetary spacecraft of the 22nd and 23th centuries. It would seem that the one of the most importaint considerations for designing a space drive in the future will be for it to be compact and with a high power-to-mass ratio. Something to think about.

Ferrell

Brian61 said...

Thom: You might want to take a look at vapor core reactor designs using MHD generators and UF4 fuel. While fuel efficiency is lower, efficiency per ton is much higher as secondary heat exchangers are eliminated and the entire system operates at a much higher temperature where the radiators are far more efficient.

How practical those designs turn out to be is another question.

Another mass reducing strategy for an electric drive non-warship is a modified Valkyrie space craft design where instead of using a tow motor, you would tow the reactor. This greatly reduces the required mass for shielding and reduces overall structural mass. Alternatively, you could simply use the tow-motor design, or even distribute the ion drives between the payload and tow motor.

Such a design wouldn't look anything like popular conceptions though and would be very unsuitable for any rapid maneuvering.

Brian61

Tony said...

Brian/neutrino78x (1):

Tony, I don't blame NASA per se, I just think that, historically, the government does not provide sustainable commerce. NASA is not good at doing routine things cheaply, quickly, and reliably; that is the domain of commercial enterprise.

There's an old and fundamental principle in engineering project management, which is usually articulated something like this: fast, good, cheap -- pick any two. IOW, if you want it fast, you can have it bad and cheap or good and expensive. If you want it good, you can get it slow and cheap, or fast and expensive. If you want it cheap, you can have it fast and bad, or slow and good.

Now this works for everybody, no matter who pays the bills. The people through their taxes, private investors, retail customers...everybody. For everything NASA screws up, there's ten thousand organizations in the commercial world screwing something up just as bad. When NASA does it right, they get Apollo -- fast and good, but not cheap. Or they do the Mars Exploration Rover program -- a balance of speed and cost that leads to good results. When they get led astray by competing political imperatives, they get the Shuttle and Faster/Better/Cheaper (which, from the previous discussion, should have been obviously flawed to the people who were putting up the money).

In any case, the problem is not with NASA per se. It's with the people putting up the money and what they demand of the money's use. That happens everywhere.

"It should no more be the role of NASA to launch people into LEO than it is the role of the FAA to send people from New York to London. Private enterprises transport people across the Atlantic; the FAA has just an advisory and regulatory role."

NASA isn't a regulatory agency. And there's no ideal or even preferred customer for manned spaceflight. It's no organization's or economic sector's specific business. Anybody who wants to pay can play. Right now, the only primary customers that have come forward are government space agencies. Even the billionaire space tourists are secondary customers, buying space access through a government agency.

Now, that may not be an ideologically correct state of affairs. It's just a realistic one.

More importantly, commercial contractors build all of the hardware, from the ground support equipment, to the launch vehicles, to the payloads. Anybody that wants to come to them and buy manned spaceflight hardware -- and operational support besides -- can. No customers have materialized.

Tony said...

Brian/neutrino78x (2):

"Anyway, just because only 1% of your vehicle can be cargo does not make SSTO 'impossible'. It just means it has to be a large vehicle, so the 1% is reasonably large. You can take the Space Shuttle external tank, put Space Shuttle Main Engines on it, and it will go to orbit. No laws of physics are violated. People used to say it was 'physically impossible' to fit a nuclear reactor on a submarine and do it safely, but they were wrong.
See http://www.spacefuture.com/vehicles/building.shtml"


Oh, brother...

First of all, I said that, using current or foreseen technology: "...reusable SSTO is a physical impossibility." That's a very specific statement that I think I'll stand by.

Let's do a little math. If you look at the easily accessible sources for performance figures, you can figure out that the described stack would weigh 823,000 lb for the tankage (Suttle ET), engines (6 x SSME), and payload (30 tons). The nominal thrust for such a vehicle works out to 3,072,000 lbf. Sure seems like it should be able to get off the ground.

Well...let's look at that in detail. If we run all six engines at nominal thrust, we get an acceleration on the all-up vehicle of 1.78 g. On the empty vehicle, you get 22.26 g of acceleration. That means the average acceleration over 240 seconds at nominal thrust is 22.26 g. So obviously we need to burn all six of the engines only a minute or two after liftoft. By both throttling down and shutting off engines as we go up, we can manage the acceleration. At the end, we have a single SSME thrusting at 67%, providing 2.49 g. (How you're going to arrange the engines to maintain vehicle ballance all the way up is an interesting question.) But all of that comes at the cost of hauling an average of 18,600 lb of non-running engine uphill the whole way (no useless engine weight at liftoff, 37,200 lb of useless engines at burnout).

