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Subject: SPACE Digest V12 #148

SPACE Digest                                     Volume 12 : Issue 148

Today's Topics:
            HST testing (followup)
       Re: Free Space Station - spacious but needs work
              Magellan Update - 07/27/90
              Re: Engineering news group
              Re: HST testing (followup)

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    Submissions to the SPACE Digest/sci.space should be mailed to
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----------------------------------------------------------------------

Date: Sun, 29 Jul 90 20:49:24 EDT
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: HST testing (followup)



>From: rochester![e-mail]  (Ray Frank)
>Subject: Re: Hubble, Shuttle

>>Why do you think we can't do anything about it? Even the TV and newspapers
>>have started to catch on to the idea of correcting the optics in the replacement
>>instruments (which were planned anyway).

>Never the time or money to do it right but always the time and money to do it
>over.

Doing it "right" once the mirrors were completed would have required the
$100 million test. The "cheap" test would have been unsatisfactory for
the same reasons that have been given lately. Assuming the error was found,
it would probably have taken several more years and many millions of dollars
to regrind the mirror, then of course another integrated test (which might
cost less than $100 million for the second use). The time was available due
to the Challenger explosion, but NASA didn't know it then. It's not entirely
certain that Congress wouldn't have gotten disgusted and cancelled the
project right then.

The point is that if the mirror was wrong at this point in time, NASA was
in deep trouble whether they tested or not. If it turns out that the error
was due to incorrect specifications supplied to Perkin Elmer by NASA, then
NASA certainly deserves the full blame in this context. If, however, it
is determined that NASA supplied the correct specs and Perkin Elmer made
some blunder that led to the focus error, I suspect that the finding will
be that NASA had every right to expect that Perkin Elmer would have the mirror
figured correctly at that point in time, and therefore should not have been
expected to require a test of this type. As I mentioned last week, when you
consider performing a test, you have to determine what possible benefit it
can provide. With the expected expenses as they were, there may have been
very little expected benefit from testing at this point. It would be different
if there were no possible recovery from a focus error after launch, but I
suspect that even at this point an analysis of remote contingencies had
revealed that based on what was already known about the mirrors (i.e. their
smoothness), if the [extremely unlikely] event should take place, it could
be corrected by compensatory optics in the [already planned] replacement
instruments. If that is indeed the case (and I have trouble picturing them
foregoing the test if it is not), then it was not a totally "mission-critical"
issue, as several people have implied. While not testing at that point has
led to a reduction in the [utility integrated over lifetime] of HST, the
fact that it is definitely not reduced to zero and the fact that correction
of the problem at that point would also have led to considerable expense
indicates to me that the claim (not by you) that the decision not to perform
that particular test was equivalent to throwing $1.5 billion out the window
is ignorant and irresponsible, even based on what little we know now.
Of course, since the detailed investigation of the Perkin Elmer records is
really just beginning, and we won't *know* what really happened for a month
or two, most of this HST discussion is in the "shooting our mouths off before
we know anything" category. But if it makes us happy... :-) :-)

This might be a rough approximation of the arguments used in the testing
decision:
ACTION                             RESULT
------                             ------
cheap test, find no major error    we get blasted, because it's not a valid
                                   test for minor errors, and there's not
                                   much point in doing one without the other.

expensive test, find no error      we get blasted, because we spent so much
                                   money, and we should have known PE would
                                   be reliable anyway (DoD told us). Also, we
                                   might damage mirror or coating.

any test, find error               we get blasted, because error should have
                                   been found much earlier (even if it's PE's
                                   fault). Hundreds of millions and years to
                                   fix.

no integrated test                 it's highly unlikely that there's anything
                                   wrong with the mirror, especially in light
                                   of PE's reputation and all our other tests.
                                   Anyway, if there is a simple error, we can
                                   fix it with corrective optics. So what if
                                   the focus is bad for a few years.

       John Roberts
       [e-mail]

"1929 it was... the papers were full of it... people said: 'Why'd the bottom
fall out of the market?' Ha! I know! The cat knocked over the canned goods.
Did the experts ask me? No, they...."        - Mouse (Pogo, 1953)

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

Date: 26 Jul 90 15:21:00 GMT
From: cs.utexas.edu!news-server.csri.toronto.edu!torsqnt!tmsoft!masnet!f906.n250.z1.fidonet.org![e-mail]  (maury markowitz)
Subject: Re: Free Space Station - spacious but needs work



  Before we got too far into this, does anyone out there know how to reach
either Global Outposts or External Tanks Corp?  SnailMail or Net addresses
would be appreciated.

 a> Since converting an empty ET to a workspace would be time-consuming
 a> (putting in
 a> pipes, wiring, equipment, etc), is it possible to put in the tank
 a> _before_
 a> filling it?  The piping and wiring shouldn't interfere with the flow
 a> in the
 a> tank.

