NationStates Jolt Archive

I was wondering, would a generation ship (im assuming you know what that means) actually work? This is not an rhetorical question, im asking in case there are any scientists here who could answer.http://en.wikipedia.org/wiki/Generation_ship

I was wondering, would a generation ship (im assuming you know what that means) actually work? This is not an rhetorical question, im asking in case there are any scientists here who could answer.

hmmm, it would be interesting if you provided a link or something, so that people who don't know what you're talking about could join the "discussion"

Considering biosphere II was a failure, and a generation ship would probably even need more than 8 persons to function, I fear that it won't :(

I think for a Generation Ship to be a viable option it would:

-Have to provide capacity for a large enough crew to avoid genetic bottleneck

-Have to recycle 100% of all supplies

-Have to tightly regulate population to keep it within the ability for the ship's recycling supply system to support it.

-Have to have a strong leadership structure and strict laws governing the conduct of the passengers.

There was a fascinating novel I read about a year and a half ago Rendezvous with Rama (http://en.wikipedia.org/wiki/Rendezvous_with_Rama) It was about a large cylindrical ship of this type that passes through our solar system. A ship from Earth manages to land on it and gain entry, to find that the cylinder is hollow inside, with artificial gravity supplied by centrifual rotation. The inside surface provided for housing space, food growth and water reservoirs. The crew/passengers were all gone except for mechanical robotic maintanence units and it was a mystery where they went.

You'd be better off finding ways to develop travel that is as close to the speed of light as possible (and FTL, if possible) rather than try to maintain a generation ship, which comes with its own host of problems. Also, it would be better to have the existing crew stay alive for the journey, either active or in the form of some kind of preservative state.

There are no physics reasons why a generation ship cannot work. There's a whole host of problems with that approach, but technically it ought be doable. It'd have to be launched from space though rather than planet-bound.

I think for a Generation Ship to be a viable option it would:

-Have to provide capacity for a large enough crew to avoid genetic bottleneck

-Have to recycle 100% of all supplies

-Have to tightly regulate population to keep it within the ability for the ship's recycling supply system to support it.

-Have to have a strong leadership structure and strict laws governing the conduct of the passengers.

There was a fascinating novel I read about a year and a half ago Rendezvous with Rama (http://en.wikipedia.org/wiki/Rendezvous_with_Rama) It was about a large cylindrical ship of this type that passes through our solar system. A ship from Earth manages to land on it and gain entry, to find that the cylinder is hollow inside, with artificial gravity supplied by centrifual rotation. The inside surface provided for housing space, food growth and water reservoirs. The crew/passengers were all gone except for mechanical robotic maintanence units and it was a mystery where they went.

If you want to find out what the deal was with that ship, read its sequels.... authored by Clarke, and co-authored by Gentry Lee... "Rama II", "The Garden of Rama", and "Rama Revealed"....

The problem would be sustaining a crew for that long. No ship is a closed system. It would depend on the estimated length of the journey - how far and how fast.

I have nothing to contribute to this discussion other than I found out what a generation ship was purely by accident about a week ago. Damn wikipedia and your addictive nature...

Aren't there problems with sheilding the crews from radiation as well?

Physics-wise, not really.

Psychology-wise, absolutely. People go extremely mental when basically every decision is life or death, and running a spaceship holding people both young and old is certainly that kind of decision.

Also - osteoparosis hell upon landing.

The problem would be sustaining a crew for that long. No ship is a closed system. It would depend on the estimated length of the journey - how far and how fast.
The whole point of a generation ship is basically that it's a self-sustaining closed system, used for slower-than-light travel to planets which are a Very Long Way Away.

A generationship is a poor plan. Gravity can be dealt with through grav rings, sections of the ship that spin to simulate gravity. The real problems would be with supplies and finding enough people willing to get on a ship and die in transit. You'd be better off putting a bunch of teens in cold sleep, a sort of hibernation because freezing someone is fatal, and waking them up in their 40's at the new planet a few hundred years later. Yes, I know they'd really be a few hundred years old but cold sleep is supposed to slow aging and reduce life-support consumption.

Also, you'd need a strong drive to get where you were going, chemical rockets would take thousands of years to get to even the closest stars. A nuclear rocket or some kind of space-folding drive is the way to go. If you go for the latter and it disapears only to show up 7 years later in Neptune orbit, don't bother with the rescue party, just scuttle the ship.

I have nothing to contribute to this discussion other than I found out what a generation ship was purely by accident about a week ago. Damn wikipedia and your addictive nature...

I agree.....

There are no physics reasons why a generation ship cannot work. There's a whole host of problems with that approach, but technically it ought be doable. It'd have to be launched from space though rather than planet-bound.Depends on what you mean by "physics reasons". Unless we're talking about a megastructure, radiation shielding and environmental integrity are very damn difficult to preserve. I'm guessing impossible. The best idea I've heard is to build a massive ice hull, but even that idea is hardly unproblematic - and there's the problem of building it, of course.

Depends on what you mean by "physics reasons". Unless we're talking about a megastructure, radiation shielding and environmental integrity are very damn difficult to preserve. I'm guessing impossible. The best idea I've heard is to build a massive ice hull, but even that idea is hardly unproblematic - and there's the problem of building it, of course.
If you could mine asteroids or mars that would take care of the raw materals without totally depleteing earth.

