dystopic

Join Date 10/2005

+41

bussard ramjets, cryonic stasis, and exoplanetary colonization

what will it take?

hello everyone,

i'm a bit of a writer, and i can't help but feel drawn to science fiction. that shouldn't be surprising.

lately i've been reading up a great deal on theoretical physics, exobiological speculation, and all that. i was dismayed at first to learn that the chances of faster-than-light travel being physically possible are slim. it was also pretty discouraging when i sat down and looked at the actual speeds that'd be required to traverse sizable parts of the galaxy in a single conscious lifetime. it was a kick when i was down to learn about how difficult terraforming probably would be. but the more i've been learning, the more i've been excited about telling a different kind of science fiction story.

to draw an analogue to our world, the thing that made both the european colonial age and the modern process of globalization have been technology. it's not that we couldn't go to various places around the world before, it just cost too damn much to make anything worth it. i got my BA in sociology, and these sorts of things interest me.

if FTL travel isn't possible, then more than likely it'll be too damn costly to ever colonize beyond our own solar system as the way it's been envisioned in most of the celebrated scifi universes. But there are examples such as Arthur C. Clarke's Songs of a Distant Earth or Sid Meier's Alpha Centauri where humans colonize to escape destruction on earth.

recently i had the chance to meet both Kim Stanley Robinson and Geoff Ryman. Robinson is a hard scifi writer after my own heart; the Mars Trilogy is a really interesting look at our first attempts to colonize within our own star system. Ryman was actually more interesting to talk to, though. maybe because few people have ever heard of him (i was only there because i work at UCSD where he was being hosted). but i actually got to talk to him. he said he thinks we probably won't ever leave our galactic neighborhood.

i'm interested in writing a hard scifi story (or series) myself. i'm interested from a sociological point of view: what would drive us to colonize space? from a writer's point of view, i want to keep the earth around, so i'm not interested in a flight from disaster. what would societies be like after colonies were established? trade would be difficult, but not impossible. same goes for war.

while i'm certainly interested in contributions along those lines, i'm also interested in learning more about the hard science and engineering behind interstellar travel. i've got a lot of questions i haven't been able to answer through wikipedia and google alone. but i'm not about to list them all here.

it seems like a discussion about real ("real") colonization and space travel could use a place on these boards.

i'll kick it off. i've been reading up on propultion especially, and bussard ramjets seem like the most economically feasible option since they gather their fuel as they go - perhaps especially if it could be hybridized with another form such as antimatter-catalyzed fusion. the wikipedia article on bussard ramjets describe that they'd probably need what is essentially a magnetic funnel or ramscoop to gather interstellar hydrogen as propellant.

The mass of the ion ram scoop must be minimized on an interstellar ramjet. The size of the scoop is large enough that the scoop cannot be solid. This is best accomplished by using an electromagnetic field, or alternatively using an electrostatic field to build the ion ram scoop. Such an ion scoop will use electromagnetic funnels, or electrostatic fields to collect ionized hydrogen gas from space for use as propellant by ramjet propulsion systems (since much of the hydrogen is not ionized, some versions of a scoop propose ionizing the hydrogen, perhaps with a laser, ahead of the ship.) An electric field can electrostatically attract the positive ions, and thus draw them inside a ramjet engine. The electromagnetic funnel would bend the ions into helical spirals around the magnetic field lines to scoop up the ions via the starship's motion through space. Ionized particles moving in spirals produce an energy loss, and hence drag; the scoop must be designed to both minimize the circular motion of the particles and simultaneously maximize the collection. Likewise, if the hydrogen is heated during collection, thermal radiation will represent an energy loss, and hence also drag; so an effective scoop must collect and compress the hydrogen without significant heating.

talk about kick-butt imagery! spirals of heated gas careening towards a ship only to be fused and expelled in a jet plume? sweet.

anyway, i've written enough, and i hope it hasn't put anyone off. some of the the community here has proven to be very well read with regard to these kinds of science, so i thought it'd make a great topic for discussion: all things related to space exploration and colonization with reasonable extrapolations of current technology.

my biggest point of curiostiy was with respect to ramjets, so i'll take the kickoff: could the spiral motion of the inbound gas somehow be harnessed to artficially generate gravity by rotating the ship, instead of producing drag?

any volunteers?

final words: i hope no one minds my double-motive. i won't try to steer any dicussion, though if things quiet down i might pose more general questions to keep it going; i encourage anyone interested to pose your own!

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i think everyone has forgotten something about space.

stellar space is empty.

interstellar space is not.

ie almost everything around a star is pushed away from the star into interstellar space.

where as interstellar space for the most part is a hydrogen cloud.

thus your ion engine won't need to be as big to push your ship at the same speed in interstellar space as it would be in stellar space.

