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Subject: SPACE Digest V11 #587

SPACE Digest                                     Volume 11 : Issue 587

Today's Topics:
     Re: Is there a backup HST mirror ??? (see sci.astro)
               Re: Magnetic solar sail?
        Re: More on NASA 91 Appropriation Vote
          Trying to locate Donald K. (Deke) Slayton
              HST focus problem
           Re: What Spherical Aberration is
          Re: ESA-brief summary of activity
           Re: Anyone Know What MOL Is/Was?
         Re: Is there a backup HST mirror ???
               RE: public image of HST
               Re: 10 psi overpressure
Re: NASA announces next steps in Space Exploration Outreach Program (F
           Re: Anyone Know What MOL Is/Was?
           Hubble Space Telescope Update - 06/27/90

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: 29 Jun 90 00:21:32 GMT
From: zaphod.mps.ohio-state.edu!swrinde!emory!mephisto!prism![e-mail]  (Matthew DeLuca)
Subject: Re: Is there a backup HST mirror ??? (see sci.astro)

In article <[e-mail]> [e-mail] (Fraering Philip) writes:
>
>_Maybe_, with the shuttle backlog being the way it is, a
>Buran could be used...

I don't know about you, but I wouldn't want *my* billion-dollar space toy
brought home on something that has (a) only flown once, (b) won't fly
again until 1991, and (c) has had its pilots refuse to fly it, due to
instrumentation and redundancy problems.  I think I'd like to see it fly a
few times first.

--
Matthew DeLuca
Georgia Institute of Technology      Do not meddle in the affairs of wizards,
Office of Computing Services         for they are subtle, and quick to anger.
ARPA: [e-mail]

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

Date: 28 Jun 90 05:14:51 GMT
From: swrinde!zaphod.mps.ohio-state.edu!sunybcs!ubvms.cc.buffalo.edu![e-mail]  (collie)
Subject: Re: Magnetic solar sail?

In article <[e-mail]>, [e-mail] (Keith F. Lynch) writes...
>> A magnetic sail uses the fact that the solar system has a magnetic
>> field.  You take a superconducter ring, and start a current in it,
>> it now has a magnetic field, and the one for the solar system
>> pushes against it.

>This doesn't sound right.  A magnet in space will tend to orient
>itself in the direction of the field lines.  But magnetic *attraction*
>is due to the *difference* in magnetic flux from one side of the
>magnet to the other.  This is why magnets on earth have little
>tendency to hurtle northward (or southward).  The magnetic domain
>of space is even flatter.

>[ I just heard on the radio that the HST mirror is seriously warped. ]

>                                ...Keith
                     ****************************


          This is horrible news for NASA as the public would start crying
 even more about the 1.5 bill. price tag,and will further loose fate in any
 NASA plans for the future.I can now see the space station Freedom size
 getting even smaller,as the purse string draws even tighter.Where
 I stand,this is not a good sign.


             1)   What cause the mirror to become warped ?

             2)   What is the prognosis for the H.S.T now ?

                      ******************************

********************************************************************************

                        Can there be order in Chaos ?

*******************************************************************************

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

Date: 27 Jun 90 23:51:33 GMT
From: usc!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (David Anderman)
Subject: Re: More on NASA 91 Appropriation Vote

I'm curious to know the mechanics of how Andy Cutler gets to determine
the final mission architecture of the SEI? Or, for that matter, how you
or I could participate in the definition of the project.
If no funds are voted this year for the project does this mean that we
get to participate in the project next year (assuming it is funded next
year)?


--- Opus-CBCS 1.13
 * Origin: Universal Electronics, Inc. (1:103/302.0)
--
uucp:     David Anderman
Internet: [e-mail]
BBS:      714 544-0934   2400/1200/300

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

Date: 28 Jun 90 14:42:34 GMT
From: uc!shamash!timbuk![e-mail]  (Lou Adornato)
Subject: Trying to locate Donald K. (Deke) Slayton

Dear fellow netters -

I _desperately_ need to get in touch with former astronaut office head
(and former astronaut) Donald K. (Deke) Slayton.  The last I heard he
was at American Rocket (AMROC), but I don't know if he's still there or
not, or where thier headquarters might be.

