X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
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From: cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!watserv1!watdragon!watyew!jdnicoll@tut.cis.ohio-state.edu (Brian or James)
Subject: Re: Spacecraft drives and fuel efficiency
I think perhaps Mr. Ryan is incorrect in his statements about energy contents
of high exhaust velocity boosters. It's true that mass ratios go down as
Ve increases, but the energy tied up in getting the reaction mass to Ve goes
up exponentially (E~V*e2). A pure 'photon-drive' style booster would be one
hell of good light show before your eyes ran down your face, and would be a good way to drive a mohole at the same time (My texts are inaccessable right now.
Could someone post the power output of a hundred ton launch vehicle boosting
at 4ish gs propelled by a pure annihilation booster?). Not that anyone advocatedusing these extreme approach, of course.
Whem I said that the detonation of an annhilation energised booster would
be survivable at short ranges, I meant on the order of 1000 meters or so, and
I assumed a launch mass of only a few hundred tonnes using a couple of mg of
antimatter. Mr. Maroney advocates only producing this stuff in space (Lunar
Farside, anyone?). The problem with that is the current lack of well developed
power generating systems in space (OK, there's one *big* fusion generator, but
it's currently hard to get a direct feed cheaply). If you put the am source
on Earth, you can use the powergeneration systems in place now. If prudence
dictates a remote location like Farside, then I suspect that antimatter is
unlikely to contribute anything useful for a long time.