Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V12_0/V12_011.ZIP/V12_011

Internet Message Format | 1991-07-08 | 18KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/MaYM6kK00VcJE8:05H>;
          Wed,  4 Jul 1990 01:42:09 -0400 (EDT)
Message-ID: <[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Wed,  4 Jul 1990 01:41:37 -0400 (EDT)
Subject: SPACE Digest V12 #11

SPACE Digest                                      Volume 12 : Issue 11

Today's Topics:
            Re: How to fix the HST
          Re: Reflections on Hubble and NASA
           Looking for a list of star names
                Nasa's budget
         Re: Aim For The Moon - model rocket contest
               realities of testing HST
          Hubble 2nd Generation Instruments
            Re: How to fix the HST
             Help with GMS images
   Inaccurate quotes (was: Re: More on NASA 91 Appropriation Vote)
           Re: What Spherical Aberration is
        Re: A report on Giotto's earth swingby
          Re: Reflections on Hubble and NASA

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription notices,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

----------------------------------------------------------------------

Date: 3 Jul 90 08:22:18 GMT
From: zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!sirius.ucs.adelaide.edu.au!cs.ua.oz.au![e-mail]  (Francis Vaughan)
Subject: Re: How to fix the HST

In article <[e-mail]>, [e-mail]
(lawrence.m.geary) writes:
|>In article <[e-mail]> [e-mail]
(Francis Vaughan) writes:
|>>
|>>Build a robotic installation machine. The machine is latched to
|>
|>Minor problem: No one one earth knows how to do this yet, and it's unlikely
|>that anyone will have one ready by 1993.

I didn't mean some sort of AI, super amazing, all singing all dancing thing.
Just a simple mechanical device that performs one and only one carefully
designed and rehersed action. Move the corrector down the tube, swing under
the baffle and then pull back into place.


|>The idea of putting individual correctors on each instrument is better
|>because the separate correctors can be optimized for the axial or off axis
|>position of each instrument. A single, big corrector would probably ease
|>problems with some of the instruments while making things worse for others
|>off the optical axis.

I'm not entierly convinced. I don't know enough about optics to really know.
Other problems would be choice of material. It would need to be transparent
to all of the wavelengths in use in all of the instrumentation. That rules
out most glasses. Makes it difficult to make a multi-element design with
different refractive indexes too.

|>Two other problems with individual correctors, though. A) They'll have
|>to replace ALL the instruments. I haven't heard that they are actually
|>considering that, only the WFPC. B) You've got to put the new instruments
|>back into their slots *just right* or they will be out of alignment.

Exactly why I liked the idea of a single corrector. It is also (I think)
a relativle simple fix from a technology point of view. No new technology
would be needed, it should be a straight-forward design job.
Also it may be possible to do something about the oscillations in the
solar panels at the same time. Probably not cure but make it easier for the
guidance system to cope.


                        Francis Vaughan

------------------------------

Date: 3 Jul 90 08:16:06 GMT
From: mcsun!ukc!axion!axion.bt.co.uk![e-mail]  (alan pengelly)
Subject: Re: Reflections on Hubble and NASA


 Okay a mistake has been made, but it is worth remembering
that HST is a novel concept, completely different to anything
that has been done before. That good PR pictures will not
be available for a while is a short term inconvenience. I believe
when the programme is finished it will be viewed as a success.
 Keep at it NASA.

------------------------------

Date: 3 Jul 90 18:14:38 GMT
From: agate!shelby!neon![e-mail]  (Peter Commons)
Subject: Looking for a list of star names

I'm looking for a database of a couple hundred star names (e.g. Sirius, Altair,
Deneb, ...) for use as part of a Macintosh application. If anybody has
something of this sort online (in any form) it would be greatly appreciated.
Please respond by email.