If anyone has _any_ information that might help (especially the
location of AMROC headquarters), _please_ email to me at [e-mail]
BEFORE July 10.

Thanks in advance.

Lou Adornato    |  Statements herein do not represent the opinions or
Cray Research   |  attitudes of Cray Research, Inc. or its subsidiaries.
[e-mail]    |       (...yet)

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

Date: 28 Jun 90 14:50:59 GMT
From: usc!cs.utexas.edu!asuvax!hrc!gtx![e-mail]  (Alan Filipski)
Subject: HST focus problem


Couldn't this be corrected by digitally post-processing the image?
By looking at stars you can evaluate the point spread function
at each point of the field. The distortion of non-point objects
could be modeled as a linear combination of these point spreads.
As long as this function is invertible (which seems likely)
you could reconstruct the image you want from the distorted image.

This is a standard image-processing technique.  Could it be used here?


  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ( Alan Filipski, GTX Corp, 8836 N. 23rd Avenue, Phoenix, Arizona 85021, USA )
 ( {decvax,hplabs,uunet!amdahl,nsc}!sun!sunburn!gtx!al         [phone] )
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

Date: 28 Jun 90 18:17:15 GMT
From: cscs![e-mail]  (Craig E. Smith)
Subject: Re: What Spherical Aberration is

In <[e-mail]> [e-mail] (Greg S. Hennessy) writes:

>Once more with feeling.

>Since HST is apparently suffering from Spherical aberration, and
>seeing how lousy the news reports were tonight, I thought I would give
>the readers a brief summary of what spherical aberration is.
> ...


        Does anyone know if it is possible to correct for spherical
aberration, or at least reduce its effects significantly, by the
use of advanced computer image analysis techniques.

--
The truly proud man knows neither superiors | Internet: [e-mail]
nor inferiors.  The first he does not admit | UUCP:     ... uunet!cscs!csmith
of - the last he does not concern himself   |
about.  - William Hazlitt                   |

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

Date: 26 Jun 90 16:56:23 GMT
From: zephyr.ens.tek.com!tekfdi!videovax![e-mail]  (Donald M. Craig)
Subject: Re: ESA-brief summary of activity

In <[e-mail]> [e-mail] (M.sean Bennett)
writes: "Beginning on
19 February, a series of telecommands was transmitted to Giotto via the Madrid
tracking station, using a 70m antenna and a 100000 W transmitter, many thousand
times the power of a TV broadcasting station."
Reaching for my trusty Television and Cable Factbook, which lists in gory
detail facts about all US television stations, I extracted the following:
KNLC, Channel 24 (530 - 536 MHz), St. Louis, MO, Authorized power: 3090-kw
max. visual, 309-kw max.aural.
WTZA, Channel 62 (758 - 764 Mhz), Poughkeepsie, NY, Authorized power: 5000-kw
max. visual, 500-kw max. aural.
KICU, Channel 36 (602 - 608 MHz), San Jose, CA, Authorized power: 4098-kw
max. visual, 410-kw max. aural.
That's 3 million watts, 5 million watts, and 4 million watts.  Perhaps the
100000 W number was a typo?
cheers,
Don Craig
Tektronix Television Division, [e-mail]

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

Date: 28 Jun 90 15:35:49 GMT
From: orc!inews!td2cad!yoyodyne![e-mail]  (john reece)
Subject: Re: Anyone Know What MOL Is/Was?

In article <[e-mail]>,
[e-mail] (r.craig.montero) writes:
> Actually, there was a test of a Gemini vehicle with a circular hatch cut
> through the heat shield. The Gemini vehicle had actually flown one of the
> manned missions and was refurbished (and given a new heatshield) enough
> to fly on a short (one orbit?) mission.