  Depends on what you define as a station.  Personally, I'd have no
trouble living in a place where there wiring is duct-taped to the walls
and air runs in dryer vent hoses (i'm not kidding).  There are some
thinkgs you CAN'T scimp on, and these present a problem.  For example, air
and water processing is fairly large depending on how much processing vs.
resupply you want to do, and I don't really know if you could get them in
there.

 a> Walls could be installed as a wire mesh strung between the ET walls
 a> (with
 a> doorways.  When it's in orbit, the mesh can be covered with fabric,
 a> plastic
 a> film or whatever is appropriate.

  You just gave me a great idea.  I'll have to talk to my composite freind
(no, he's not MADE of of composites :-) to see if it's possible though
before posting (I've been guilty of foot-in-mouth several times here, I
think I'll follow this one though first!).

 a> Large pieces of equipment, which would be difficult to pass through the
 a> "manhole" could be added before launch.  It could be protected from the
 a> cryogenic propellant with a thin cover or dewar flask if necessary.

  There's a better place, the intertank.  There's no fuel there to take up,
 nothing to protect your equipment from, etc, and you've got about 5000
cubit feet to play with.  Considering that that's bigger than my house
(marginally :-) if you can get everything to fit into the pointy corners,
you're all set.  Have all the wiring and piping ready the be fitted, pass
then in though the end in "Henry's" cylinder and start hooking it up
thought the top end of the tank (if you can, I'm checking on this).
External Tanks Corp will soon be using the intertank region as a large
sounding rocket for microgravity experiments, a very interesting proposal,
and the only one that NASA likes so far.

 a> With all the structures and large equipment pre-installed, turning the
 a> ET into
 a> a viable space lab should be relatively easy.  Attach the dividers
 a> (velcro?),
 a> snap the equipment into the brackets, and that's it.  :)

  I see the smiley there, I assume you refer to the trouble that it always
takes a LOT longer than planned in space.  It all depends on if you've got
people who are willing to go up and start working in lousy (and
dangerous!) conditions.  NASA thinks it's too expensive, and I tend to
agree.  Shouldn't stop us from THINKING about it though!

                                             Maury

--- Maximus-CBCS v1.00
 * Origin: The Frisch Tank, Newmarket, Ontario, CANADA (1:250/906)

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

Date: 29 Jul 90 06:31:58 GMT
From: zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 07/27/90


                           Magellan Status Report
                              July 27, 1990

     The Magellan spacecraft is now 135,950,482 miles from Earth,
3,423,307 miles from Venus and traveling at a heliocentric velocity
of 86,211 mph.  One way light time is 12 minutes 10 seconds.  Magellan
passed spacecraft perihelion at 8:32PM (PDT) on July 23 and is now slightly
inside the orbit of Venus, and will arrive at Venus on August 10.

     The Venus Orbit Insertion (VOI) "Earthquake Contingency Plan" was
completed on July 21, with the storing of contigency VOI command sequences
at the three Deep Space Network (DSN) tracking complexes.  This plan protects
the VOI for Magellan in the event of a catastrophic loss of command
capability at JPL.

     Some more information about the failed gyroscope.  The Magellan
Attitude Control System contains two inertial Attitude Reference Units
(ARU) designated A and B.  Each ARU contains two gyroscopes, designated
1 and 2, and each provides two channels capable of measuring position
errors  about two spacecraft axes.

               Gyro A-1 --> Provides X and Z axis errors
               Gyro A-2 --> Provides X and Y axis errors
               Gyro B-1 --> Provides Y and Z axis errors
               Gyro B-2 --> Provides X and Y axis errors

     On October 2, 1989, gyro B-2 exhibited a failure that was diagnosed
as a dynamic instability in the bearing retainer chatter, and ARU B was
powered down.  ARU B was powered  up on July 20, 1990 to see if the gyro
B-2 could be used for VOI.  The motor was running well but the channel
outputs (X and Y axes) were saturated and never varied.  Gyro B-2 was then
powered off on July 20.

     The cause fo the failure in gyro B-2 is under investigation.  There are
several plausible electronic failures that would cause the symptons.  A
decision was made to leave gyro B-1 powered up, along with ARU A (gyros A-1
and A-2) for VOI.  Gyro B-2 will remain powered down.

     The original purpose of using both ARU's during VOI was that triple-
redundancy was available about the spacecraft's X and Y axes, the major
Solid Rocket Motor (SRM) control axes.  This enabled very fast, direct
detection of a failed gyro.  The present configuration is dual-redundant
and gyro failures are detected indirectly through vehicle dynamics with
fault protection, which takes longer.

     It should be noted that the Magellan design of four gyros is unique
for planetary spacecraft.  Previous spacecraft designs used only three gyros.
The fault protection functions now on Magellan with the three gyros, involves
a risk similiar to other planetary orbit insertions.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 29 Jul 90 21:08:25 GMT
From: [e-mail]  (Daniel Alexander Davis)
Subject: Re: Engineering news group


Although both Ron and I gave examples from our experience of how the
higher education process has failed us, we may have been too hasty.
Less than 75% of the U.S. population is literate.  Could the
communication problems we are interested in affect more than
engineers?

We are also concerned about the general population's awareness of
engineering and engineering issues.  Both of these problems could be
symptoms of the faulty national system we have now.

Could some of the experts here point me towards some children's books
that target the potential engineer?  What characteristics should such
books have?