--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|
|   Peter Commons            "Zut, alors! I have meesed one!!!"    |
|   [e-mail]                              |
|   Computer Science Department, Stanford University                  |

------------------------------

Date: 3 Jul 90 19:38:59 GMT
From: thorin!grover![e-mail]  (David Becker)
Subject: Nasa's budget

In article <[e-mail]> [e-mail] writes:
>
>News flash:  shuttle fleet grounded due to design error on h2 pump system
>News flash:  Hubble useless (almost) due to lack of testing on ground
>
>[Congress] will seize this as a chance to lay waste to the entire
>U.S. space effort for the rest of the decade.

Hmmm,  looks like anti-space may become a popular political position.
From the evening the news, the masses, and their representitives,
hear 'Shuttle grounded' and 'Hubble useless'.

How would NASA fare if Congress dropped NASA's Big Space items
(ie. shuttle and Freedom)?  Or cut flights to 1 or 2 a year (that is if
the hardware doesn't force that anyway).

Such trimming may not be as far fetched as it sounds since the shuttle is no
longer relied on by DoD for snoop sats, the deficit is lingering and
space is no longer a guaranteed American-Pride vote getter.  Congress
critters will be aware from now on that space can humiliate them just as
well.

Could cutting the Shuttle and cancelling Freedom actually help space
explotation?  Perhaps forcing NASA to make do with a much smaller
allowance will stimulate the cost-effective launchers that all us
netters are dying for.  Or would the red tape survive as hardware is cut?

David Becker        Gotta love a machine that hangs on
[e-mail]        your every word.

------------------------------

Date: 4 Jul 90 04:00:17 GMT
From: bacchus.pa.dec.com!shlump.nac.dec.com!alien.enet.dec.com![e-mail]
Subject: Re: Aim For The Moon - model rocket contest


>In article <[e-mail]>, [e-mail] (John DuBois) writes...
>>In article <[e-mail]> [e-mail] (Vincent Cate) writes:
>>+PS  Has anyone calculated what a space shuttle solid rocket booster is on
>>+    the "model" rocket scale?  Seems like it will be something like 100 "Z"s
>>+    but I don't have the data for the SRBs.
>>
>>     I worked it out once; as I recall they're close to ZZ's.
>>
>>    John DuBois

The following calculations are based on lift off thrust, since that's the data
I've got. Actual milage may vary, but bear in mind that a factor of two is only
one letter off.

       11,800,000 Newtons thrust
      x           132 Second burn
    -------------
    1,557,600,000 Newton-seconds total impulse
      /         1,280 Newton-seconds (size of J engine for reference)
    -------------
            1,216,875 Times J engine
    Log(2)         20.xx (20-21 steps beyond J engine)

    Puts the SRB at the low end of EE, if the scale goes:

    A B C ... Y Z AA BB CC ...

                            -Brian

------------------------------

Date: 3 Jul 90 16:00:07 GMT
From: mnetor!utzoo![e-mail]  (Henry Spencer)
Subject: realities of testing HST

In article <[e-mail]> [e-mail] (Kim DeVaughn) writes:
>I usually agree with most everything you say Henry, but I have to differ on
>this issue.  When developing anything as sophisticated and unique as the
>HST, one *must* count on good ol' Murphy lurking around *every* corner.  And
>plan accordingly...

"Now, let me get this straight, Dr. HSTfella.  You propose to spend seventy-
five million dollars of the *taxpayers' money* on testing this telescope
against the possibility of what you call `gross errors'.  You've told us
that such errors would occur only as a result of a major error or serious
negligence by your contractors.  Can you please tell us why you awarded a
contract for several hundred million dollars to a contractor that you now
feel you cannot trust?"

Of course it's a good thing to be paranoid.  The trouble is, it says in the
book that this sort of thing can't happen, and when it says that in the
book, people tend to be a wee bit unhappy about spending large amounts of
money checking for the possibility.  Too many people in this group are
burning NASA in effigy for making a mistake they could easily have made
themselves, had they been working under the same constraints.  Hindsight
is always 20-20.
--
"Either NFS must be scrapped or NFS    | Henry Spencer at U of Toronto Zoology
must be changed."  -John K. Ousterhout |  [e-mail]   utzoo!henry

