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Date: Mon, 16 Nov 92 05:24:27
From: Space Digest maintainer <digests@isu.isunet.edu>
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
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----------------------------------------------------------------------
Date: Mon, 16 Nov 92 00:02:29 EST
From: John Roberts <roberts@cmr.ncsl.nist.gov>
Subject: COSTAR
-From: henry@zoo.toronto.edu (Henry Spencer)
-Subject: Re: COSTAR
-Date: 14 Nov 92 23:48:26 GMT
-In article <Bxor9M.Jq6.1@cs.cmu.edu> 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 <gsh7w@fermi.clas.Virginia.EDU>
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 <roberts@cmr.ncsl.nist.gov>
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 <roberts@cmr.ncsl.nist.gov>
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
------------------------------