If you go for the latter and it disapears only to show up 7 years later in Neptune orbit, don't bother with the rescue party, just scuttle the ship.

:p

I think it would be rather difficult with foreseeable technology to manufacture what amounts to a perfect environment.

I agree with Vetalia. To reach other stars, we must find some way to make FTL travel possible. With how much our knowledge of how the universe works has increased over the past century or so, I believe it's just a matter of time before we learn how to sidestep those pesky laws of physics.

I think it would be rather difficult with foreseeable technology to manufacture what amounts to a perfect environment.

I agree with Vetalia. To reach other stars, we must find some way to make FTL travel possible. With how much our knowledge of how the universe works has increased over the past century or so, I believe it's just a matter of time before we learn how to sidestep those pesky laws of physics.

Maybe, maybe not, it is not certain at all that we could do such a thing, but then again maybe im wrong.

Maybe, maybe not, it is not certain at all that we could do such a thing, but then again maybe im wrong.

I think it is. Even now, we are beginning to find contradictions of physical laws we once thought absolute. It's only a matter of time before we find the winning combination that will let humans sidestep physical laws.

If you could mine asteroids or mars that would take care of the raw materals without totally depleteing earth.Not that I can see how you'd actually do this, but let's just assume it's feasible. It still doesn't solve the problem of fashioning a vessel generations of human beings could survive in.

I think it is. Even now, we are beginning to find contradictions of physical laws we once thought absolute. It's only a matter of time before we find the winning combination that will let humans sidestep physical laws.

A matter of fairly short time, really, given exponential progress in the tools we use for scientific discovery. Really, I think we will have the knowledge to do it long before we actually build it and it will be used on Earth and in the local solar system for short-distance purposes long before anything else. The thing is, of course, that interstellar travel isn't necessary yet. Now, give us a few generations of continued exponential economic and population growth, and it becomes necessary. We're on the fast track to The Last Question and all that.

If you could mine asteroids or mars that would take care of the raw materals without totally depleteing earth.

Mining asteroids and other planets would remove the need for interstellar travel for a pretty long time. Of course, it would also help explore the various engineering techniques and problems of interstellar travel making it easier to achieve once the need arises.

Really, asteroid mining is a pretty near term prospect (of course, my 'near term' is pretty large), so it's likely we'll see that as soon as private space travel and economic development of space begin to take off in the next 20 years or so.

Almost anything is possible if given enough resources and a few centuries to develop the technology. You would have to construct a huge vessel with massive resources for the journey. Even if you managed 100% recycling, you will still be losing a lot of material (especially atmosphere - it will bleed through the solid hull) and would thus need to carry massive resources along with you.

I find it funny that there always seems to be a contingent of people who suggest that 'mining asteroids' is a valid counter to any lack of resources argument. There is hardly any mass in the asteroid belt and what little is there, is spread across a truly massive volume of space. While there may be a significant amount of material there, it is scattered so much that you're likely to expend more resources in going after it than what you can recover. Forget what you see in the movies, the asteroid belt is mostly empty space with handfuls of dust.

Almost anything is possible if given enough resources and a few centuries to develop the technology. You would have to construct a huge vessel with massive resources for the journey. Even if you managed 100% recycling, you will still be losing a lot of material (especially atmosphere - it will bleed through the solid hull) and would thus need to carry massive resources along with you.

I find it funny that there always seems to be a contingent of people who suggest that 'mining asteroids' is a valid counter to any lack of resources argument. There is hardly any mass in the asteroid belt and what little is there, is spread across a truly massive volume of space. While there may be a significant amount of material there, it is scattered so much that you're likely to expend more resources in going after it than what you can recover. Forget what you see in the movies, the asteroid belt is mostly empty space with handfuls of dust.

A survey (http://www.crystalinks.com/asteroidbelt.html) in the infrared wavelengths shows that the main belt has 700,000 to 1.7 million asteroids with a diameter of 1 km or more.

Over 200 of the asteroids in the belt are larger than 100 km. The biggest asteroid belt member, and the only dwarf planet found there, is Ceres. The total mass of the Asteroid belt is estimated to be 3.0-3.6X1021 kilograms, which is 4% of the Earth's Moon. Of that total mass, one-third is accounted for by Ceres alone. The eleven largest asteroids contain about half the total mass within the main belt.

It's certainly feasible.

Also - osteoparosis hell upon landing.

I thought that was only a problem in zero gravity because of a lack of weight bearing exercise

The whole point of a generation ship is basically that it's a self-sustaining closed system, used for slower-than-light travel to planets which are a Very Long Way Away.

A totally closed system is impossible. The ship will lose energy and matter over time. We try to minimize it, but the ship can only go so far before things fall apart.

It could work, though it would require an trememdous amount of resources.

I just came here to say "The Starlost." That is all.

I just came here to say "The Starlost." That is all.

Ooh what a glorious concept, damn shame it wasn't done right.

Maybe, maybe not, it is not certain at all that we could do such a thing, but then again maybe im wrong.

Again: biosphere 2 was a complete failure. Not just due to the technical limitations, but also due to the interpersonal relations between the bionauts.