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stellar space is empty.

He has a point; there isn't enough hydrogen in stellar space, so the bussard ramjet wouldn't work here. Which is unfortunate, I thought the idea was awesome.

However, there is Warp drive.

Known as Warp drive colloquially, as it closely resembles the famous engines in Star Trek, the Alcubierre drive is a theoretical system by which one extends a field that compresses spacetime itself in front of your vessel and stretches it behind you. While your ship isn't technically moving faster than light through space, space itself is moving around you and pushing you forwards.

The result: a way around the cosmic speed limit.

This "speed bonus" can work together with conventional propulsion for a really, really fast ship, or you can use the Alcubierre drive alone, and the ship isn't technically moving. This would prevent drastic time dilation effects, which I imagine would be very helpful in a sci-fi novel, cause I would think that going to fight wars and finding them finished once you got there would be bad for the story.

I also want to bring up airponics. Like hydroponics, airponics is a way of growing plants without soil. The difference should be fairly obvious, hydroponics grows plants in pools of nutrient enriched water or pipes with flowing nutrient water; whereas airponics suspends the root systems in air and mists the roots with the nutrient water in timed intervals. Airponics would be particularly advantageous the Moon or Mars, where water supplies are limited, because we could use the water more effectively this way and recycle it easier.

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While I'm personally quite fond of an Alcubierre drive, I'd rule it out for what he's going for. He's talking about hard sci-fi, and the Alcubierre drive is unfortunately a bit far off. Too much of the physics is unknown (it could still be ruled out as a feasible mathematical model) and the engineering requirements are obscene... an incredible amount of mass is needed (on the order of several suns!) and an equal amount of "negative mass". To top it off, there is no known way that a warp bubble could form! While that negative mass quality might be eventually found in exotic matter, it definitly falls into the "magic wand" category of space travel techniques.

To answer your question, you could use that spiraling motion to create the gravity, but there are a few catches:

1) The diameter of the ramjet (or at least the living habitats) would need to be large in order to avoid significant tidal effects. That wouldn't be too comfortable, or healthy, for your space travellers!
2) The rotation would need to be carefully managed. For the most part, all you'd want to do is spin the thing up and leave it there, you don't want it constantly accelerating!

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Hey there!

If you want to see a great movie about a colony on mars... watch Total Recall, this movie is AWESOME!!!

Also, I think the improbability drive makes more sense than whatever you'r talking about!

EDIT: Hold on!?!

1)Cryonic stasis was mentioned in the title of this post, why?

2)I read this in one of the hitchhiker of the galaxy books. If we had sent a ship with our current space drive technology to another planet, by the time it got there, we would have already invented a new space drive technology that would go way faster, so when it got there, whatever it had been sent to do would have already been done.

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so the bussard ramjet wouldn't work here. Which is unfortunate, I thought the idea was awesome.

there is only one thing wrong with this and that is they are using an ion engine on a space probe going to or at the astroid belt.

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so the bussard ramjet wouldn't work here. Which is unfortunate, I thought the idea was awesome.

there is only one thing wrong with this and that is they are using an ion engine on a space probe going to or at the astroid belt.

Which is still in interstellar space. To get to Stellar Space, you would need to get past pluto at least. I.E.: Pretty much escape the gravity well of the sun.

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He has a point; there isn't enough hydrogen in stellar space, so the bussard ramjet wouldn't work here. Which is unfortunate, I thought the idea was awesome.

there actually is a little bit of hydrogen that gets ejected from an active star's atmosphere inside a solar system. it wouldn't go as fast, no, but then it wouldn't need to.

personally, i'd imagine two whole ship drives. some for travel within systems, and some for travel between them. if you hybridyzed a bussard ramjet with an antimatter-inititalized fusion engine powered by onboard hydrogen tanks used as reserves, you could move in systems just fine. the trust principal is the same, you just need to invent a good injection method.

moreover, the lack of fuel and solar wind within a system would be a good thing; it'd help slow the damn ship down. i mean, if it's cruising at 12% light speed, it's gonna take a pretty hefty amount of energy to stop. i'm not imagining cute little ships that land as our first colonies. i'm actually thinking of something more like a space station attached to an engine. it makes more sense from a technical point of view, since it can serve as port of call for future ships. you could even build a space fountain downward from orbit.

the Alcubierre drive is a theoretical system by which one extends a field that compresses spacetime itself in front of your vessel and stretches it behind you.

unfortunately this kind of spacial warp, while theoretically possible to generate, would require negative energy; we don't know how to produce negative energy.

