On Wed, 2011-09-28 at 19:36 +0200, Onno Meyer wrote: > Hello everybody, > > I've been thinking about asteroid bases, comet ships, and the > like. Does this make sense to you? > > * Vehicles has no rules for asteroid hulls, but both Traveller > and Transhuman Space do. When it comes to structural design > rules, Traveller is closer to generic GURPS than THS. > > * A rock with one mile diameter is roughly 75,000,000,000 cf, > or 150,000,000 Traveller dtons. That means 18,750,000,000 > stons according to the GT rules. > > * I'm assuming that a delta-V of 25 mps is good for insystem > flights in a decent timeframe. > > * With a mass driver engine from VXi, which has Isp 720, the > required fuel percentage is about 99.6%.
Realistic studies of getting comets and asteroids to Earth orbit involve a lot more than brute force thrust. What you want is to find an asteroid that's already going your way, mostly. Then you use small amounts of force (small relative to the rock anyway) to adjust its orbit to take advantage of gravity forces like Jupiter and Saturn, and on the incoming side you might sling it around Mars, Venus, even Earth and the Moon in order to get the orbit and the final speed to the correct range. I think the only way to have an asteroid ship that you can fly where you like within a few months is to have a reactionless drive and fusion or antimatter power. Or ... John Ringo has a pseudo-realistic asteroid ship in his Troy Rising series and it gets around through the use of fusion bombs (aka "fusion impulse drive"). I'm not sure how you'd figure the thrust per bomb. Take the megatonnage, divide by how much of the radiation impacts on the asteroid's "push plate" surface. Some of the surface will overheat and vaporize, adding reaction thrust while other thrust will be only radiation presssure. You'd need a *lot* of bombs, so you'd better have some sort of asteroid mining industry extracting fissile elements and some kind of autofactory. -- Knowledge Is Power Power Corrupts Study Hard Be Evil _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
