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Subject: SPACE Digest V11 #583

SPACE Digest                                     Volume 11 : Issue 583

Today's Topics:
         Re: Hubble Space Telescope Update - 06/27/90
     Re: Is there a backup HST mirror ??? (see sci.astro)
            Re: The end of Hubble
            Re: HST focus problem
           Re: ATTENTION URGENT MAYDAY!!!!
  The Manned Orbiting Laboratory (was: Anyone Know What MOL Is/Was?)
       Re: NASA Headline News for 06/26/90 (Forwarded)
      Correction to NASA Headline News for 06/27/90 (Forwarded)
             Magnetic solar sail?
           Re: Moon - model rocket contest

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: 28 Jun 90 19:56:23 GMT
From: zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jato!mars![e-mail]  (Ron Baalke)
Subject: Re: Hubble Space Telescope Update - 06/27/90

In article <[e-mail]> [e-mail] (Al Bowers) writes:
>
>In article    From: [e-mail] (Ron Baalke)
>
>
>>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.
>
>Now, I'm certainly no optical expert, but isn't a Ritchey-Chretien's
>secondary an elliptical mirror?  I do know it provides a flat field,
>no coma, no spherical aberration, no chromatic aberration (being a
>reflector telescope).

The secondary mirror is convex hyperboloid (flat on one side, curved on the
other). The primary mirror is hyperboloid (curved) on both sides.

>It does have off axis astigmatism though.
>

Yes, and aberrations in field curvature as well.  Both the astigmatism and
field curvature aberrations are exactly zero in the center of the field and
increasing towards the edge of field.  Theses aberrations are easily
corrected within the scientific instrument's optics.  For example, the
Faint Object Camera has a small telescope designed to remove the image
astigmatism.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 28 Jun 90 20:35:19 GMT
From: uoft02.utoledo.edu![e-mail]
Subject: Re: Is there a backup HST mirror ??? (see sci.astro)

In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
> 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




Note that there is no way to change either mirror without bringing the
telescope back to earth.

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

NOTE:  For those following HST, most of these things are being answered
in ssi.astro so you may wish to look there for further details.  A lot
is not being crossposted to sci.space.

Robert Dempsey
Ritter Observatory

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

Date: 28 Jun 90 23:12:06 GMT
From: voder!dtg.nsc.com![e-mail]  (Lord Snooty @ The Giant Poisoned Electric Head )
Subject: Re: The end of Hubble


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.

The media coverage is uniformly "disguised sneering" as far as I have seen
(CNN, local channels). This may be a blow to public perception of the space
program similar in magnitude to Challenger; well, worse - the sympathy
factor is totally lacking here!
--
...........................................................................
Andrew Palfreyman    that asteroid has our names on it
[e-mail]            " 'course, the 'addock's very nice "

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

Date: 29 Jun 90 01:58:10 GMT
From: uoft02.utoledo.edu![e-mail]
Subject: Re: HST focus problem

In article <[e-mail]>, [e-mail] (Alan Filipski) writes:
>
> 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?
>
>
>

I don't know, it might for WFPC.  But for the high res spectrograph and the
photometer it means a serious degradation of throughput with the 2"
image.  This will also make absolute calibrations more difficult.  There
are still alot o fthings it can do that ground based telescopes can't.

Robert Dempsey
Ritter Observatory

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

Date: 27 Jun 90 15:23:51 GMT
From: hpfcso!hppad![e-mail]  (Steve Horvath)
Subject: Re: ATTENTION URGENT MAYDAY!!!!


    Okay! ... message forwarded by to staff at York U. by phone at
    11:22 am June 27,1990.  Ought to be forwarded to J.H. this afternoon.
        sincerely S.H.

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

Date: 27 Jun 90 13:42:18 GMT
From: frooz!cfa250![e-mail]  (Jonathan McDowell)
Subject: The Manned Orbiting Laboratory (was: Anyone Know What MOL Is/Was?)

----  The Space Station that Never Flew: MOL ------


From article <[e-mail]>, by [e-mail] (John A. Weeks III):
> While looking at the space suit exhibits at the Kansas
> State Cosmoshere recently, I saw a space suit from the
> "MOL" project.  Although I have looked through all of
> my space books, I have been unable to find out anything
> about MOL except the following:
>
>   1. It stands for Manned Orbiting Labratory
>   2. It was a super-secret Air Force project
>   3. It was cancelled in 1968
>
> Can anyone tell me more about MOL?

The USAF has been trying to get a piloted space program
for decades; they keep getting cancelled. The first was the
X-20 spaceplane, cancelled in 1962 before its first flight.
However, the booster for the X-20 did complete its development,
and was named Titan III (sound familiar?). Next came MOL.
MOL was to be America's first space station, and it would be
a military one. The Titan IIIC was to be upgraded to become a
Titan IIIM; MOL would be launched on top of it. The structure
of MOL had two components; a lab module and a ferry craft.
But while NASA's later Skylab used Apollo/Saturn technology,
MOL used the older Gemini/Titan technology.