Where was the hatch located with respect to the astronauts seats, and
how were they supposed to move around inside the capsule to get to it?
I remember reading about how the Gemini astronauts had to practically
be shoehorned into their seats, and how it was so cramped astronauts had
difficulty after EVAs getting back into the vehicle on their own.

John Reece
Not an Intel spokesman
[e-mail]

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

Date: 28 Jun 90 16:22:25 GMT
From: clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Is there a backup HST mirror ???

In article <[e-mail]> [e-mail] writes:
>>>Now that the HST is safely in orbit, what happens to the backup mirror...
>>Providing that one does actually exist, it may be sent up to fix the
>>"spherical aberration" mentioned in another article. ;)
>        No.The cost would be too high for NASA,and the G.A.O also
>  would kick up a big fuss.(The purse is closed.)

The HST purse is not closed, since there has been work underway for quite
some time on upgraded instruments and the like for HST.  The schedule as
it was until a few days ago called, as I recall, for a shuttle visit in
1993-4 with an improved WideField/PlanetaryCamera and replacements for
the solar arrays and batteries, and another in 1997-8 to replace the two
spectrometers with a newer general-purpose spectrometer and an infrared
instrument (combination imager and spectrometer, I think).  There is some
small likelihood of changes to this plan now. :-)

However... although HST was designed for various forms of maintenance in
orbit, I don't think replacing the main mirror was among them!  It just
might be possible to replace the secondary mirror.  There was a backup
main mirror, built by Kodak, but I don't think launching it is a realistic
possibility.  (I'm not sure how far it went towards completion, also.)

There is talk of a mission in 1991 -- one had been pencilled in as a
contingency in case something went badly wrong -- but I suspect that's
a little too soon for something as drastic as mirror replacement.  If
a replacement WFPC with aberration compensation can be built in haste,
that might perhaps be done.
--
"Either NFS must be scrapped or NFS    | Henry Spencer at U of Toronto Zoology
must be changed."      -John Osterhout |  [e-mail]   utzoo!henry

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

Date: 28 Jun 90 23:17:14 GMT
From: zaphod.mps.ohio-state.edu!uwm.edu!bionet!hayes.fai.alaska.edu!acad3.fai.alaska.edu![e-mail]  (THOMAS DAVID J)
Subject: RE: public image of HST


In <[e-mail]>, Andrew Palfreyman writes:

>If I try to put myself into the mind of Joe Public (not difficult), I would
>feel very angry (about my $1.5B) and also very amazed about defective
>mirrors. After all, there was a whole lot of wingeing from the scientific
>community, via the media, as Hubble rose into the limelight around its
>launch date, about how long it had languished in storage. Since the
>mid-80's, wasn't it?

>So I would say the reaction would be amazement that mirror testing of
>some sort was not done in the 6-ish *YEARS* available to ground crews.

I must agree that the general public will probably react to the current events
in the manner Mr. Palfreyman describes.  However, as Ron Baalke at JPL has
pointed out, the mechanisms of the HST are too sensitive to be tested in
Earth-normal gravity.

Our space program, as old as it is, is still quite experimental.  With
investments (scientific and financial) as large as the HST, there are bound
to be risks.  However, I believe that the potential benefits are well worth the
risks.

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

Date: 27 Jun 90 16:15:03 GMT
From: mojo![e-mail]  (Doug Mohney)
Subject: Re: 10 psi overpressure

In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
>>>NASA point-blank refuses to put destruct charges aboard the orbiter.
>>
>>I seem to recall that the charges went in by the SSMEs ...
>
>References, please?  The Rogers Commission report, among other sources,
>is quite explicit that there are no destruct charges on the orbiter and
>never have been.

This was a post-Rogers, post-Challenger launch. Other than that, I'll have
to dig through AvWeek to find the reference.