I agree with the guy who said that the best way would be to have a FTL, or more realisticly hybernation tubes or whatever you call them. The best colonists would be the gung ho adventurures the greedy and the opressed kinda like europe when it colonized america. But you would need to make sure the planet is habitable, it would be a huge waste of resoures and personel if blip they arrive no planet blip they die.

I agree with the guy who said that the best way would be to have a FTL, or more realisticly hybernation tubes or whatever you call them. The best colonists would be the gung ho adventurures the greedy and the opressed kinda like europe when it colonized america. But you would need to make sure the planet is habitable, it would be a huge waste of resoures and personel if blip they arrive no planet blip they die.

Nah, just start firing ships full of convicts at likely planets. Sure some will die but some will live and if we leave it a couple of hundred years we should get a radio message something along the line of 'G'day mates'.

It could work, but it will have to be LARGE. Big enough to carry enough people to avoid genetic problems, supplies to repair the ship, and room to grow their own food. recycling would be a must. and that's not even going into fuel and computing power.

It could work, but it will have to be LARGE. Big enough to carry enough people to avoid genetic problems, supplies to repair the ship, and room to grow their own food. recycling would be a must. and that's not even going into fuel and computing power.

Think Beam-powered (http://en.wikipedia.org/wiki/Starwisp) sails. No need to carry much fuel or reaction mass. There are technical problems, but it's a way to propel a ship to a significant fraction of the speed of light without engines. Just load the ship up with landing craft or short range vehicles for when they reach the target.

Propulsion issues are not the main problem. Creating a sustainable ecosystem that can can support a crew for generations is.

Unfortunately most people subconciously think of Noahs Ark and therefor assume it to be trivial. Unfortunately Noahs ark is nothing but a myth: such a simple system does not work.

Nah, just start firing ships full of convicts at likely planets. Sure some will die but some will live and if we leave it a couple of hundred years we should get a radio message something along the line of 'G'day mates'.
Go watch the anime "Crests of the Stars". Captain Sporh thinks along the same line when dealing with Enemy Prisoners. :p

Think Beam-powered (http://en.wikipedia.org/wiki/Starwisp) sails. No need to carry much fuel or reaction mass. There are technical problems, but it's a way to propel a ship to a significant fraction of the speed of light without engines. Just load the ship up with landing craft or short range vehicles for when they reach the target.

but you'll still need a backup system to deal with any emergencies.

Think Beam-powered (http://en.wikipedia.org/wiki/Starwisp) sails. No need to carry much fuel or reaction mass. There are technical problems, but it's a way to propel a ship to a significant fraction of the speed of light without engines. Just load the ship up with landing craft or short range vehicles for when they reach the target.
do you think before you type or are you just stupid? Sails in space just don't work. They lack the same thing that ion thrusters do, acceleration. It would take a month for a ship using an ion thruster running on solar cells to get to the moon. Even longer for a sail ship of any variety.

I understand that the idea is velocity, not acceleration but even if you did somehow get to that magic 20% proposed by Forward you'd run a foul of cosmic rays which would damage the ship at the subatomic level. And I don't think I need to tell you about the diffraction limit problem.

The fastest kind of ship in both acceleration and velocity would be an NPR of some kind. The plasma stagnation only lasts a tiny fraction of a second so the plate should remain intact and it has the highest exhaustr velocity and thrust of any rocket, in the range of 10,000,000 m/s and meganewtons. The best thing about an NPR is that the larger the payload, the more efficient the rocket becomes. An anti-matter dirven version could potentially achieve 50% c, a fusion driven version could get 10%. Imagine getting to Alpha Centauri in 10 years or 40 instead of 10,000.

do you think before you type or are you just stupid? Sails in space just don't work. They lack the same thing that ion thrusters do, acceleration. It would take a month for a ship using an ion thruster running on solar cells to get to the moon. Even longer for a sail ship of any variety.

I understand that the idea is velocity, not acceleration but even if you did somehow get to that magic 20% proposed by Forward you'd run a foul of cosmic rays which would damage the ship at the subatomic level. And I don't think I need to tell you about the diffraction limit problem.

The fastest kind of ship in both acceleration and velocity would be an NPR of some kind. The plasma stagnation only lasts a tiny fraction of a second so the plate should remain intact and it has the highest exhaustr velocity and thrust of any rocket, in the range of 10,000,000 m/s and meganewtons. The best thing about an NPR is that the larger the payload, the more efficient the rocket becomes. An anti-matter dirven version could potentially achieve 50% c, a fusion driven version could get 10%. Imagine getting to Alpha Centauri in 10 years or 40 instead of 10,000.

Nice flame, NPR, I assume you mean nuclear pulse propulsion. You bring up
cosmic rays and think detonating a chain of nukes as an engine is better?

In order to move through space while sustaining a livable environment, there would have to be a lot of things to take into account, not the least of which is how our bodies would react to being in a completely artificial environment. That means this - no sun, no heat energy, no nature to surround us, no trees to create oxygen, and a single breach of the airlock could spell certain doom for many, if not all.

