Date: Thu, 31 Dec 92 05:31:08 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #618 To: Space Digest Readers Precedence: bulk Space Digest Thu, 31 Dec 92 Volume 15 : Issue 618 Today's Topics: Aluminum as rocket fuel? averting doom (2 msgs) DC vs Shuttle capabilities fast-track failures Galileo's high-gain antenna still stuck SSTO vs 2 stage Stupid Shut Cost arguements (was Re: Terminal Velocity Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: Thu, 31 Dec 1992 07:38:24 GMT From: Nick Janow Subject: Aluminum as rocket fuel? Newsgroups: sci.space Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) writes: > Using molten aluminum will give a higher Isp than aluminum metal. Major > problems will be pumping, and how to keep the aluminum from freezing in > pipes and injectors when the motor is shut off. Pumping is simple, since aluminum is highly conductive. Just use electromagnetic fields to thrust it through a pipe. There's no moving parts to worry about. I think this is being used in sodium reactor research, so it isn't an untested technology. Keeping the aluminum molten should be easy too...for a rocket that only operates in a vacuum. Since the main reason to use aluminum/oxygen is that it is easily available from the moon, that's not a bad limitation. Pipes and tanks could be polished on the outside to reduce radiation loss, and structural supports could be made of insulating materials, and heated if necessary. If the tanks and pipes were non-conductive (perhaps fibre reinforced ceramics, inductive heating could heat the aluminum directly. Actually, there's not need to get fancy: inductively heat the pipe and tank walls, and heat the aluminum by conduction. Of course, simple resistance heating might be simpler and more efficient. It sounds like a great design for a lunar "space truck", for a future lunar colony. :) Now, what about the nozzle problems.... -- Nick_Janow@mindlink.bc.ca ------------------------------ Date: 31 Dec 92 08:14:14 GMT From: Lamont Granquist Subject: averting doom Newsgroups: sci.astro,sci.space,sci.physics,sci.environment Hmmmm... In my ASTR class, we did a rough calculation that showed that the radius of the Sun would be quite a bit over one AU after it hits the giant branch. If correct, I don't see how mirrors would help us out. Also, according to the ASTR class, the Sun isn't going to explode -- it won't be hot enough to fuse silicon, and instead it will shed it outer envelope and turn into a white dwarf. -- Lamont Granquist lamontg@u.washington.edu "When dogma enters the brain, all intellectual activity ceases." -- Robert Anton Wilson ------------------------------ Date: 31 Dec 92 01:00:57 From: John McCarthy Subject: averting doom Newsgroups: sci.astro,sci.space,sci.physics,sci.environment In article <1hua4mINN64f@shelley.u.washington.edu> lamontg@stein.u.washington.edu (Lamont Granquist) writes: Xref: CSD-NewsHost.Stanford.EDU sci.astro:30048 sci.space:53377 sci.physics:44679 sci.environment:27028 Path: CSD-NewsHost.Stanford.EDU!stanford.edu!agate!usenet.ins.cwru.edu!gatech!destroyer!cs.ubc.ca!uw-beaver!news.u.washington.edu!stein.u.washington.edu!lamontg From: lamontg@stein.u.washington.edu (Lamont Granquist) Newsgroups: sci.astro,sci.space,sci.physics,sci.environment Date: 31 Dec 1992 08:14:14 GMT Organization: 'Operation: Mindcrime' Lines: 11 References: NNTP-Posting-Host: stein.u.washington.edu Hmmmm... In my ASTR class, we did a rough calculation that showed that the radius of the Sun would be quite a bit over one AU after it hits the giant branch. If correct, I don't see how mirrors would help us out. Also, according to the ASTR class, the Sun isn't going to explode -- it won't be hot enough to fuse silicon, and instead it will shed it outer envelope and turn into a white dwarf. -- Lamont Granquist lamontg@u.washington.edu "When dogma enters the brain, all intellectual activity ceases." -- Robert Anton Wilson How far away would the earth have to be in order to be comfortable? How luminous would the sun be in its giant stage? -- John McCarthy, Computer Science Department, Stanford, CA 94305 * He who refuses to do arithmetic is doomed to talk nonsense. ------------------------------ Date: 31 Dec 92 08:01:40 GMT From: "Simon E. Booth" Subject: DC vs Shuttle capabilities Newsgroups: sci.space Don't flame me for this, but could someone please tell me if any of my post ever made it into this newsgroup. It don't know if they got posted and I somehow missed the responses or they just got lost. I never even saw the original messages I posted. Simon ------------------------------ Date: 30 Dec 92 12:06:56 EDT From: Ethan Dicks Subject: