15 July 2007

Generation Seed Ships for Colonising Space

Unless science discovers a workable faster than light drive in the next century or two, it is likely that humans will attempt to launch generation ships to cross the interstellar gulf between star systems. On a generation ship, a voyage between star systems may take several millenia. For the many generations growing up, living, and dying aboard these ships, the destination becomes secondary to the journey itself.

Centauri Dreams blog discusses this issue, using a Michael Anissimov posting as a launch pad:

Noting Marshall Savage’s projection that the asteroid belt could theoretically house 7,500 trillion people if exploited in its entirety (this is drawn from the latter’s The Millennial Project), Anissimov goes on to ponder the motivations for space exploration itself. Here’s one relevant bit:

Why expand into space? For many, the answers are blatantly obvious, but the easiest is that the alternatives are limiting the human freedom to reproduce, or mass murder, both of which are morally unacceptable. Population growth is not inherently antithetical to a love of the environment - in fact, by expanding outwards into the cosmos in all directions, we’ll be able to seed every star system with every species of plant and animal imaginable. The genetic diversity of the embryonic home planet will seem tiny by comparison.

That is a very good point.Our very own solar system possesses resources that would allow humans to build a prolific base of operations for launching into the interstellar spaces. The best way to go beyond the asteroid belt and the Oort/Kuiper regions, is to build a sustainable/expandable infrastructure in those very regions first.

The best raw material for a generation ship is an asteroid or comet. The inertia/mass would be large for initial acceleration out of the system, but the raw materials would be indispensable for the long voyage outward. Tunneling into the interior of the asteroid/comet provides a protected living and working environment. Aeroponics would provide a good method of growing crops. Nuclear energy would be the most logical method of propulsion and energy supply--fusion if available.

Here is more on:

Colony Ships

Interstellar Travel

Space Colonisation

And why the surface of a planet may not be the best place for humans to evolve further.

For more mind expanding thoughts on expanding human existence, check out the latest postings at Accelerating Future and Advanced Nanotechnology blogs. Both Michael and Brian have posted some extraordinarily thoughtful posts recently.

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Anonymous Anonymous said...

The problem with the idea of generation ships taking thousands of years to get to the nearby stars, is that they'll probably arrive there to discover it's already been colonised by humans who left a century or more later on faster ships. It would be like Columbus leaving Spain in 1492 to be passed by 747s along the way and find the Carribean a holiday resort by the time he arrived in 2007.

Worse than that, I suspect the odds of being able to maintain a small group of people in a viable society for thousands of years en route to a new star are pretty small; you're talking about surviving the equivalent of most of the recorded history of the human race with a stable population and no major conflict.

A stable population might be possible if life extension meant there would be very few generations between Earth and landing (or even no births at all), but such a culture would probably have great difficulties suddenly adjusting to breeding far more people after they arrive.

Absent a local catastrophe which forces you to leave this system quickly, you're almost certainly going to be better off waiting until you can use a smaller ship that will get there in a few decades at 5-10% of the speed of light.

Sunday, 15 July, 2007  
Blogger al fin said...

AA, you seem to have given this issue a lot of thought.

I suspect that the type of person who would readily volunteer for a generation ship--knowing they will never see their destination--is someone for whom the journey is more important than the arrival. Centauri-Dreams pointed out in his post that most of the generation ships' populations would probably be so acclimated to living onboard ship that they would probably stay in the target star system only long enough to collect data, and possibly drop off any persons wanting to stay in-system. Then they would go on to the next target system. Perpetual wanderers, as it were, like space traveling gypsies.

As for the stable population, the whole point of traveling inside a partially excavated comet/asteroid is to allow room to expand and plenty of raw material for propellant, building exploratory and landing craft, and energy production. It would be necessary to limit the rate of growth of the population of course. But as mentioned, at every star system anyone who wanted off could elect to colonise a likely looking planet.

If other humans had preceded them, an exchange of genetic material may take place.

Every star system probably has asteroids and/or comets, for branching out into new generation ships.

Like most things it is not clearly good, nor clearly bad. You would certainly want to weigh all your options first, of course, before signing on.

Some would wait for FTL transport, many would choose to hit the void as soon as possible.

Sunday, 15 July, 2007  
Blogger Michael Anissimov said...

Hey, thanks for the shout-outs. I wish you were here in the Bay Area, because me and Brian have gotten together a few times and had meatspace conversations of great interest. Some of them have been filmed and may make an appearance on the Internets later this year.

Monday, 16 July, 2007  
Blogger chuckatmain said...

Why not just render Earth more livable?

Thursday, 19 July, 2007  
Blogger al fin said...

Earth is a large planet, not completely under the control of western democracies. Despots such as Robert Mugabe, Vladimir Putin, the Iranian mullahs, North Korea's Kim, etc. do not care about the Earth. Should they wish to start a nuclear war or otherwise devastate the planet they will do so.

A large asteroid plummeting toward Earth likewise does not care about the Earth. It would destroy the Earth without remorse.

There are any number of existential disasters capable of making the Earth unable to support the billions of humans currently enjoying its planetary abundance.

Consider it the prudence of not placing all of humanity's eggs in one basket.

Friday, 20 July, 2007  

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