Maybe, just maybe that will work to get the vehicle in orbit. But only the vehicle, because I think the 30 tons set aside for payload are going to be taken up by:

Avionics
Thrust structure
Vehicle structure*
Assorted plumbing, wiring, and instrumentation

*Remember, the Shuttle ET was not designed to carry a payload on top. It was designed to be carried aloft by rockets attached to it. It was designed with the same kind of mentality that aircraft drop tanks have always been designed with. It could never carry 90 tons (30 tons x 3 g) on top as it is currently built. ISTR that the Ares V and other Shuttle-derived designs envisioned thickening the ET tank walls by at least 50% and adding extra framing in order to turn the tank into a structurally capable launch vehicle stage.

"Just because the engineering is non-trivial does not mean it is impossible to do. Maybe impossible for the NASA of 2011. I bet the NASA of 1969 could have done SSTO, and would have, were it relevant to what they were doing."

Once again, this is speculative engineering vs real world engineering. Asserting that the real world engineers just aren't trying hard enough is specious. Of course they're trying as hard as they can. If they could, they would definitely rather not stage in flight. Staging and lighting engines during ascent are events that any rational engineer would love to avoid. Having all engines running before launch commit actually drove the designs of both the R-7 and Atlas ICBMs, the LVs that first carried men into space. Embracing the idea that NASA engineers or their contractors' engineers are just too incompetent, or that management is just to stuck in the past is evidence of simply not knowing the details of the subject.

Tony said...

Brian/neutrino78x:

Tony, I don't blame NASA per se, I just think that, historically, the government does not provide sustainable commerce. NASA is not good at doing routine things cheaply, quickly, and reliably; that is the domain of commercial enterprise.

There's an old and fundamental principle in engineering project management, which is usually articulated something like this: fast, good, cheap -- pick any two. IOW, if you want it fast, you can have it bad and cheap or good and expensive. If you want it good, you can get it slow and cheap, or fast and expensive. If you want it cheap, you can have it fast and bad, or slow and good.

Now this works for everybody, no matter who pays the bills. The people through their taxes, private investors, retail customers...everybody. For everything NASA screws up, there's ten thousand organizations in the commercial world screwing something up just as bad. When NASA does it right, they get Apollo -- fast and good, but not cheap. Or they do the Mars Exploration Rover program -- a balance of speed and cost that leads to good results. When they get led astray by competing political imperatives, they get the Shuttle and Faster/Better/Cheaper (which, from the previous discussion, should have been obviously flawed to the people who were putting up the money).

In any case, the problem is not with NASA per se. It's with the people putting up the money and what they demand of the money's use. That happens everywhere.

"It should no more be the role of NASA to launch people into LEO than it is the role of the FAA to send people from New York to London. Private enterprises transport people across the Atlantic; the FAA has just an advisory and regulatory role."

NASA isn't a regulatory agency. And there's no ideal or even preferred customer for manned spaceflight. It's no organization's or economic sector's specific business. Anybody who wants to pay can play. Right now, the only primary customers that have come forward are government space agencies. Even the billionaire space tourists are secondary customers, buying space access through a government agency.

Now, that may not be an ideologically correct state of affairs. It's just a realistic one.

More importantly, commercial contractors build all of the hardware, from the ground support equipment, to the launch vehicles, to the payloads. Anybody that wants to come to them and buy manned spaceflight hardware -- and operational support besides -- can. No customers have materialized.

Tony said...

Brian (3):

Correction:

The vehicle weight wouldn't be 823,000 lb, it would be 1,728,000. Everything else is corect. (I transposed kilos for pounds when copying down figures from astronautix.com.)

Tony said...

Brian (4):

Oh yeah...the average acceleration at nominal thrust is not the same as the maximum acceleration. It's the minimum plus maximum divided by two. That works out to 12.02 g.

Tony said...

Re: Thucydides

A laser launch system ("Lightcraft" is latter day marketing spin; the idea has been in print for forty years) for micropayloads is still a huge infrastructure investment. There's no market for it. Micropayloads can piggyback on underutilized LVs going in the right direction, or even launch on a notional future micro LV even smaller and cheaper than Pegasus (or be ganged together two or three at a time on a Pegasus). Too many options already exist and there's just not any demand.

Also, laser launch systems will not scale linearly. One can add capability up to a point. But then further expansion would get to complicated and it makes sense to build a whole new system with fewer, higher power individual modules.