We would need a massive ship in order to sustain genetic diversity. We would need some way to duplicate Earth's agriculture - that means water (which would have to be recycled,) large areas of farmland combined with some major genetic modification, and enough space for people to live. Maintenance would be extremely important, as would a good ventilation system - disease could be a pretty disastrous thing aboard a generation ship. If someone contracts some disease like the flu, it could mean certain doom for the vast majority aboard and a major problem replenishing the population.

It's entirely possible to subsist on a vegan diet aboard a generation ship, especially if genetic modification comes into play. People would probably have to take a vitamin supplement every day for protein, vitamin D, and other things we would miss from having no sun and no animal products - but it would be workable. We would probably also have to make sure our immune systems are up to snuff for whenever we land on a planet - any planet that has life on it also has God-knows-what as far as diseases go. Landing on a planet with some disease could turn any journey into the end of War of the Worlds - we all die from some terrible, unforeseen disease because our immune systems can't handle bacteria.

Resources would be a major issue - we would have to find a way to duplicate the carbon-dioxide-into-oxygen effect of trees. We would need water. We would need to find a way to recycle everything - and I do mean everything. Solid waste may be turned into fertilizer; liquid waste may serve a similar purpose. (Yes, it sounds gross. Yes, it's also workable. My wife's step-dad was in Vietnam, and the way they farmed involved a two-field system. One field was for growing crops; the other was for defecating. They would alternate years as to which field was which.)

Resources would have to be kept to an absolute minimum of usage - measures to make the American Indians and Depression-era farmers seem downright wasteful by comparison would have to be enacted. Equivalents of all-natural products would have to be used in order to, say, clean dishes and wash clothes. It may be even such a thing that finger foods are encouraged and people are pressured into wearing as little clothing as possible simply because clothing takes water and resources to clean.

Scientists would be prized. So would recreationists, athletes, and entertainers, since having something to do aboard the ship would be of the utmost importance. Variants on modern sports would be invented to take place in smaller arenas. Sex may be a pastime, but measures to keep the population within a pre-set "population limit" would be kept and would have to be strictly enforced. Possibilities may include, and these may sound horrible but may be necessary aboard a generation ship - child limits (a la the modern PRC,) forced sterlinzation and growing people in vats (a la some bizarro science fiction,) death sentences for reaching a certain age (a la Logan's Run, although I'm sure we can let people live past 30,) or a death sentence for having too many children (with the children being sterilized and placed under government care.)

Also an interesting question is how to enforce law and order aboard a generation ship. It's easy to set a chain of command. What happens if we get an equivalent to the Wahhabists or a fundamentalist Christian group that wants to bring about the End Times? Aside from ensuring that a ship has no single point of failure (i.e. a single puncture in the airlock, electrical, air circulation system, etc. wouldn't bring about everyone's horrible death) it's a question of how to deal with extremists, especially those who would harm individuals or society. Killing them should be a piece of cake - just shove them into the airlock and out into space to explode (my concept for the disposal of dead bodies involves this as well.) However, is that an example we want to set? A generation ship may be somewhat more barbaric than life on any planet simply because the stakes are higher and it's far easier to bring about everyone's death. People might survive a nuclear attack, a volcanic eruption, or a massive bombing campaign; they will almost certainly survive a disease outbreak. No one will survive a ship's complete destruction.

The biggest question is this - what kind of people would sign up for a mission of this measure? An interesting mix of people would volunteer for such a mission - people with nothing left to live for on Earth, space enthusiasts, science fiction fanatics, the desperately poor, and maybe even those who are persecuted. People aboard the ship may not get along, especially at first, and people may form divisions.

Also, how would something that size get off the ground? Something the size of a city may push into the Earth. It would have to be launched in pieces.

The technology isn't here yet, and the practicality and need aren't there. But someday, it could come in handy.

Propulsion issues are not the main problem. Creating a sustainable ecosystem that can can support a crew for generations is.

Which, of course, is why generation ships are pretty much a huge waste of time. It's simply not worth the difficulty of creating a self-sustaining ecosystem when it would be a lot more productive to find ways to both travel at light speed or faster than light and use technology to keep the existing crew alive and/or in stasis.

If you go for the latter and it disapears only to show up 7 years later in Neptune orbit, don’t bother with the rescue party, just scuttle the ship.
Bugger me, that’s a freaky film.

Sending star wisps, relatively small ships with no living humans on board, full of uploaded humans running slower than real time would probably be much cheaper and faster than generation ships.

Generation ships are full of problems. A draconiam government would need to be put in place to limit births and protect the fragile ecosytem. Humans tend to balk at this after a few gnerations. Then there is plain cultural drift. Cultures change very fast. Where is the necessary continuity for survival when the first and last generations resemble each other about as much as we do the the Anient Greeks? Then there's just the expense needed to build the ship in the first place. Even when much of the solar system is inhabited sending a ship with no hope of economic pay-offs it makes little sense to invest in a giant ship.

Also, you'd need a strong drive to get where you were going, chemical rockets would take thousands of years to get to even the closest stars. A nuclear rocket or some kind of space-folding drive is the way to go. If you go for the latter and it disapears only to show up 7 years later in Neptune orbit, don't bother with the rescue party, just scuttle the ship.