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there is only one thing wrong with this and that is they are using an ion engine on a space probe going to or at the astroid belt.

look up "project orion", "project deadalus" and "project longshot."

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Which is still in interstellar space. To get to Stellar Space,

interstellar is between the stars. stellar is in a solar system.

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space travel will become cheaper when grandma can do it. not saying that there aren't some grandmas who can't do it now.

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unfortunately this kind of spacial warp, while theoretically possible to generate, would require negative energy; we don't know how to produce negative energy.

It's probably more accurate to say that we don't know how to control or harness it. The negative energy could well be the "dark energy" that's pushing galaxies apart. Additionally, the Casimir effect will result in negative energy due to quantum uncertainty.

That said, a warp drive created with the Alcubierre metric is one of those long shot ideas not suitable for hard sci-fi... or if it is, then it certainly needs to take note of all the issues involved. You could, theoretically, base an entire story around the finding of a suitable and plentiful source of anti-gravity materials/technology.

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so the bussard ramjet wouldn't work here. Which is unfortunate, I thought the idea was awesome.

there is only one thing wrong with this and that is they are using an ion engine on a space probe going to or at the astroid belt.

The key difference is the source of ions. A Bussard ramjet would provide fuel for an ion engine by bringing in Hydrogen ions from surrounding space. The ion engines currently being used bring along their own fuel supply in the form of Xenon, which is ionized on-board.

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While it is not possible to move faster than or equal to the speed of light while moving however it is possible to move much fast than the SOL while remaining still. While this may shound like rubish theroreticly it is possible.

If you consider that we are moving much faster than the speed of light when compared to the other side of universe. All that required would be to compress the space between to areas and then move forward over the area where the fold takes place. When space is uncompressed again you will be where you want to be.

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well yes, that's what i was getting at. when there's a net rest energy of zero, what it really means is that there's some negative and some positive energy; theoretical attempts to 'separate' the the negative part of an energy wave or a negative energy particle usually involve a net contributions of energy into the whole system, thus nullifying the negative energy.

1)Cryonic stasis was mentioned in the title of this post, why?

i brought up cryonic stasis because, in my mind at least, it might also be related to the issue of interstellar travel. true, if we can achieve high enough relativistic speeds, time will dialate and passengers wouldn't noticed the earth centuries it takes them to get where they're going. but a truly successful, independant colony is going to need thousands of people to survive without becoming genetically stagnated. keeping humans in some kind of stasis makes sense.

for starters, you don't need to feed them, provide them with air, or manage their waste (at least, not nearly to the extent of a normal, dynamic human). cryonic stasis might also reduce the needs for radiation shielding on the outter sections of a hull.

but these are issues i've barely looked into, to be honest, and my background in biology is much weaker than in physics. when i wrote the original post, i noticed it was getting very long, so i decided not to inundate participants with too many topics at once. if you're eager to discuss cryonic and other means of stasis (whether you think it's possible or not), then please do!

what about my original question? could the spiral torque of the inbound gas in a bussard ramjet be harnessed to produce spin on the ship itself, and therefore a kind of artificial gravity? does anyone know enough about the phsyics of engineering to venture some speculation? even if it didn't reduce drag, could it still be a useful conservation of energy?

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Here's a question, Dystopic - what would the social effects be of relativistic flight? See Poul Anderson's "Tau Zero" for ideas. What happens if the ships themselves are the only form of communication, but a two year (or whatever) ship time becomes fifty (or whatever) in "real" time. The same sort of thing happened in the 17th and 18th century for sea travellers - but their calendar still matched the calendar at home! Add relativistic effects to that and it gets interesting.

The Bussard ramjet is a good idea, but think about the wealth it would take to build such a vessel. This would be like Sir Francis Drake talking about building a 747. There will have to be a huge amount of colonization and development of our solar system before that happens. It would be interesting to do an extrapolation of solar colonization based on the colonization of the New World in the 1700s, with all the socio-political ramifications.

Most SF novels have an assumed orbital industrial infrastructure. The development of this infrastructure could be an exciting read. Again, following a historical model, we could have our current chemical rockets as the Mayflower. Small outposts would be started on the Moon and Mars, but there would be debate about funding. They would become self-supporting and there could be conflict between nations for resources, just as in 1760 North America. I haven't read this sort of story, but I can see the potential!