Anonymous said...

Wow, Tony, you really hate the idea of SSTO's...however, since you aren't an astronoutical engineer, I'll take your arguments with a grain or two of salt. While I do share your dissapointment with how the 'future' turned out, I haven't gone to the extreme of pronouncing anything even vaugely smacking of technical advancement as 'impossible'.

Anyway, while SSTO's may not be in the cards, there are several ways that are being explored (at various levels of spending), to improve space launch. Many of them have already been talked about here, so I'll just leave it at that.

However, back to the original topic of this post; getting from orbit of one planet and into orbit of another without having a true torch drive, then a solar or nuclear powered ion (or plasma) drive is probably the way to go. Using these in a modular system, then you mate a mission module, (and maybe a hab module as well), to the drive module and you have a ship suitable for whatever interplanetary mission you desire.

Ferrell

Tony said...

Ferrell:

"Wow, Tony, you really hate the idea of SSTO's...however, since you aren't an astronoutical engineer, I'll take your arguments with a grain or two of salt. While I do share your dissapointment with how the 'future' turned out, I haven't gone to the extreme of pronouncing anything even vaugely smacking of technical advancement as 'impossible'."

One has to remember that "impossible" not only means physically impossible, but impossible in the economic, political, and technical context of the real world. I do think reusable SSTO is IMO manifestly impossible given current or foreseen technologies. SSTO of any type is impossible because it doesn't make anywhere near enough economic sense for anybody to fund it. Multi-stage, expendable LVs exist precisely because they're what we have the ability to actually do.

See, I don't hate SSTO. What I take exception to is uninformed dreams based on wild, unrealistic speculation. I know it's a huge downer to a lot of people, but all I'm doing is presenting the facts.

And while I may not be an astronautical engineer, what the engineers do is get the details worked out. The basic principles are clear enough. Using what the real engineers have managed in the real world as illustrative example is perfectly valid.

Damien Sullivan said...

I don't see how Tony's dogmatism against space habitats can be justified. You can't live outside on Mars, so both in space and on Mars you have to build your entire operating volume. Buildings everywhere, buildings that have to resist low external pressure, extreme temperatures, and radiation. Megastructures? No more so in space than on Mars. Yes, Mars gives you dirt. You still need a floor. You might be able to skimp on the floor, as it comes with air pressure control and radiation shielding, but it also comes with permafrost and the needs of a long-term building foundation.

The ISS is a bunch of modules. Early Mars habitat might be a bunch of modules. Not exactly a lot of difference, except the ISS can use more internal surface area (no off-limits ceiling or upper walls) and has to deal with zero-gee toilets.

Bones will melt away in zero-gee but they'll also melt away on Mars, and we can at least conceive of artificial gravity in space, not so much on Mars. And while O'Neill is a megastructure, with big open area and high ceiling, modules or big bubbles (for the claustrophobic) on a tether aren't.

As for why a habitat -- why anything in space? If physical resources are an issue, you can build next to Ceres, or some near-Earth asteroid, negating much of the advantage of A Planet, and with easier trade with anyone else since you don't have your own local gravity well to fight out of.

But the modern era sees many cities, even countries, which don't have much in the way of natural resources, other than position or even inertia. LA, Las Vegas, Dubai... planetary orbits and Lagranges might end up favored, especially if you can raise healthy kids in rotating gravity but can't on low-gravity Mars. Mars "colonization" might consist of miners overseeing machinery on the surface, sending material up to their families and trade networks in orbit, no doubt rooted in Phobos and Deimos.

*****

As for outer-system solar power, I've seen suggestions for turning around, releasing a light-weight mirror, and letting the mirror concentrate extra light on your panel. Given Mylar balloons, outer solar power might not be as big a problem. Of course, you could use concentration in the inner system, until your panels fry, so there'd still be an energy advantage, but the threshold of getting enough energy to be useful at all can be pushed back.

Anonymous said...

=Milo=



Damien Sullivan:

"Buildings everywhere, buildings that have to resist low external pressure, extreme temperatures, and radiation."

Vacuum offers lower external pressure than Mars's atmosphere.

Heating a hab (which you need to do on Mars, and not even that much because even though the air is very cold, it's also thin and so doesn't cool you down too quickly) is easier than cooling one (which you need to do in space), particularly if you have access to nuclear power. Which you should.

There is less radiation under the shielding of Mars's atmosphere than when you're exposed out in space.


"Yes, Mars gives you dirt. You still need a floor."