Those poor teenagers... :p

Nice flame, NPR, I assume you mean nuclear pulse propulsion. You bring up
cosmic rays and think detonating a chain of nukes as an engine is better?
With sufficient plate thickness and seperation distance radiation from the charges shouldn't be a problem. Nearly everything that could go wrong with the Nuclear Pulse Rocket was worked out 40 years ago during the first engineering study. The team even built 2 prototypes to see if the ships would just be destroyed by the blasts. The prototypes held together and there was even a video of one of the tests floating around the interwebz a while back. The reason that we don't have cheap, efficient space-travel today is because of the testing ban. If you can't set off nukes then Orion ships become useless. Damn hippies ruined science!

I remember visiting a generation ship once. I believe they called it "Earth"...

There's a much simpler solution to generation ships. Terraform Jupiter's moons. Colonize them. Stick a hugeass fusion rocket in Jupiter which can feed on Jupiter's gases. Launch Jupiter towards target system.

Try to avoid smacking into other planets on arrival.

The fusion rocket will act as an artificial sun, and Jupiter will take its moons with it when it goes on the trip.

There's a much simpler solution to generation ships. Terraform Jupiter's moons. Colonize them. Stick a hugeass fusion rocket in Jupiter which can feed on Jupiter's gases. Launch Jupiter towards target system.

Try to avoid smacking into other planets on arrival.

The fusion rocket will act as an artificial sun, and Jupiter will take its moons with it when it goes on the trip.
No.

I was about to give a detailed explaination of the at least eight different ways in which that is fucked up but I'm just going to say no.

Well, you'd need to have lots of horny teens onboard the ship...

No.

I was about to give a detailed explaination of the at least eight different ways in which that is fucked up but I'm just going to say no.

Retort. I was going to give a detailed explanation as to why you were wrong, but I'm just going to say "retort".

I win the argument.

Also, your previous rebuttals have some problems themselves.

Another angle a lot of people forget: by the time the generation ship reaches its destination, its culture will be so utterly changed from that of Earth that there would likely be huge difficulty in reestablishing communications and relations. We would effectively create an entire other civilization that has nothing in common with Earth, so it's likely there would be little direct benefit in using this type of method.

Now, if we were attempting some kind of Scattering a la the Dune novels, this might be a good idea; the goal in this case isn't to create a cohesive space civilization but to seed humanity in as many places as possible.

Now, if we were attempting some kind of Scattering a la the Dune novels, this might be a good idea; the goal in this case isn't to create a cohesive space civilization but to seed humanity in as many places as possible.

If we are able to freeze embryos and sperm, then time is not an issue, once you are with in say 16-18 yrs of you destination the "creation" process is started and life support/education/mission objectives are programmed and deployed. Massive resources are not a problem, it could be and ark with every species, it could even land and then start.

I remember visiting a generation ship once. I believe they called it "Earth"...

That's not a generation ship, that's a generation merry-go-round.

That's not a generation ship, that's a generation merry-go-round.He has a point though. Maintaining the environment is pretty hard to do, without resorting to megastructures. And if you do that, then why bother going anywhere?

He has a point though. Maintaining the environment is pretty hard to do, without resorting to megastructures. And if you do that, then why bother going anywhere?

True. Which is why I consider the generation ship implausible in general, simply because a working generation ship will be capable of supporting its population in and of itself; if you can do that, there really isn't a need for colonization since you can just use the ships instead.

So, it makes a lot more sense to find a way to get the same people and resources to and from a given extrasolar planet than to try to create a self-sustaining ecosystem on board a generation ship. Let the planets support the people and just use the ships to get them there; otherwise, it's a lot of resources spent to create something that already exists.

So, it makes a lot more sense [...]I completely agree. A generation ship is one of those ideas that makes for good storytelling, but very little else.

I completely agree. A generation ship is one of those ideas that makes for good storytelling, but very little else.

That's true. Of course, I don't particularly care what method is used as long as interstellar travel happens...

The only real problems I see are shielding and genetic bottlenecking. Of course the genetic problem could easily be remedied with current advancements in cryogenics. Have the crew "sleep" in shifts and slowly age could cut down in population size while maintaining resources, and motivation of goals. Deep space radiation poses another threat of harming crew, and ship alike. Probably the best thing to do would be magnetic shielding to bend and divert harmful gama rays and cosmic rays. On the plus side power sources would not be so much as a problem like in the past. The ship could use nuclear propulsion, and and excess energy needed could be compensated with ion drive like generators as used by Deep Space One.

Radiation is a huge problem on any long term expedition. Not just it's direct effects on humans, but it's effects on the artificial ecosystem are not to be discounted.

That's true. Of course, I don't particularly care what method is used as long as interstellar travel happens...I agree. Confining ourselves here, even if we do eventually adopt sustainable living, is begging suicide.Radiation is a huge problem on any long term expedition. Not just it's direct effects on humans, but it's effects on the artificial ecosystem are not to be discounted.The problem works both ways. The environment will both break down the hull, and leak through it. With a very limited hull and very limited resources, that combination in itself quickly creates a lethal environment.

It's not that the same phenomena doesn't apply to megastructures, planets and suchlike. It's simply that at that scale, things like atmosphere and whatnot, is replaced as fast as it leaks off into space. Aboard a spaceship, that simply isn't possible, because there's nothing to replace it with.

