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Article #345Re: Mars salt ?
From: The Ghost In The Machine
Date: Sat, 28 Apr 2007 04:37
Date: Sat, 28 Apr 2007 04:37
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3790 bytes
In sci.physics, Jeff Findley <jeff.findley@ugs.nojunk.com> wrote on Fri, 27 Apr 2007 13:26:32 -0400 <e56d3$46323246$927a2cda$25726@FUSE.NET>: > > "The Ghost In The Machine" <ewill@sirius.tg00suus7038.net> wrote in message > news:s1i9g4-1f8.ln1@sirius.tg00suus7038.net... >> However, absent some major technological boost to our rocket exhaust >> velocity (chemical rockets have poor performance but lots of thrust), >> it's going to be expensive to get into space no matter what we do. > > I believe this is a flawed assertion. The hard limit on launch costs is the > cost of fuel and oxidizer since that would be your only reoccurring cost for > a reusable launch vehicle. And if you do the math, the cost of fuel and > oxidizer for a LOX/kerosene launch vehicle isn't bad at all. > > Jeff It depends on the rocket performance -- v_e in Tsiolkovski's Rocket Equation: v_f = v_i + v_e * log(M_i/M_f) Unfortunately, because Earth drags us all down, chemical rockets are about the only things that have enough thrust to overcome their own weight for sufficiently long to get into low Earth orbit and beyond. Ion drives have nice high v_e but very low thrust, for example. The best I can do is boil water a la Asimov using a nuclear pile, and such rockets would have to be huge and very high pressure. You probably remember the Cassini mission (which is now happily orbiting Saturn; AFAIK there's no aliens out there complaining about the plutonium canisters whose radioactive decay is used as a power source :-) ). A nuclear reactor would generate even more heat -- and not for the purpose of producing lifting thrust. -- #191, ewill3@earthlink.net "Woman? What woman?" -- Posted via a free Usenet account from http://www.teranews.com
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X-Google-Thread: 107d29,f476068e9b2bf8c8 X-Google-Thread: f74ae,f476068e9b2bf8c8 X-Google-Thread: 10b271,f476068e9b2bf8c8 X-Google-Thread: 102f53,f476068e9b2bf8c8 X-Google-Attributes: gid107d29,gidf74ae,gid10b271,gid102f53,public X-Google-Language: ENGLISH,ASCII-7-bit Path: arc1-ca.pugleaf.net!g2news1.google.com!news1.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!t-online.de!storethat.news.telefonica.de!telefonica.de!nntpserver.com!zeus.nntpserver.com!10.1.1.41.MISMATCH!pfilter-v0.1!not-for-mail Newsgroups: sci.space.history,sci.astro,sci.physics,cam.misc From: The Ghost In The Machine <ewill@sirius.tg00suus7038.net> Subject: Re: Mars salt ? References: <1174182067.660393.98440@n76g2000hsh.googlegroups.com> <W4-dnXg5UN2dN7rbnZ2dnUVZ8tDinZ2d@pipex.net> <1177134456.916981.80370@o5g2000hsb.googlegroups.com> <6q6dnUhcSMUJ2bfbnZ2dnUVZ8tOmnZ2d@pipex.net> <1177259087.103702.106660@p77g2000hsh.googlegroups.com> <Bt-dnYwK2MAICrbbnZ2dnUVZ8tijnZ2d@pipex.net> <1177266455.838067.298530@y80g2000hsf.googlegroups.com> <5JKdnfDYGPhYNrbbnZ2dnUVZ8turnZ2d@pipex.net> <1177269003.625009.282650@d57g2000hsg.googlegroups.com> <2MSdnTdgFe1OKLbbRVnyiwA@pipex.net> <1177338878.138950.312980@y5g2000hsa.googlegroups.com> <ioadnR8YtdQ1bbHbnZ2dnUVZ8vydnZ2d@pipex.net> <3f90g4-uop.ln1@sirius.tg00suus7038.net> <1177443515.293965.88170@n35g2000prd.googlegroups.com> <t833g4-vff.ln1@sirius.tg00suus7038.net> <1177606638.042568.60010@s33g2000prh.googlegroups.com> <ol28g4-kao.ln1@sirius.tg00suus7038.net> <8c6d1$4631f92f$927a2cda$6863@FUSE.NET> <s1i9g4-1f8.ln1@sirius.tg00suus7038.net> <e56d3$46323246$927a2cda$25726@FUSE.NET> X-face: "i;@/WO(?;[KC9sW;wG/4@H[_VFFH4?QHJ#O(?m}7fQMrJ,]0THA'\|e-EPG_>56Mi}_RRhBS'a2}u_7jm)0_+'=$V#E2r4#IQE/d)yMv3_4@hl<)mA&*tDN/ User-Agent: slrn/0.9.8.1 (Linux) Date: Fri, 27 Apr 2007 21:37:46 -0700 Message-ID: <qlvag4-rle.ln1@sirius.tg00suus7038.net> Lines: 42 NNTP-Posting-Date: 28 Apr 2007 04:07:14 GMT X-Complaints-To: abuse@teranews.com