The point of dirt isn't to give you a floor. (Except when you spacesuit up to perform external maintainance.) The point of dirt is to give you something you can mine for materials to make concrete, glass, metals, etc. You're going to need a lot of those and hauling them out of a gravity well or across a large distance in space is difficult.


"But the modern era sees many cities, even countries, which don't have much in the way of natural resources, other than position or even inertia."

True, but those places still have access to dirt.

Also, many of them gain their wealth from trade, which requires travel being easy enough to have a significant volume of trade and be able to afford routing it through a nexus.

Damien Sullivan said...

Martian pressure peaks around 0.01 bar, and can go a fair bit lower; that doesn't seem hugely different from zero.

Dirt's useful for materials, yes. As I said, you can build next to Ceres or many other asteroids. Lots of dirt. More than you'll run out of in a long time. And metals not so readily found on planets.

And gravity. What happens when you raise kids in 0.38 g?

"Also, many of them gain their wealth from trade, which requires travel being easy enough to have a significant volume of trade and be able to afford routing it through a nexus."

True, but we need that for pretty much any baseline colonization scenario.

Tony said...

Re: Damien Sullivan

In space you don't just build the structure you live in. You have to build the additional structure to spin it for gees. You have to use a lot of energy to extract HCNO from rocks, or ship one or more of them from hundreds of millions of miles away. On Mars, all you do is walk outside and, if your habitat is well placed WRT permafrost deposits, you can just dig up water, and precipitate carbon, nitrogen, and oxygen out of the atmosphere. Everything just requires less energy and less work.

WRT what a person raised on Mars might be like, well, one could probably never go to Earth. But why would one want to? Earth isn't the be all and end all of the human future.

It's not dogmatism that makes space habitats a very far future, beyond Mars and the asteroids prospect. It's simple practicality.

Jim Baerg said...

We don't have any data to tell us if a human raised in Martian gravity would be healthy even for living on Mars.

I would like to see a moon base or a couple of Bigelow habitats rotating on a tether & a few generations of lab rats raised there to give us such data.

Anonymous said...

Jim Baerg said:"I would like to see a moon base or a couple of Bigelow habitats rotating on a tether & a few generations of lab rats raised there to give us such data."

I agree; any Lunar base should have as one of it's primary purposes to be medical research on the human body in low (as opposed to microgee), to determine the minimum g-load for human health.

Ferrell

Anonymous said...

=Milo=



Tony:

"WRT what a person raised on Mars might be like, well, one could probably never go to Earth."

"Never" is a strong word. People raised in lower altitudes take time to acclimatize to higher altitudes, and get violently sick if they try to rush it, but can still do so. There's no guarantee that gravity will prove similar, but it wouldn't surprise me.

The main problem is that there's no intermediate-gravity area to train yourself in. You're either on Earth or you're in space, and getting from one to the other is pretty expensive so you can't start out taking just a few minutes or hours of Earth gravity at a time. A good approach might be to design the passenger liner for spin gravity, and have it slowly build from Mars gravity at departure to Earth gravity at arrival.



Jim Baerg:

"I would like to see a moon base or a couple of Bigelow habitats rotating on a tether & a few generations of lab rats raised there to give us such data."

Are you talking literal lab rats? While those are certainly a good start, since it's gravity we're talking about, it would be a good idea to experiment with something of comparable size to us. I would expect size (and therefore weight) to seriously affect how gravity treats you. You might also want to pay attention to bipedalism...

Tony said...

Studying long term human health on the Moon doesn't tell you anything about Mars. In fact, if the long term health cutoff happens to be somewhere between .2 and .3 g, doing your experiments on the Moon will lead one to entirely the wrong conclusions about Mars. Just like the previous ages of exploration, each new environment has to be qualified on its own merits.

Jim Baerg said...

However, there is the curious clustering of surface gravity values at ratios of 2.5 (or 0.4). Venus, Earth, Saturn, Uranus & Neptune are all fairly close to 10 m/s^2, Mars & Mercury are both just under 4 m/s^2, & our Moon & the large satellites of Jupiter & Saturn all have surface gravities quite close to 1.6 m/s^2.

So our low gravity biology laboratories in the rotating space station really only need to be at lunar & martian gravity to cover all the data points of interest for solar sytem habitation.

Anonymous said...

=Milo=



Tony:

"Studying long term human health on the Moon doesn't tell you anything about Mars."

A negative result ("unhealthy") on the moon wouldn't guarantee anything about Mars, although it could still give some hints (i.e., does the degree of damage lie proportionally between zero and what people in zero-gravity experience, or is it significantly above or below this value?). A positive result ("healthy"), however, would practically guarantee that Mars is okay too.