I agree. Confining ourselves here, even if we do eventually adopt sustainable living, is begging suicide.

Yup. We could be as Earth-friendly and sustainable as we want, but the kind of stuff that could really pose a threat to our survival doesn't care about that. Space colonization creates backups for human civilization in the event that the unimaginable happens, and the more we create the better off we will be.

Not to mention there's an innate desire to explore and settle that will drive us out there...not to mention the time-honored human tradition of wanting to make a buck in the process.

Yup. We could be as Earth-friendly and sustainable as we want, but the kind of stuff that could really pose a threat to our survival doesn't care about that. Space colonization creates backups for human civilization in the event that the unimaginable happens, and the more we create the better off we will be.

Not to mention there's an innate desire to explore and settle that will drive us out there...not to mention the time-honored human tradition of wanting to make a buck in the process.Again, we're in complete agreement. Although I'm more worried about suicide by technology than random disaster. From a species-POV, I think it's insane there wasn't at least Mars and Lunar colonies when I was 10.

Again, we're in complete agreement. Although I'm more worried about suicide by technology than random disaster. From a species-POV, I think it's insane there wasn't at least Mars and Lunar colonies when I was 10.

Unfortunately, a lot of people don't think on those timeframes or on species-level terms; it was extremely expensive, and it made a lot more sense for some reason to pile that money in to developing new ways to kill each other than to build a lasting future for mankind.

I was wondering, would a generation ship (im assuming you know what that means) actually work? This is not an rhetorical question, im asking in case there are any scientists here who could answer.http://en.wikipedia.org/wiki/Generation_ship

i'd say the main question is one of environment. it takes, or so it is currently understood, and seems quite compellingly likely, a VERY diverse invironment to create a sustainable one, and one capable of sustaining human life. on capable of continuing relyably to produce breathable oxigenated air for example.

if we never find a way to cheat the speed of light, a genaration ship is the only way humans, under their own power, can/will ever reach any other solar system then our own, likely to have one or more planets likely to support life, and possibly, "intelligent" life, as we "know" it, other then, those within 10 to 20 lightyears of our own. (there are a FEW candidates there, but not many).

at any rate, that IS the one 'sure', that is to say sure if we can equip them with self sustaining ecosystems, way of reaching and 'meeting the neighbors'.

of course return trips and any news they may bring, will arrive back so much longer after their first departure that it is quite possible there may not even remain historical records of their having left.

i, for one, none the less feel it would be worth doing. if only for what could be learned in making the attempt. but also that there is a great deal more to be learned by doing so besides.

i hope, if and when, or if one might already have, something like a generation ship from some other world were ever to visit us, we don't act like militaristic ass holes when they do.

of course no one can ever count on how anyone else will react to themselves, even on one's own planet or even local community.

cautious without overt hostility would seem to make the most sense.

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i'd say the main question is one of environment. it takes, or so it is currently understood, and seems quite compellingly likely, a VERY diverse invironment to create a sustainable one, and one capable of sustaining human life. on capable of continuing relyably to produce breathable oxigenated air for example.The real complication is radiation leakage both from without and within. A tolerable environment could be maintained artificially, if that problem could be solved. There's no need to create something akin to the geosystem, though you're right about that being too complicated to be feasible.i hope, if and when, or if one might already have, something like a generation ship from some other world were ever to visit us, we don't act like militaristic ass holes when they do.

of course no one can ever count on how anyone else will react to themselves, even on one's own planet or even local community.

cautious without overt hostility would seem to make the most sense.It's not a realistic concern. Anything capable of communicating with us in person, also has the capacity to send something else our way at relativistic speed. As such, anything capable of initiating physical contact, can obliterate the planet utterly, with almost no effort, and do so in a way that is impossible to defend against.

Apart from that, interstellar hostilities, even with the very best imaginary technology, is a logistics and time-differential nightmare. It's completely unrealistic to suggest such a thing could be kept track of. If confined to subluminal technologies, that's even more true. A simple troop deployment, engagement and withdrawal, might easily take several centuries in the relative time of the ones who ordered the action. And it would almost certainly fail. Even striking against a 1500's civilization might well end as a strike against a comparable 2600's civilization - against which the force would be completely harmless.

A lot can happen in a decade. A whole hell of a lot can happen in several centuries.

I suppose it all depends on the purpose of the generation ship.

A practically closed system with biological material producing food, oxygen, and waste filtration should be pretty simple. Algae, small plants, and invertebrates can provide all that quite easily. You will of course have to counter for losing a lot of atmosphere through the hull as well as the hull itself through ablation and impacts. Fuel would probably be the biggest problem (no perpetual motion).

Genetic diversity wouldn't be an issue, as you could bring along plenty of genetic material from the point of origin to eliminate inbreeding.

You could develop something like the matrix - most of the inhabitants could exist solely in compact pods. Spend childhood mostly outside the system - with time in virtual worlds for education and entertainment, but with plenty of physical activity to ensure good health. Good gestation candidates produce offspring when needed, then can be put into a pod. Robotic manipulation by the pod people can conduct most of the work around the ship, so only a tight core where the pods and creche are located needs to be strongly shielded from the worst of the radiation.

