On Sat, Nov 28, 2009 at 12:43 AM, Onno Meyer <[email protected]> wrote: > I'm thinking about a sublight interstellar craft with the Vehicles > rules. The optimized fusion rocket allows perhaps 2% of lightspeed, > so trips will take centuries. That leaves cryosleep and generation > ships. The sleeper doesn't translate well into Spaceships, so I'm > looking at a generation ship. > > * Fusion reactors are supposed to last 200 years. I'm assuming that > is from first ignition, not from construction, or I wouldn't have > a chance anyway. Ten reactors can last 2,000 years and roughly 10 > parsec ... > > * Vehicles says nothing about the efficiency of total life support. > If I call it 99.9%, the ship would need provisions for 2 years. > I don't envision actual foodstuffs, more like spare seeds and > fertilizer, but mass is mass. Does that sound reasonable? > > * How much of a population do I need? There might be frozen ova to > help with genetic diversity, but it wouldn't do to have the only > qualified engineer slip and break his neck. There must be some > redundancy. And even if there are hundreds of people, the kids > will grow up weird in that small world. > > * How do I handle spare parts? There must be some manufacturing > capability, call it complete workshops and minifacs from UT, > but they still need materials. > > * What is the mission plan once the ship arrives in a system? I > guess they'll capture an asteroid and begin mining and building > and breeding. Bringing landers and terraforming gear takes too > much mass, so they are only blueprints on file. > > A fraction of the total delta-V should be ample for insystem > purposes.
Check to see if some sort of space sail can be used to improve fuel efficiency; at the very least, a mag-sail should be able to save on fuel by acting as a braking system. The question is if it will save enough fuel to be worth its mass. If you're going for a generation ship, consider the Habitat modules from VX2 (I think). You might even go with a small metallic asteroid reshaped into a hollow cylinder: sure, it's a significant amount of mass; but it's also a wide-open space, which will benefit the colonists. Instead of installing ten fusion reactors to power the ship's systems for 2000 years, just carry additional reactor fuel. It certainly won't mass anywhere near as much as nine additional reactors. GURPS Space gives advice on the minimum population for a start-up colony; your generation fleet (it needn't be one ship, and probably shouldn't be) should probably have a bit more than that. After all, the fleet itself is essentially a colony already. -- Jonathan "Dataweaver" Lang _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
