Aucbvax.6267 fa.space utcsrgv!utzoo!decvax!ucbvax!space Tue Feb 23 03:58:25 1982 SPACE Digest V2 #113 >From OTA@S1-A Tue Feb 23 03:53:57 1982 SPACE Digest Volume 2 : Issue 113 Today's Topics: Recycling Titans More Politics & Marginal Costs "30-year-old Titans... oops!" "Man's guts were not made for orbital mechanics..." SPS tidal stabilization Re: twisting of orbital platforms Twisting of orbital platforms SPS tidal stabilization launching old titans Tidal stabilization ---------------------------------------------------------------------- Date: 22 Feb 1982 0950-CST From: Clyde Hoover Subject: Recycling Titans To: space at MIT-MC Unless you use the silos the Titans are in now, you have the cost of emptying them of propellant (Titan propellants are noxious liquids), hauling them out to KSC (where you can use LC 43) to launch them. This would not be cheap. On the other hand, you can't launch them from where they are now because the first stages would drop on somebody (unless you shot them all into near-polar orbit, even then Candians probably would not like to have 10 ton+ hunks of junk falling from 30 miles up on to their territory). Remember, the Titan silos were placed for a one-shot, over the pole trajectory to the USSR, and if you get to the point of lighting those babies it really doesn't matter if a crashing first stage kills some caribou. Nice idea, though - using the old beasts would save some hardware purchase costs, though the launch costs would not be appreicably less than that of the Titan III (a favorite of the Air Force for launching recon sattellites and used for Viking and Voyager). ------- ------------------------------ Date: 22 Feb 1982 0813-PST Sender: WARD at USC-ISIF Subject: More Politics & Marginal Costs From: Craig E. Ward To: Space at MIT-MC Cc: Ward at USC-ISIF, Pourne at MIT-MC, TCS at ECL, Riedel at ECL, Katz at USC-ISIF, REM at MIT-MC Message-ID: <[USC-ISIF]22-FEB-82 08:13:13.WARD> I don't want to say "I told you so", but I told you so. In this Saturday's (Feb. 20) Santa Ana Register an article appeared with the headline "Space shuttle: an economic 'monstrosity'? $2-billion- a-year savings seen if project is scrapped". It was written by a Peter Larson of the Orlando Sentinel Star. One of the article's main points is that James Van Allen says so in his Science article. The reporter also interviewed a NASA spokesman named Charles Redmond who is quoted as saying NASA isn't sure about the Shuttle paying off. ("There's a lot of corridor talk..."). I wonder about this. Has anyone ever tried to figure out what the marginal cost of a shuttle launch is? (The marginal cost of something is the cost of doing or making one more of it). In my view, the money spent on developing the shuttle can not be used in figuring the marginal cost. That money is a sunk cost and is gone. We can only look at future expenses and returns. The Shuttle is here and we would be losing everything to drop it now. Also, it would seem to me that the marginal cost of throw-aways will be much greater because you have to keep building new ones. Anyone have figures? Craig P.S. It may also be worthy of note that the AP article below Larson's was headlined "Shuttle test troubled, but called 'success'". It reported some of the problems during Friday's test run. The article itself was not bad, but that headline makes it sound as if NASA is trying to hide something. Do we also have a problem with press coverage? ------------------------------ Date: 22 Feb 1982 08:40 PST From: Ciccarelli at PARC-MAXC Subject: "30-year-old Titans... oops!" To: SPACE at MIT-MC Oops! Somehow my mind transmuted Jerry Pournelle's comment about "30- year- old PROPULSION TECHNOLOGY" (SPACE V2 #108) ...into... "30-year-old Titans". A quick subtraction puts "30 years ago" as 1952, which may be valid for the technology, but not for the missile... (Apologies...) /John ------------------------------ Date: 22 Feb 1982 08:51 PST From: Ciccarelli at PARC-MAXC Subject: "Man's guts were not made for orbital mechanics..." To: SPACE at MIT-MC cc: Ciccarelli Methinks you speak of dirt-siders, spasebaw! The first generation that is born and raised in orbit will have no problem with the everyday mechanics... Playing catch, that parabolic pastime for Grounders, might be one of the ways a kid will learn physics "up there". Possibly, someone raised in "free fall" would just develop "orbital chauvinism" with regard to