fast-track failures Newsgroups: sci.space Shari L Brooks (bafta@cats.ucsc.edu) wrote: : : In article <1992Dec29.164256.18889@murdoch.acc.Virginia.EDU> : rbw3q@rayleigh.mech.Virginia.EDU (Brad Whitehurst) writes: : : > By the time you also pay for FICA, pension, benefits, and : >overhead, a $50,000 engineer can easily cost a company double his base : >pay! Don't forget state payroll taxes (if your state has one - paid by the employer, not the employee) and workman's-compensation (also paid by the company). Other figures in he cost can include the rent/lease payments for the office and the property taxes on the toys that the engineer gets to play with all day. These are ongoing costs, not one time costs like paying for a desk or workstation (unless your organization rents/leases those as well). : Wow, your lab pays for FICA? I'm impressed. It takes up about a third : of *my* salary, when combined with income taxes. Right out of my pay. : I was under the impression it came out of everyone's pay, that that was : the idea behind "Social Security". FICA payments come from employee "contributions" and from matching contributions from the employer. "Self Employment Tax" is FICA, only you pay *both* parts. Take what ever you are paying (~7%-9%, I forget exactly what) and add in an equal amount from your employer. Now kiss it goodbye, because anyone under 50 ain't gonna see it come back :-( -ethan ------------------------------ Date: 31 Dec 92 07:14:08 GMT From: "Marc N. Barrett" Subject: Galileo's high-gain antenna still stuck Newsgroups: sci.space In article <1992Dec30.223543.23648@news.arc.nasa.gov> baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes: > Yesterday, December 29, after approximately 20 hours of >warming in sunlight, the antenna-deploy motors were turned on to >"wind up" the system and then pulsed to "hammer" it in an effort >to free the stuck ribs of Galileo's high-gain antenna. The >procedures began at 6:55 a.m. PST and continued until 2:48 a.m. >PST this morning, December 30. A total of 2160 pulses were >executed by the motors during this period. The stuck ribs were >apparently not freed. This morning the spacecraft was returned >from the warming attitude to the normal cruise mode. Well, what now? What else is being planned to free the antenna? And is it expected to work? --- | Marc Barrett -MB- | email: barrett@iastate.edu -------------------------------------------------- ------------------------------ Date: 31 Dec 92 04:32:07 GMT From: Henry Spencer Subject: SSTO vs 2 stage Newsgroups: sci.space In article <19045@mindlink.bc.ca> Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) writes: >> Advances in technology, perhaps, but hardly recent advances. The old >> Saturn S-IVB stage could've been turned into a SSTO launcher... > > This somewhat confuses the issue, in that it tends to imply that the >technology necessary to build a DC-1 was available a generation ago. The >S-IVB derivative would be a ***non-reusable*** SSTO... No, some of the S-IVB-based SSTO proposals were reusable. I don't know how well they would have worked, and I don't know that I'd plan a spaceline based on them without waiting a while to see how reusable they really were, but on paper it was feasible. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 31 Dec 92 04:38:17 GMT From: Brian Stuart Thorn Subject: Stupid Shut Cost arguements (was Re: Terminal Velocity Newsgroups: sci.space >>Doing that would cost more then they are worth. It would be cheaper to >>build new ones and launch them commercially. >> >Can you show that was also true for SMM? Part of the MMS on UARS is from SMM, >having been brought back after a successfull mission, after earlier being >repaired in orbit. SMM isn't planning to reuse itself, and neither UARS nor >GRO may be either, but there has already been cost savings on UARS due to the >return of SMM. Only the shuttle (product of politics more than NASA's >technical or mangement expertise IMHO) could repair SMM, and only the shuttle >could bring it back. > >------------------------------------------------------------------------------ >Bob Koehler Did I miss something here? SMM is the Solar Maximum Mission, correct? It was not returned to earth, only repaired in orbit. It burned up in 1990, I think. -Brian ------------------------------------------------------------------------- Brian S. Thorn "If ignorance is bliss, BrianT@cup.portal.com this must be heaven." -Diane Chambers, "Cheers" ------------------------------------------------------------------------- ------------------------------ End of Space Digest Volume 15 : Issue 618 ------------------------------