------------------------------

Date: 3 Jul 90 18:31:02 GMT
From: frooz![e-mail]  (Steve Willner, OIR)
Subject: Hubble 2nd Generation Instruments

In article <[e-mail]>, I was wrong about the acronyms for the
second generation instruments.  There are three instruments:

WF/PC2: imager to replace Wide Field/Planetary Camera.
NICMOS: infrared imager and spectrometer, cutoff wavelength 2.5 micron.
        (replacing some instrument not yet decided, but not WF/PC)
STIS  : spectrometer to replace (probably) Faint Object Spectrograph.
        (My understanding is that STIS duplicates most functions of High
        Resolution Spectrograph too, but I may be wrong.  STIS can fit
        in any instrument bay except the one occupied by WF/PC.)

WF/PC2 can compensate for the spherical aberration with a trivial
change.  NICMOS can compensate, but the changes look more complicated.
STIS will probably have to add new optical components.

Thanks to Bill Jefferys for setting me straight.
-------------------------------------------------------------------------
Steve Willner            Phone [phone]         Bitnet:   willner@cfa
Cambridge, MA 02138 USA                 Internet: [e-mail]

------------------------------

Date: 4 Jul 90 02:57:05 GMT
From: network.ucsd.edu!celit![e-mail]  (Dave Smith)
Subject: Re: How to fix the HST

The Hubble mishap is not so much a really stupid mistake as a flaw in the
whole procedure for building and deploying space-based devices.  There are
always problems that will slip through testing.  No testing procedure will
ever find all flaws and the procedures we use here on Earth reflect that.
Deployment of a complicated device has to be an iterative process where
you find and fix flaws.  The whole Hubble problem would be a non-issue
if we had a real presence in space and could just grind a new mirror
and send an astronaut over to pop it in ("just" - I know the mirrors
took forever to grind and they're not designed to be replaced on orbit).

We've probably wasted more money over the years on ridiculous amounts
of ground testing, devices which have been launched only to have some
fatal flaw and the duplication of effort put into each device (does each
device really need it's own orbital insertion computers, engines, etc?)
then we would have to build a real space program.  The reason the
space program doesn't work well is because the approach it tries to take,
of constructing perfect devices that work flawlessly the first time and
therefore will not need fixing, does not fit with the way that humans
work.  That this approach has worked at all is a real testament to the
engineers who put these things together.

--
David L. Smith
FPS Computing, San Diego
ucsd!celerity!dave or [e-mail]
***QUOTE CENSORED BY ORDER OF REV. MOM***

------------------------------

Date: 3 Jul 90 02:45:21 GMT
From: ccncsu!typhoon.atmos.colostate.edu![e-mail]  (Bill Thorson)
Subject: Help with GMS images

I am using some GMS satelite images and am having trouble decoding
the time values.  They encode the time as a floating point value
for both image time and the epoch time for the orbital elements.

The problem is that for an image in 1986 and about the 178th day
the time fields have a value such as 46605.98125432.  I don't know
how to interpret this value.  Someone suggested that it is probably
daynumber.partoftheday.  They also suggested that it may be the
number of day in something like 'astrological' time.

Can anyone give me an idea as the what this time field is and
pointers to algorithms/procedures to decode them?


#!/bin/sh
#-----------------------------------------------------------------------#
echo Bill Thorson                   [e-mail]
echo Dept of Atmospheric Science    [phone]
echo Colorado State University
echo Ft. Collins,  CO  80523        Cray||Sun||Amiga -- I can't decide?
#-----------------------------------------------------------------------#

------------------------------

Date: 3 Jul 90 09:26:56 GMT
From: agate!agate![e-mail]  (William Baxter)
Subject: Inaccurate quotes (was: Re: More on NASA 91 Appropriation Vote)


In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:

>[e-mail] (William Baxter) writes:

>>[Andrew Cutler agrees with me that SEI a waste of money based on the
>>90 day report]

>                                 Why did he
>tell me in a phone conversation (roughly): "At least they are doing it
>[SEI] right this time and taking a few years to study it and not just
>jump in".?