Virtual existences would likely help with the psychological problems inherent in being on board while facilitating knowledge and scientific study. This would serve as an intellectual think-tank, vastly reduce the space needed for the crew, greatly improve the efficiency of the nutrition and waste systems... actually you could probably take it a step further and reduce any crewman past physical prime to being brains in jars. With the right interface devices, there need not be any drawback as the crew could experience complete virtual sensory immersion. Keep some sort of proto-blood circulation through the brain tissue and inputs would be minimal while the rest of the corpse could be recycled back through the organic systems. Thus only a quarter of the crew actually needs more than a cubic foot of space (plus life support), minimal caloric/nutritional needs, and minimal power needs. That really cuts down on resource requirements.

The problem is... space is big. You just wont believe how vastly, hugely, mind-boggingly big it is. No matter how efficient you try to get things, thats a staggering feat to get to another star system. The closest star is something like 2.4*10^13 miles away, and that is only a fraction of how far it might be to the actual destination (presumably some interesting planet somewhere). Even if you assume an orion type vessel could achieve a significant velocity (say 0.03c), it might take 3 or 4 centuries to reach its destination. That is a lot of resources you need to take just to survive (even in an incredibly high efficiency system, there will be loss), plus a huge amount of fuel for propulsion.

First step would be to build orbital colonies that can remain independent and work out the kinks in the systems, identify possible problems, and develop better designs before sending such a massive investment into the unknown without any possibility of support. And really... once you have a practically self-sufficient space colony, you're not all that worried about how long its going to take to get there. Just live in a spacefaring society that hangs out in a solar system to replenish supplies every few centuries.

IA practically closed system with biological material producing food, oxygen, and waste filtration should be pretty simple. Algae, small plants, and invertebrates can provide all that quite easily.

Insufficient diversity I fear. Not to mention that an algae atmosphere would stink like hell ;)

Insufficient diversity I fear. Not to mention that an algae atmosphere would stink like hell ;)

Diversity? You can engineer different species of algae or bacteria to produce any vitamin you need and convert minerals into a bioavailable form. A variety of invertebrates can provide any protein structures you want. What more diversity do you need? I threw in small plants because they can process human waste and scrub the air quite efficiently while adding a lot of variety of textures to the diet (flavors are easily added, but texture is more difficult).

Just because you use algae to scrub out the CO2 doesnt mean it has to stink that badly - besides, humans adapt to smells quite readily. The only people who would even think about it would be the very first generation (and even they would stop noticing after a little while) while the rest would never even be aware of any 'smell'.

I suppose it all depends on the purpose of the generation ship.Fuel isn't much of a problem. All that's needed is a bit of initial thrust. After that, Bussard ramjet can both keep the thing going and, assuming space to store fuel, slow it down. Even better, that kind of propulsion can both accelerate and decelerate a vessel very, very quickly, which can simulate gravity. It's simply a matter of designing the vessel for it, pick the desired speed, and then accelerate and decelerate at 1G in a suitable pattern.

Humans are fairly easy to breed. Even a hundred individuals is more than enough. But a few times that is probably needed, both to avoid people cracking left and right, and to ensure there's skilled labour for when people get to where ever it is they're going.

Isolating people in some type of VR is probably not a good idea, but the vessel doesn't need to have any particular design or be suitable for strong gravity, atmospheric pressure and so on. That means it can accommodate people's need for privacy, as well as their need to associate in different environments. It just has to be designed for it.

But there's still the problem of radiation. Even at near-c, it'll likely take a few centuries to get anywhere. In that time, the vessel and everything on it, will be under constant bombardment from space. Short of a 100 feet of ice-coating, there's very little one can do to dodge the effect. And the effect is fairly simple. The radiation breaks down the environment (and of course, kills the crew), massively increasing the rate at which is leaks through the hull and off into cold, dark nothing. When the crew is limited to a non-renewable environment, and a journey measured in decades or centuries, that quickly becomes a killer problem. First the crew dies, then all the other organic life dies, then the atmosphere vanishes, and finally the hull and assorted electronics fall apart. And the trip's only just under way.

I think I mentioned it earlier, but the only solution I've heard proposed, is to haul a small ocean off into space, somehow spin an enormous tube out of it, and make the generation ship inside the tube. But that's a tricky proposal, methinks.

But there’s still the problem of radiation. Even at near-c, it’ll likely take a few centuries to get anywhere. In that time, the vessel and everything on it, will be under constant bombardment from space.
Do you know if modern-day astronauts are in space long enough to be affected by this?

Aren't there problems with sheilding the crews from radiation as well?

There are indeed problems with shielding. Cosmic rays, charged particles traveling at significant fractions of the speed of light, are incredibly penetrating. Even when they strike another atom/molecule/particle, the impact typically produces a host of high energy photons (gamma rays and x-rays) and a further cascade of charged particles. Therefore even stopping the cosmic rays won't protect you as this cascade will penetrate for quite some distance into the absorber.

This is also the problem with developing a vehicle that travels at some significant fraction of the speed of light: now -every- particle encountered is a cosmic ray! Because from your perspective you're stationary, and so every atom/molecule/particle you encounter is now striking your ship with your velocity plus some relativistic correction for its own. Just not a pretty picture.