mechanics, just as we surface-dwellers have our "planetary chauvinism". /John ------------------------------ Date: 22 Feb 1982 10:28 PST From: Wedekind.ES at PARC-MAXC Subject: SPS tidal stabilization To: King at KESTREL, REM at mit-mc cc: SPACE@MIT-MC, Wedekind.es I missed some things here. Could someone recap and tell me precisely the problem you are trying to solve? Does it arise from the fact that an SPS would be so big that the gravity gradient becomes relevant? Jerry ------------------------------ Date: 22 February 1982 1226-cst From: Bill Vaughan Subject: Re: twisting of orbital platforms To: REM at MIT-MC Cc: space at mc yup, weight is just to increase tidal forces. Moment arm is simply distance between upper & lower attachment points, which can be several feet; or distance between single attachment point and bird's center of mass when only one pendulum is used. My recollection (possibly faulty) says the cables were *quite* long (several hundred meters) and that it took quite a few orbits before everything settled down nicely. I notice that comsats don't seem to use gravity-gradient stabilization so maybe it turned out to be a failure practically. The results are probably in some NASA tech brief somewhere but I don't want to hunt through NTIS for it. ------------------------------ From: CARLF@MIT-AI Date: 02/22/82 13:40:34 Subject: Twisting of orbital platforms CARLF@MIT-AI 02/22/82 13:40:34 Re: Twisting of orbital platforms To: CARLF at MIT-AI, REM at MIT-MC CC: SPACE at MIT-MC Everybody seems to be talking about putting weights on the end of ropes. My idea is to get rid of the weight on the end by replacing it with more rope. I figured this out recursively by noticing that a weight could be replaced by a rope with a smaller weight on the end, and then that weight could be replaced by more rope and an even smaller weight, and so on. This can be very economical, since moment of inertia goes as the square of the distance while tidal acceleration is proportional to distance. I never meant that a rope alone could be a stabilizing device. -- Carl ------------------------------ Date: Monday, 22 February 1982 13:18-PST From: KING at KESTREL To: Wedekind.ES at PARC-MAXC cc: REM at mit-mc, SPACE at MIT-MC, King at KESTREL Subject: SPS tidal stabilization Yes. That's exactly the problem. You have two extended parts to an SPS: the microwave antenna (always more-or-less perpendicular to a line from it through the Earth's center) and the solar collector (varying orientations). The (much larger) solar collector is usually not in a stable position and the position of the (much heavier but smaller) antenna is always metastable. Dick ------------------------------ Date: 22 February 1982 1533-cst From: Bill Vaughan Subject: launching old titans To: space at mc Gee, maybe we *should* launch them directly from the silos. I mean, most everybody in Tucson wants to get rid of them, plus the L-5 society sort of lives there, so we could combine the whole thing -- put together a nice big cheering section for the launch, led by Mo Udall of course; give the southwesterners a chance to see a spaceship go up without having to pay airfare to Canaveral; incidentally destroy the silos so they can't put Minutemen in them (nobody araund Tucson wants that to happen anyway) and - at least temporarily - take the "smog capital of Arizona" title away from Phoenix (*my* hometown)! ------------------------------ Date: 22 Feb 1982 1413-PST From: Ted Anderson Subject: Tidal stabilization To: space at MIT-MC I would like to suggest that since someone who is presumably an expert on the subject has studies the problem of tidal stabilization of satellites we should check with that source. Bill Vaughan suggest that a NASA technical brief exists on the subject, perhaps someone should look up that paper and report back to the digest. As some people have suggested the problem is quite complex. In particular the SPS itself needs to point to the sun, not the earth. The microwave transmitting antenna needs to point to the earth, so these two systems need to be connected by a heavy power cable but decoupled enough to allow them to point in different directions. Clearly this is a system that is much too complicated to be designed over a once-a-day general distribution digest. Ted Anderson ------------------------------ End of SPACE Digest ******************* ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.