One obvious book is "The Way Things Work" and variants of such.  I
also remember a book called "The Space Child's Mother Goose", but I
was 19 when I first discovered it.  Is there anybody out there who
read it while they were young?


Dan Davis (is), the Repunzel of the Mathematics Department.
Carnegie Mellon undergraduate
Disclaimer - don't look at me, I'm also a music major,
I don't have to know what I'm doing.
[e-mail](INTERNET).

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

Date: 30 Jul 90 01:12:28 GMT
From: zaphod.mps.ohio-state.edu!uwm.edu!ux1.cso.uiuc.edu!aries![e-mail]  (Doug McDonald)
Subject: Re: HST testing (followup)

In article <[e-mail]> [e-mail] (John Roberts) writes:
>
>
>>From: rochester![e-mail]  (Ray Frank)
>>Subject: Re: Hubble, Shuttle
>
>>>Why do you think we can't do anything about it? Even the TV and newspapers
>>>have started to catch on to the idea of correcting the optics in the replacement
>>>instruments (which were planned anyway).
>
>>Never the time or money to do it right but always the time and money to do it
>>over.
>
>Doing it "right" once the mirrors were completed would have required the
>$100 million test. The "cheap" test would have been unsatisfactory for
>the same reasons that have been given lately. Assuming the error was found,
>it would probably have taken several more years and many millions of dollars
>to regrind the mirror, then of course another integrated test (which might
>cost less than $100 million for the second use). The time was available due
>to the Challenger explosion, but NASA didn't know it then. It's not entirely
>certain that Congress wouldn't have gotten disgusted and cancelled the
>project right then.
>
>The point is that if the mirror was wrong at this point in time, NASA was
>in deep trouble whether they tested or not. If it turns out that the error
>was due to incorrect specifications supplied to Perkin Elmer by NASA, then
>NASA certainly deserves the full blame in this context. If, however, it
>is determined that NASA supplied the correct specs and Perkin Elmer made
>some blunder that led to the focus error, I suspect that the finding will
>be that NASA had every right to expect that Perkin Elmer would have the mirror
>figured correctly at that point in time, and therefore should not have been
>expected to require a test of this type. As I mentioned last week, when you
>consider performing a test, you have to determine what possible benefit it
>can provide. With the expected expenses as they were, there may have been
>very little expected benefit from testing at this point. It would be different
>if there were no possible recovery from a focus error after launch, but I
>suspect that even at this point an analysis of remote contingencies had
>revealed that based on what was already known about the mirrors (i.e. their
>smoothness), if the [extremely unlikely] event should take place, it could
>be corrected by compensatory optics in the [already planned] replacement
>instruments. If that is indeed the case (and I have trouble picturing them
>foregoing the test if it is not), then it was not a totally "mission-critical"
>issue, as several people have implied. While not testing at that point has
>led to a reduction in the [utility integrated over lifetime] of HST, the
>fact that it is definitely not reduced to zero and the fact that correction
>of the problem at that point would also have led to considerable expense
>indicates to me that the claim (not by you) that the decision not to perform
>that particular test was equivalent to throwing $1.5 billion out the window
>is ignorant and irresponsible, even based on what little we know now.
>Of course, since the detailed investigation of the Perkin Elmer records is
>really just beginning, and we won't *know* what really happened for a month
>or two, most of this HST discussion is in the "shooting our mouths off before
>we know anything" category. But if it makes us happy... :-) :-)
>
>This might be a rough approximation of the arguments used in the testing
>decision:
>ACTION                             RESULT
>------                             ------
>cheap test, find no major error    we get blasted, because it's not a valid
>                                   test for minor errors, and there's not
>                                   much point in doing one without the other.
>
>expensive test, find no error      we get blasted, because we spent so much
>                                   money, and we should have known PE would
>                                   be reliable anyway (DoD told us). Also, we
>                                   might damage mirror or coating.
>
>any test, find error               we get blasted, because error should have
>                                   been found much earlier (even if it's PE's
>                                   fault). Hundreds of millions and years to
>                                   fix.
>
>no integrated test                 it's highly unlikely that there's anything
>                                   wrong with the mirror, especially in light
>                                   of PE's reputation and all our other tests.
>                                   Anyway, if there is a simple error, we can
>                                   fix it with corrective optics. So what if
>                                   the focus is bad for a few years.
>
>       John Roberts
>       [e-mail]
>
>"1929 it was... the papers were full of it... people said: 'Why'd the bottom
>fall out of the market?' Ha! I know! The cat knocked over the canned goods.
>Did the experts ask me? No, they...."        - Mouse (Pogo, 1953)


This is a long quote. Sorry. I'll give it because the retort is so
simple: there was another mirror made. IF a real test had been done,
it is unlikely that the second mirror woudl have had a serious error.
IF it did, of course, then money (not necessarily the taxpayer's)
would have been needed for fixing it. BUT if the second one was OK -
no more cost. AND we would have KNOWN about Perkin-Elmer's
incompetence earlier.

Doug McDonald

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

End of SPACE Digest V12 #148
*******************