Diversity? You can engineer different species of algae or bacteria to produce any vitamin you need and convert minerals into a bioavailable form. A variety of invertebrates can provide any protein structures you want. What more diversity do you need? I threw in small plants because they can process human waste and scrub the air quite efficiently while adding a lot of variety of textures to the diet (flavors are easily added, but texture is more difficult).

Variety of food. Variety of crops that can be sown on the destination. Variety to provide a decent and relatively attractive ecosystem - because the many generations of humans will get bored otherwise. Variety in biomes to be certain the whole thing does not break down if something unforeseen happens (e.g. some hithero unknown effect that kills every species of algea) - i.e. overlapping backups.

But true- people would get used to the smell.

Do you know if modern-day astronauts are in space long enough to be affected by this?

No, because they aren't even traveling at 0.005% of the speed of light (we're still -VERY- slow!). The radiation issue for modern astronauts is simply that they have only an incredibly thin shield against any kind of radiation.

With sufficient plate thickness and seperation distance radiation from the charges shouldn't be a problem. Nearly everything that could go wrong with the Nuclear Pulse Rocket was worked out 40 years ago during the first engineering study. The team even built 2 prototypes to see if the ships would just be destroyed by the blasts. The prototypes held together and there was even a video of one of the tests floating around the interwebz a while back. The reason that we don't have cheap, efficient space-travel today is because of the testing ban. If you can't set off nukes then Orion ships become useless. Damn hippies ruined science!
Aye, it's not like killing about 10% of the population through nuclear fallout and sterilising most men either temporarily or permanently, as well as causing masses of cancer every time a rocket of any considerable size is launched, would lead to any long-term problems, right?

Variety of food. Variety of crops that can be sown on the destination. Variety to provide a decent and relatively attractive ecosystem - because the many generations of humans will get bored otherwise. Variety in biomes to be certain the whole thing does not break down if something unforeseen happens (e.g. some hithero unknown effect that kills every species of algea) - i.e. overlapping backups.

But true- people would get used to the smell.

That is assuming that the trip is to attempt to terraform some planet - in which case they can just keep a seed bank rather than having to have every plant actively growing on board.

I just took redundancy of systems for granted when talking about space travel - you never ever have a single point of failure for anything. Though if youre talking about something wiping out all your bacteria cultures or something, it isnt a problem. We can already 'create life' as far as taking all the component chemicals and make the simplest of bacteria - a couple hundred years from now there shouldnt be any problem with creating simple organisms like algae from a DNA record. Even in terrestrial computing we have a triple redundancy rule of thumb - when the entire expedition could be wiped out, i doubt they would have anything less.

There's a much simpler solution to generation ships. Terraform Jupiter's moons. Colonize them. Stick a hugeass fusion rocket in Jupiter which can feed on Jupiter's gases. Launch Jupiter towards target system.

Try to avoid smacking into other planets on arrival.

The fusion rocket will act as an artificial sun, and Jupiter will take its moons with it when it goes on the trip.

Interesting idea, but quite a few problems.

The gravitational force between the sun and Jupiter is roughly 4.13x10^27 Newtons. To even get Jupiter to move away from the sun at all is going to take a force of at least that amount.

Given that, the amount of energy needed to move Jupiter one centimeter with that force is roughly 4.13x10^25 Joules. Now, if you get 100% return for your fusion of hydrogen into helium (which you won't), then Jupiter will have to lose 4.58x10^8 kilograms of mass in moving just that one centimeter (loss of mass that produces the released energy in the fusion reaction).

Now, the force of gravity between Jupiter and Sun is going to decrease as the two move apart, but even getting to the heliopause is going to consume a large percentage of Jupiter's mass and until it gets to that point you're still going to have to burn fuel or fall back into the system.

All of that and I still didn't take into account angular momentum, which you're going to have to expend energy to kill to get away from the sun, or that you might want a higher acceleration than "just enough to get away." Want that higher acceleration? You're going to have to burn more hydrogen. Keep in mind too that you've colonized Jupiter's moons. That loss of mass from your fusion of its hydrogen into helium is going to make it less able to hold onto those moons, so likely you'll have to burn fuel to keep them in orbit and kill their angular momentum or just let them fly off on their own. Even beyond that...Jupiter's not 100% hydrogen which is going to lower your fusion efficiency as well as reducing your effective fuel amount.

Low and behold, I don't think you could get Jupiter out of the solar system, much less to another star, even if you did burn all of its hydrogen in fusion reactions. Welcome to the wonderful world diminishing returns: you have more fuel, but it takes burning more fuel to now move that fuel!

Interesting idea, but quite a few problems.

Low and behold, I don't think you could get Jupiter out of the solar system, much less to another star, even if you did burn all of its hydrogen in fusion reactions. Welcome to the wonderful world diminishing returns: you have more fuel, but it takes burning more fuel to now move that fuel!Heh, yeh. It's probably less impossible to use the planets to build a megastructure around the Sun, and use it's normal emissions to get going. But then.. That's the really, really slow solution.

An ocean with a ship inside and a ramjet stuck on still sounds like the more plausible solution to me. In fact, if there wasn't the tiny problem of finding a spare ocean, getting it into space and making a fucking gigantic tube or sphere out of it, it would be workable. Assuming, of course, that people don't fall apart on the way for some reason.