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

Date: 28 Jun 90 00:51:23 GMT
From: thorin!algol![e-mail]  (Jonathan Leech)
Subject: Re: NASA announces next steps in Space Exploration Outreach Program (F

In article <[e-mail]> [e-mail] (*Greg*) writes:
>Getting idea's from proper scientwits is the best way to obtain lowcost
                ^

    This gets my vote for best neologism on sci.space.
--
    Jon Leech ([e-mail])    __@/
    "Student Activism 1968-69 Oct 23: 15 students picket the Circus
     Room to protest the poor quality of UNC sandwiches."
    _The Daily Tar Heel_, 11/15/89

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

Date: 28 Jun 90 02:26:41 GMT
From: att!cbnewsj![e-mail]  (r.craig.montero)
Subject: Re: Anyone Know What MOL Is/Was?

In article <[e-mail]> [e-mail] (Gavin Eadie) writes:
>The best part was that access to the tank was through a hatch cut in the
>heatshield of the Gemini. I always wondered if that could actually work
>without excessive risk ... we'll never know!

Actually, there was a test of a Gemini vehicle with a circular hatch cut
through the heat shield. The Gemini vehicle had actually flown one of the
manned missions and was refurbished (and given a new heatshield) enough
to fly on a short (one orbit?) mission.

Thus, Columbia was not truly the first spacecraft to be re-used (certainly
manned re-use of course).

The test was rated a success, but did not help save the MOL concept.

This information was retrieved from memory, but is from one of the many texts
written shortly after the Apollo 11 mission about how we got to the moon.
The title and author escape me, although I do know it was not Collins' book.

Hope this helps.

Craig Montero
[e-mail]

insert STANDARD DISCLAIMER here

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

Date: 28 Jun 90 16:44:57 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Hubble Space Telescope Update - 06/27/90


                           Hubble Space Telescope Update
                                 June 27, 1990

    Dr. Lew Allen, director at the Jet Propulsion Lab, has been selected to
lead the inquiry board to investigate the spherical aberrations in the
telescope's mirror system.

     The two mirrors on HST are components of the Optical Telescope
Assembly (OTA).  The optical system is a variation of a Cassegrain
design, called Ritchey-Chretien, which uses a folded design to enable
a long focal length of 189 feet to be packaged into a small telescope
length of 21 feet.  Both mirrors are hyperboloidal in shape, meaning they
have a slightly deeper curvature than a parabolic mirror.  This shape was
to correct all coma and spherical aberations everywhere in the field of
view.  The OTA takes incoming light down its tubular baffle.  The light
is reflected off the 94.5 inch primary mirror to the 12.2 inch secondary
mirror.  The light is then reflected by the secondary mirror through a
hole in the primary mirror to the focal plane. From the focal plane, the
Scientific Instruments (SI) and the Fine Guidance Sensors (FGS) recieve
the light.  The OTA was designed and built by the Perkin-Elmer Corporation.

     The telecope was designed such that 90% of the equipment and
instrumentation has a backup or identical unit. Components on the telecope
which were critcial subsystems and might possibly degrade over time were
packaged into what are called Oribital Replaceable Units (ORU), which could
be easily replaced in orbit in one piece.  There are 70 ORUs on HST ranging
from small fuse plugs to the telephone-booth size FOC.  The telecope's two
mirrors are not in an ORU package.

     Very little has happened in orbit during the past 24 hours, but the
next 24 hours should see an OTA test, Faint Object Spectrograph (FOS) High
Voltage (HV) turned on and tests of the High Speed Photometer (HSP)
Photomultiplier Tube (PMT) detector.

     On the Pointing Control Subsystem (PCS) instabilities, it may be possible
to remove most of the disturbances seen in the HST pointing to reduce the
amplitude of the disturbance by at least a factor of 10 and maybe by as much
as a factor of 100, and do this ahead of schedule (late July instead of early
August). The Fixed Head Star Tracker (FHST) produced two large updates
yesterday, these precipitated a few failed acquisitions.  The Fine Guidance
Sensor (FGS) S-Curve calibration is in progress.

     The Faint Object Camera (FOC) is in hold.  FOC diagnostic images in
support of focus efforts may start on July 1.

     The Goddard High Resolution Spectrograph (GHRS) is in hold.  The HV
electronic dark count test apparently went well, the data is being analyzed
at this time.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

End of SPACE Digest V11 #587
*******************