NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/sci/space/10813

Text File | 1992-07-26 | 1.9 KB | 40 lines

Newsgroups: sci.space
Path: sparky!uunet!usc!cs.utexas.edu!torn!watserv1!watdragon.uwaterloo.ca!watyew!jdnicoll
From: [e-mail] (James Davis Nicoll)
Subject: Re: Antimatter (was propulsion questions)
Message-ID: <[e-mail]>
Sender: [e-mail] (USENET News System)
Organization: University of Waterloo
References: <[e-mail]> <[e-mail]> <[e-mail]> <[e-mail]>
Date: Sun, 26 Jul 1992 23:26:23 GMT
Lines: 28

In article <[e-mail]> [e-mail] writes:
>[e-mail] (James Davis Nicoll) writes:
>>    Given that one can mix the antimatter-reaction mass ratio to get
>>the Vexhaust one wants, the dangers of standing in the vicinity of the
>>exhaust of an antimatter powered ship could be *identical* to that of
>>standing inthe vicinity of a conventional ship.

>Actually there is one piece of information missing here. In a conventional
>rocket most of the exhaust is being used to push more fuel closer to orbit.
>In an antimatter rocket, you have a much higher payload/fuel ratio, so for
>the same payload, there will be much less exhaust.

    Odds are the antimatter will be the expensive component of the
reaction-mass/'fuel' mix, and so the am-reaction-mass ratio will be such
that the am is used as efficiently as possible. The mass ratio is smallest
if there is a 50% am, 50% matter mix, but that uses much more am then
a mixture of am/m which is mostly matter. I would bet the population of
Gary, Indiana that if antimatter energised propulsion systems are used
from Earth's surface to reach orbit, the exhaust velocity  will be in the
10 km/s range, rather than close to C.

    Also, 'pure' photon drives tend to produce oodles of nasty
hard radiation which could very well fall outside the allowable ranges
of todday's litigation prone society, plus they suck up power like a
mad fiend.

                            James Nicoll