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hi Oz,

long time, no chat, eh?

you raise excellent points, and they are things i've considered already. thank you very much for the book recommendation; i'm going to check it out from the campus library after lunch.

the sociological (and biological) effects of space exploration are what really interest me; i want to have a solid bio-physical/scientific understanding when i sit down to create these worlds, to lend to credibility if nothing else. but i agree, what really interests me here is how we'd manage trade and communication. what incentive would people have to relocate, knowing that when they get their everyone they knew on earth would probably be dead?

in terms of a story structure, developing our own solar system seems like the most logical place to start (if this were to become a serial): how we get from where we are to a solar empire of sorts. i'd then move into a book focused on colonizing other star systems, followed by one focused on the divergent evolution (social and biological) of human populations separated by such vast stretches. the final logical step for me is first contact with an alien intelligence.

i agree that our own histories of colonization and expansion provide ample material to reflect on, and great insight into the motivations of expansion. presumably we wouldn't bother with expansion unless the home system was going to get something out of it - repreive form over population, much needed resources, or perhaps to quence a burning curiosity. i don't doubt that all those factors and more would come into play; the trick is understanding their relative importance, which is an extension of the state of society at the time such an endeavor is started.

one thing i'm really interested about is how imperial authority would be maintained. the first days of extra-solar colonization would be rough, and colonists would probably be somewhat depenent on supply trains from the Sol system. but as they grew, established planetary bases of operation and cities, infrastructure, they might, like the Americans, desire political self-determination. if there weren't already enforcer ships in the system, they'd take years to arrive; and if they were in the system, . what would war look like?

Ender's Game was pretty interesting, along those lines. except that ansibles probably aren't phsyically possbile, either.

so would pay for colonies? given where we're at now, i can't help but think it'd be private corporate interests. nothing too shocking there. but if they're the ones with such vast resources, they'd probably also manage their own "contract enforcement." if they're going to dump untold resources on setting up a new colony, it'd better pay off for them in the long run. What happens when the colonies decide they've had enough? How do you ensure loyalty of military personnel in such a societal configuration? is the idea to set up a contant supply train, shuttling people and goods back and forth? I don't think Sol-born soldiers would really want to do a tour of duty that'd last centuries in earth time; what would they have to come back to?

It seems rather that they'd have to be promised some sort of extra power upon arrival.

the other motivation for expansion is small groups looking for a space to live more freely. it doesn't seem likely, but perahps small groups an earth would be able to muster up the resources needed to establish independant colonies, though they'd undoubtably face more problems than a supported colony. just some thoughts.

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There will have to be a huge amount of colonization and development of our solar system before that happens.

we have lots of room.

we can colonize mercury. underground.

we can colonize the moon, mars, its two moons, at least half a dozen moons around Saturn, the same Uranus and Neptune. Pluto can be colonized.

plus all the space in between and around. i left Jupiter out because it gives off more hard radiation than the sun does.

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we have lots of room.

i'm not sure what your point is. i don't think anyone said otherwise.

i brought up cryonic stasis because, in my mind at least, it might also be related to the issue of interstellar travel.

well, it seems that cryonically-induced suspended animation is still only tenuously feasible. according to this article, artificially induced hibernation might be a good alternative.

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Well, I can't really commet on the Physics, but I can commnet on the Soc.

Historically, European expansion has almost always been need and adverserial based.

The age of exploration was generally brought on by the desire to trade with the East directly. By accomplishing this, the (christian) nations of Europe would cut out the middle men, which were the (islamic) nations of the middle east. This would allow the Western nations to essentially pinch off the middle east from both sides. You must remember that these nations were very oppoesed to each other in terms of thier religious ideologies to the extent that they were often at war.

The primary reason for exploration was to cut off the middle east economically, so it could be conquered militarily. America was just more of an "accidental find" and initally, Spain just used it as a harvest for gold so It could finance wars in Austria, etc. It wasn't until much later that actual colonization occured (again for economic reasons - but by corporations in the form of investment groups and minority groups, ie Jamestown and Plymouth rock).

The space race seems to have a similar backing. Two competing ideologies racing to get to the moon. While the moon had no resources, there was still a benificial resource to be had from the space race. The resource? Technology. By perfecting our missle technology, we could deliver larger and more dangerous payloads accurately into the USSR. Same goes with them.

I think for your novel, there would need to be an economic and adverserial incentive for colonies. Whether by a government or corporations (or both!), they need to have an incentive (military advantage, technology, resource, etc) and something to compete against.

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If fusion technology takes off, the helium 3 resources that the moon has in abundance may set off a race to put a colony on the moon.

Taking that idea a little further, what could be a greater impetus for colonization than unique (or otherwise rare) resources, especially of the energy variety?

Imagine, for example, a colony that was near enough some potential source of dark matter that doing the appropriate research and harvesting would REQUIRE a colony. Or, perhaps, a planet that was very near to an asteroid belt that was made of antimatter (think of the mining accidents!)