Unfortunately, Luna is still pretty heavy as far as moons go, so it still wouldn't be enough to be sure about what'll happen on the various gas giant moons (only Io is dense enough to have a higher surface gravity, and the lack of water means nobody is going to want to settle there), although it's still close enough to give us a good guess.

Additionally, if health problems are encountered on Luna but a treatment is found for them (one which may or may not also work in zero-gravity), then there is a reasonable expectation that said treatment will also be helpful elsewhere.

That said if the specific purpose is solely to test variable-gravity effects on physiology, a rotating station is probably easier to provide than a moonbase. I'd only use a moonbase if I was also planning to do other things with it and the gravity research was just hitching a ride.



Jim Baerg:

"So our low gravity biology laboratories in the rotating space station really only need to be at lunar & martian gravity to cover all the data points of interest for solar sytem habitation."

Those will probably take up much of the experiment's schedule, but since speeding up or slowing down a donut's rotation is fairly easy, you might as well run some experiments on other values as well. Particularly, if Lunar gravity proves okay, I'd want to keep gowing lower and seeing where the cutoff is. Can we still make do with Mimas gravity (just 0.06 m/s/s, or around 1/150th of Earth gravity)?

Tony said...

Jim Baerg:

"So our low gravity biology laboratories in the rotating space station really only need to be at lunar & martian gravity to cover all the data points of interest for solar sytem habitation."

I can't see a realistic path to such a station. I'm with Rick that initial permanent residence will be ad hoc and unplanned. People volunteering to extend tours and (eventually) just stay, will be the subjects of the medical studies. And those studies will be much more relevant because they'll be done on humans in the actual environment being considered for human settlement.

Jim Baerg said...

"rotating space station ..."
I can't see a realistic path to such a station."

A couple of Bigelow style space habs on the ends of a tether 80 m long rotating at 3 rpm to get martian gravity.

What's unrealistic about that?

Tony said...

Jim Baerg:

A couple of Bigelow style space habs on the ends of a tether 80 m long rotating at 3 rpm to get martian gravity.

What's unrealistic about that?

I was talking about "realistic" in terms of motivation to spend the money. As previously stated, likely programs for Mars exploration will probably keep explorers under a certain time exposure to low gee (and cosmic radiation). There will be no reason to spend billions on a rotating hab experiment. People who do adopt long term residence on Mars will do so on an ad hoc basis, and become the experimental subjects themselves, in the actual martian environment.

Anonymous said...

Tony said:"I was talking about "realistic" in terms of motivation to spend the money. As previously stated, likely programs for Mars exploration will probably keep explorers under a certain time exposure to low gee (and cosmic radiation). There will be no reason to spend billions on a rotating hab experiment. People who do adopt long term residence on Mars will do so on an ad hoc basis, and become the experimental subjects themselves, in the actual martian environment."

You seem pretty certain about that. Some people do think that finding out beforehand what the effects of Luna or Mars gravity is on the human body, before they actually go there,(or to further away destinations), would be a good idea. Whether on a spinning station or a Lunar base, medical research should be an importaint part of any exploration program.

Ferrell

Thucydides said...

If things like the ISS are going to be continued, I can see a push for a rotating crew hab just so the crew stays healthy (not to mention no need for a zero G toilet).

For practical reasons you would have two structures, the rotating crew hab, and a stationary structure with "pallets" for various microgravity experiments, mounting the space telescope, etc. For the most part the crew would stay aboard the hab and teleoperate the science experiments, but are there to fix things that need attention.

If they are actually separate items, then you don't have to worry about vibration and rotational torques in the stationary structure, but would need to have more spacewalks to fix things, and the shuttle/cargo ships need to dock at two separate space stations, so logistics and administration becomes a real pain.

Tony said...

Ferrell:

"You seem pretty certain about that. Some people do think that finding out beforehand what the effects of Luna or Mars gravity is on the human body, before they actually go there,(or to further away destinations), would be a good idea. Whether on a spinning station or a Lunar base, medical research should be an importaint part of any exploration program."

When you start looking at the money everything costs, you start realizing that anything you do in space costs so much that putting money into figuring out every angle before doing something keeps you from doing anything. Also, when is enough actually enough? How many decades could be spent goofing around on basic medical research, just to be "safe"? I'm nowhere near as cavalier about human health as Zubrin and his posse is, but there is a point at which you have to say these are volunteers, we know enough to know that they'll probably survive the experience, and we'll find out a lot of what we need to know in the process. You may even find the atro/cosmonauts themselves demanding to go places, rather than spend their space careers in LEO, gathering medical data.

