Date: Mon, 16 Nov 92 05:24:27 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #428 To: Space Digest Readers Precedence: bulk Space Digest Mon, 16 Nov 92 Volume 15 : Issue 428 Today's Topics: COSTAR Hubble's mirror Shuttle computers Town Meeting 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: Mon, 16 Nov 92 00:02:29 EST From: John Roberts Subject: COSTAR -From: henry@zoo.toronto.edu (Henry Spencer) -Subject: Re: COSTAR -Date: 14 Nov 92 23:48:26 GMT -In article roberts@cmr.ncsl.nist.gov (John Roberts) writes: ->There was a replica of COSTAR on display at the World Space Congress. ->I couldn't make head or tail of it... [Detailed description of COSTAR] Thanks for the reply. It appears that my interpretation of the NASA Select video (followup post, that hasn't percolated through yet) was reasonably close. -It looks like a weird plant, with -arms sprouting out in semi-random directions, because the instrument -viewing apertures are in different places on each instrument. (Luckily, -none of the apertures is very large, so small mirrors will suffice.) -All of this, of course, has to be very rigid and capable of very precise -adjustment by remote control. Anything on what degrees of motion can be adjusted? (i.e. swing angle, arm length, tilt, spacing.) John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: 16 Nov 92 03:35:55 GMT From: Greg Hennessy Subject: Hubble's mirror Newsgroups: sci.astro,sci.space Henry Spencer writes: #To the best of my knowledge, the only statement in my posting which is #not a solidly-established fact . . . I was referring to your statment implying that Dr. Jefferys was contributing to the "technological myth of the century." Correcting Dr. Jefferys on matters of the HST is like correcting Dennis Ritchie on matters of C. While certianly a very expensive end to end test would have caught the trouble, assuming that such a test is even possible (which I'm not convinced of given the difficulty), the set of tests that you develop to test a mirror BEFORE you know it has a certian problem is not necessarily the same as the set of tests that you develop AFTER you know it has a problem. PE developed a system of testing that they THOUGHT would be good enough. Unfortunately it was not. At least we can be pretty sure that this blunder won't be repeated. -- -Greg Hennessy, University of Virginia USPS Mail: Astronomy Department, Charlottesville, VA 22903-2475 USA Internet: gsh7w@virginia.edu UUCP: ...!uunet!virginia!gsh7w ------------------------------ Date: Mon, 16 Nov 92 00:07:05 EST From: John Roberts Subject: Shuttle computers -From: henry@zoo.toronto.edu (Henry Spencer) -Subject: Re: What kind of computers are in the shuttle? -Date: 14 Nov 92 23:58:37 GMT -There are also some other little problems, like the fact that the orbiter -computers aren't independent systems -- those five main computers operate -in very close lockstep for fault tolerance. This isn't just a tougher -version of a commercial computer system. Do you recall how tight the lockstep is? I don't believe I've seen anything written on that since before STS-1. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: Mon, 16 Nov 92 00:39:16 EST From: John Roberts Subject: Town Meeting -From: aws@iti.org (Allen W. Sherzer) -Subject: Re: SUMMARY of 1st NASA TOWN MEETING -- Raleigh NC (long) -Date: 14 Nov 92 23:17:44 GMT -In article <1992Nov13.160320.16902@samba.oit.unc.edu> cecil@physics.unc.edu writes: -> What about SSTO? -- too many launch vehicle programs in the works. Some -> must be cancelled. -Did Goldin say this? If so, I'm disapointed. Question: does this reflect a *change* in NASA policy toward DCX? -Surely it's worth the cost of a couple of Shuttle flights to see if -the concept works? Well, *I* think so, but then I'm not part of the budget decision process. As far as manned moon/Mars expeditions are concerned, Goldin doesn't seem to have given up on those permanently - he seems to feel that if the prerequisites can be taken care of (demonstrating realistic cost estimates, the small quick unmanned probes, reduction of launch costs), then the government may again be willing to look in that direction. (My own opinion is that at least small amounts of funding should be maintained so that planning and cooking of new ideas can be continued, both for manned interplanetary activity and for all of the launcher programs. This could be justified as technology development. One thing that could be very useful is to kill the name "SEI" entirely - once it was viewed as a magic word that could be used to secure huge amounts of funding, but now attaching the name SEI to a project proposal is like trying to sell "Rat Poison" brand baby formula.) By the way, this past week George Stephanopoulos told the press that his team is still accepting suggestions and requests, in the form of 30000 letters a day. :-) John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ End of Space Digest Volume 15 : Issue 428 ------------------------------