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I think for your novel, there would need to be an economic and adverserial incentive for colonies

i've always passed off the adversarial aspects of the crusades as mainly being propoganda. "in the name of christ" really meant "in the name of the Pope's coffers." at least from a top-down view. it certainly was the sincere motivation for all those thuggish crusaders and sailors to get out there; i just don't know if they would have had that motivation without all those words of encouragement (and promises of rich reward) coming from the church and the crown, respectively. actually, one idea i had was that colonists would find circumstances on their new homes much less enjoyable than they'd been promised.

i indeed had the notion that the colonies would mainly be founded and funded by private interests - who'd perhaps rent out lab space to governmental research organizations and do other similar things to provide immediate returns on their investment. bear in mind that i'm not imagining the first colonial ships would actually ever land. heck, they might even function like Neumann probes ((self-replicating spacecraft)). after a colony ship arrives in a new system, it serves as an orbital base of operations for many generations. once other stations were constructed, as well as permanent planetary bases, the colony ship could restock itself with people, provisions and fuel, and also perhaps make suggested upgrades sent from Earth (or engineered there) -- and be on its way to another system. that new colony could also start building more colony ships.

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i see mining ships using robot miners. not actually mining but cutting astroids up and taking the pieces back to the ship for processing. because there wouldn't be anything in an astroid that wouldn't need to be used. except maybe the holes.

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i somehow missed this post the first time, and it's pretty interesting. however,

fusion is the basis of the bussard ramjet. however to produce thrust, you don't need to gather very much dueterium or trintium from interstellar space. if you gather a little and successfully fuse it, the resulting energy output will be more than enough to excite the standard 1-hydrogen and use it as propellant. now generating electricity is another issue.

one thing i've read is that it might be more optimal for us to use the CNO cycle to fuse regular hydrogen, as it's much more abundant.

as for antimatter, it doesn't seem to occur in any appriciable quantity in the observable universe. while's it's possible that there are regions of space full of antimatter instead of the matter we consider regular, the question remains: where?

i've actually also thought about antimatter. i mean, it's a potential source of energy that far exceeds most others. but the problem is with actually producing antimatter. i got this from the wiki article on antihydrogen:

In recent experiments carried out by the ATRAP and ATHENA collaborations at CERN, positrons from a sodium radioactive source and antiprotons were brought together in a magnetic Penning trap, where synthesis took place at a typical rate of 100 antihydrogen atoms per second. Antihydrogen was first produced by these two collaborations in 2002, and by 2004 perhaps a hundred thousand antihydrogen atoms were produced in this way.

The antihydrogen atoms synthesized so far have a very high temperature (a few thousand kelvins); they will hit the walls of the experimental apparatus as a consequence and annihilate. A potential solution to this problem would be to produce antihydrogen atoms at such a low temperature (perhaps a fraction of a kelvin) that they can be captured in a magnetic trap.

i've been reading about several different types of engine prototype. one type is antimatter-catalyzed nuclear propultion, which would involve using a small pellet of antimatter to intialize a nuclear reaction with what'd normally be a subcritical mass to induce further fission or even fusion (a la H-bombs). yet another, VASIMR involves using radio waves and magnetic fields to compress interstellar hydrogen into plasma and funnel it through a magnetic nozzel.

is it me, or does it seem like these proposed engines are sort of like siblings to varying degrees? i mean, any sort of fusion, if it's for propulsion or electricity or both, is going to require magnetic containment. and the most abundant source of propellant seems to be interstellar gas. but if you could reliabily ionize 100% of that gas using radio waves, you'd still need to 'scoop' 10^18 cubic meters of space to gather just 1 gram of hydrogen (that's a cube with sides about 1,000 kilometers long - though it'd probably be sweeping in cylinders).

you'd need to make a probe as small as possible. but for a colony ship? well, the same principle applies generally. if a colony ship were built to be reusable rather than 1-way, and double as a construction yard for certain facilities and a space dock when not in transit, "small" isn't really much of an option. so let's throw in a particle accelerator. that way we could produce antimatter to induce fusion, both for thrust and generating electricity. perhaps it could double or augment the mechanism needed to construct a space fountain from orbit. many visions of such craft already focus on large ring shapes, so it could fit in there if the ship were big enough.

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here is a ponder.

anti matter has the reverse charge of matter. however if you lived in an anti matter would you see those charges the same as what we see or the opposite.

what i mean

normal matter has electrons. anti matter has positrons. so in the anti matter universe would those positrons be looked at as electrons or positrons

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Mystikmind

Join Date 06/2004

+20

Time and distance are connected. You could say that time actually creates distance, so if you want to travel great distances then you have to de-create time.

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