Anonymous said...

Tony said:"When you start looking at the money everything costs, you start realizing that anything you do in space costs so much that putting money into figuring out every angle before doing something keeps you from doing anything. Also, when is enough actually enough? How many decades could be spent goofing around on basic medical research, just to be "safe"? I'm nowhere near as cavalier about human health as Zubrin and his posse is, but there is a point at which you have to say these are volunteers, we know enough to know that they'll probably survive the experience, and we'll find out a lot of what we need to know in the process. You may even find the atro/cosmonauts themselves demanding to go places, rather than spend their space careers in LEO, gathering medical data."

Tony, do you really not understand what people are saying, or do you simply missunderatand on purpose? No one is saying that on-orbit medical research should be the be-all and end-all of a space program; nor are we saying that it should last decades; what we are saying is that some research on human health in different g fields before deciding on whether off-world colonies (or outposts with permanent residents) are possible.

Just a friendly suggesstion; you might want to switch to decaf...;0

Ferrell

Thucydides said...

Moving a bit more firmly in Rocketverse territory is this article: http://lifeboat.com/blog/2011/06/teeming-cities-of-mars

Notice that the assumption is a 20 person "one way colony" is the starting point; this is the sort of prestige project that a nation might choose to do, or something that might just be within the ability of a dedicated team funded by a billionaire or industrial consortium.

With normal growth factors discussed in the article, the colony can grow from 20 to thousands or millions in a very short time (even at a one percent growth rate there are ten million Martians in just over a thousand years. Realistic growth rates like 3.5% bring the population to 15 million in a bit over three centuries). A difficult but achievable starting point (historically this would be a bit like Lief Ericson's Vikings being stranded in Vineland), and has plenty of the elements of Romance for exciting story telling.

Something to think about.

Anonymous said...

Thucydides; piggy-backing my idea of permanent research bases onto your idea, we could see researchers being stationed for several years (multiples of the 2-year launch windows), having children while off-world and deciding to remain instead of rotating back to Earth. That could give us our start of an off-world colony.

Ferrell

Tony said...

Ferrell:

"Tony, do you really not understand what people are saying, or do you simply missunderatand on purpose? No one is saying that on-orbit medical research should be the be-all and end-all of a space program; nor are we saying that it should last decades; what we are saying is that some research on human health in different g fields before deciding on whether off-world colonies (or outposts with permanent residents) are possible.

Just a friendly suggesstion; you might want to switch to decaf...;0"


I understand what people think. I'm just pointing out some realities that people need to think about as well. Nobody is likely to be thinking permanent settlement for a long, long time. Before that happens, there will probably be several expeditions and probably an outpost or two with rotating crews. I'm in agreement with Rick that permanent settlement, if biomedically possible, will organically arrise out of that.

I just don't think there'll be a need for experimental habs. And habs will be seen as an unnecessarily expensive and diverting departure.

Anonymous said...

Tony said:"I just don't think there'll be a need for experimental habs. And habs will be seen as an unnecessarily expensive and diverting departure."

You give people too much credit, sad to say...:(

Ferrell

Thucydides said...

Since electric engines need a source of electricity, here is some recent developments on the nuclear side of the house:

http://nextbigfuture.com/2011/07/high-energy-density-nuclear-power-for.html

How well this translates to actual hardware is up for grabs, but it is reassuring that the magic 1Kg/Kw figure is coming into sight for fans of electric engines. For my part, I would much rather see this sort of technology married to VASMIR type plasma engines (Mars in 39 days, anyone?), but the energy source and thruster are two independent systems, so anyone can mix and match to their hearts content.

KraKon said...

Which nuclear reactors can easily be converted into nuclear thermal drives? This would be particularly be useful for a warship.

Anonymous said...

KraKon: pebble-bed reactors would be good; just remember to use coated fuel pellets, so your exhaust isn't contaminated by spent fuel.

Ferrell

jollyreaper said...

What the hell is up with all the generic "good blog" posts? Are the spammers trying to ruin the filters or something?

Rick said...

Re 'good blog' spam: I don't know what the deal is with that! It doesn't seem to fool the spam filter - it goes into spam jail, and I elf it. Perhaps there may be spam links that are removed before I ever even see it.

As with other spam, it goes out to email subscribers, and there doesn't seem to be anything I could do short of imposing comment moderation.