I asked Andy about this.  He says he never made any such statement to
you or to anyone else.  In fact, he said that he has not discussed SEI
with you at all.  You really should quote people accurately.  If you
can't remember who said what, then check with them first.
Misrepresenting Andy's position in order to support your argument
ultimately undermines your own credibility.

Tim Kyger, whose name is commonly associated with your own in this
forum, also thinks that SEI is a waste of money.  He calls it the "Staff
Expansion Initiative."

--
William Baxter

ARPA: web@{garnet,brahms,math}.Berkeley.EDU
UUCP: {sun,dual,decwrl,decvax,hplabs,...}!ucbvax!garnet!web

------------------------------

Date: 3 Jul 90 16:53:05 GMT
From: mnetor!utzoo![e-mail]  (Henry Spencer)
Subject: Re: What Spherical Aberration is

In article <[e-mail]> [e-mail] (Mike McManus) writes:
>So am I missing something?  Assuming that (1) and (2) are known, what's the
>problem with post-processing of images?

The problem is that messed-up optics may just rearrange information, or
they may actually lose information.  For example, if the optics somehow
were to focus all incoming light onto a single pixel in your camera, no
amount of post-processing could ever recover a useful image from that
one bright dot.  In practice it's not that bad, but there are usually
limits on how much of the mess can be post-processed out, especially
when you don't know what the image is supposed to look like and you're
working at the limits of the hardware.
--
"Either NFS must be scrapped or NFS    | Henry Spencer at U of Toronto Zoology
must be changed."  -John K. Ousterhout |  [e-mail]   utzoo!henry

------------------------------

Date: 3 Jul 90 18:37:16 GMT
From: ksr![e-mail]  (Chris Jones)
Subject: Re: A report on Giotto's earth swingby

In article <[e-mail]>, p515dfi@mpirbn (Daniel Fischer) writes:
>It was an absolute first in space history: a spacecraft returning to earth from
>the depths of the solar system, to receive a gravity assist for a new job. On
>2 July 1990 at 10:01:18 Universal Time, precisely five years after its launch,
>the European Giotto spacecraft approached earth to 22730 km over Australia,
>raced past earth in a wide hyperbola with a speed of 6.3 kilometers per second,
>and changed its orbit from one inside earth's to one outside - to meet comet
>Grigg-Skjellerup on 10 Juli 1992 at 15:30 Universal Time +/- a few minutes.

I suppose it comes down to nitpicking as to what is meant by "the depths of the
solar system", but the International Cometary Explorer (ICE, nee IUE or
something), which made a pass at comet G-Z (I'm not even going to try to
remember how to spell it) came from its stationkeeping position near one of the
Earth/Sun Lagrangian points (L1 I believe: the one between us) and made 5
flybys of the earth and/or moon to get its boost on its way to the comet.

Good article though.  Go Giotto!  (And wouldn't it be interesting to see
closeup what kind of shape that comet-beaten probe is in?)

------------------------------

Date: 3 Jul 90 22:21:53 GMT
From: umich!sharkey!wyn386!wybbs![e-mail]  (Ken )
Subject: Re: Reflections on Hubble and NASA

In article <[e-mail]> [e-mail] (alan pengelly) writes:
>
> Okay a mistake has been made, but it is worth remembering
>that HST is a novel concept, completely different to anything
>that has been done before. That good PR pictures will not
>be available for a while is a short term inconvenience. I believe
>when the programme is finished it will be viewed as a success.
> Keep at it NASA.

I wouldn't be too sure about that "it's never been done before statement."
I seem to recall an article in Av Week or Defense News that said that there
were some restrictions placed on the dissemenation of the technical details
about Hubble. It seems the transport case for the Hubble bore a very
strong resemblence to a certain classified military program. Assuming the
appropriate safeguards were made, consider the capability of a Hubble pointed
the other way around...

Ken

--
Ken Jongsma                                  [e-mail]
Smiths Industries                            [e-mail]
Grand Rapids, Michigan                       ..sharkey.cc.umich.edu!wybbs!ken

------------------------------

End of SPACE Digest V12 #11
*******************