The MOL lab module was based on the Titan stage 2 structure;
the MOL ferry craft was Gemini B, a modified Gemini craft with
- get this - a hatch carved in the HEATSHIELD! The Gemini was
attached to MOL like so:

        ______________________________
  __ --/      |  |                    |
 |__ Gemini          MOL              |
    `--\______|__|____________________|

              ^
              |
            Heat shield with tunnel cut through

and at the end of the mission the astros would crawl back into
Gemini, close the hatch real tight, Gemini would separate and
reenter. While up there, the astros would carry out unspecified
tasks, and unspecified payloads would operate (actually, it
is believed, a large USAF/NRO KH-10 camera system would be
clicking away).

Well, they got to the point of building hardware. Three groups
of astronauts were selected, a total of 17. A test mission was
flown - the Gemini 2 spacecraft which had flown a suborbital
unpiloted test flight in Jan 1965 was converted to a Gemini B
with the heat shield transfer hatch, and connected to a mockup
MOL lab made of a spare Titan 2 tank. The assembly was put
on a Titan IIIC, and launched from Kennedy on 3 Nov 1966.
The rocket rose to 197 km, then was pitched down into a fast dive.
The Gemini B was separated at 166 km and seared into the atmosphere
in a hard test of the heat shield. Meanwhile, the Titan pitched up
again and put the MOL mockup in orbit at 300 km, together with
some small science experiments.

However, real hardware for the program was behind schedule,
and after many delays the program fell victim to the Vietnam
war and  was scrapped in 1969. Some of the remaining astros
were transferred to the  NASA program, others returned to
the military and ended up in senior space related posts.

MOL astronauts were: (it's a fairly impressive list!)

Mike Adams, selected 1965, left 1966 to join X-15 program. Died on the way back
            from space (80km suborbital flight) in the disintegration of the
            X-15-3, Nov 1967.

Dick Truly, selected 1965, joined NASA 1969, flew in space 1981.
            Commander STS-2, STS-8, current NASA Administrator; Admiral USN

Bob Crippen, selected 1966, joined NASA 1969, flew in space 1981.
            Pilot STS-1, Commander STS-7, 41-C, 41-G. Current head of
            Space Shuttle Program.

Gordo Fullerton, selected 1966, joined NASA 1969, flew in space 1982.
            Pilot STS-3, Commander STS-51F. Transferred to Edwards in
            1986, top test pilot and flies Shuttle Carrier Aircraft (747).

Hank Hartsfield, selected 1966, joined NASA 1969, flew in space 1982.
            Pilot STS-4, Commander 41-D, 61-A. Now senior manager at NASA HQ.

'Bo' Bobko, selected 1966, to NASA 1969, flew in space 1983.
            Commander STS-6, 51-D, 51-J.    Resigned 1988.

Bob Overmeyer, selected 1966, to NASA 1969, flew in space 1982.
            Pilot STS-5, Commander 51-B. Resigned 1986.

James "Luke Skywalker" Abrahamson, selected 1967, back to USAF duty
            in 1969. Was Director, Strategic Defense Initiative Org,
            a.k.a.  Chief Star Warrior, from 1984 to 1988.  Now VP at
            Hughes Aircraft. Lt-Gen USAF, ret.

Robert Herres, sel. 1967, was Commander-in-Chief USAF Space Command
            1984-1986, then Vice Chief of Staff USAF; ret 1990 as
            Lt-Gen USAF.

Donald Peterson, sel. 1967, to NASA 1969, flew in space 1983 on STS-6,
            resigned 1984.

Robert Lawrence, sel 1967 as first black astronaut candidate, killed
            Dec 1967 in jet crash at Edwards.

James Taylor, sel. 1965, killed in jet crash at Edwards, Sep 1970.

Albert Crews, sel. 1965, went to work at NASA-JSC after MOL cancelled.
John Finley, sel. 1965, retired from Navy in 1980.
Richard Lawyer, sel. 1965, retired from USAF in 1983.
Lachlan Macleay, sel. 1965, retired from USAF in 1978.
Greg Neubeck, sel. 1965, retired from USAF in 1982.

------------------------------------------------------------------------------
  - hope you find this interesting. Jonathan

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

Date: 27 Jun 90 18:20:47 GMT
From: ksr![e-mail]  (Chris Jones)
Subject: Re: NASA Headline News for 06/26/90 (Forwarded)

In article <[e-mail]>, yee@trident (Peter E. Yee) writes:
>                              the
>orbiter Endeavor currently under construction

Yoiks!  Weren't we all supposed to remember that as the Endeavour with a 'u'?
Can't NASA remember these things?

Am I wrong, or has the name changed?

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

Date: 27 Jun 90 21:14:39 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Correction to NASA Headline News for 06/27/90 (Forwarded)

In Headline News for 6/27/90 there is mention of Magellan's
distance to Venus (250,000).  The correct distance is 9,250,000.
We regret this error!
Chas Redmond

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

Date: Wed, 27 Jun 90 23:28:09 EDT
From: [e-mail] (Keith F. Lynch)
To: milton!maven![e-mail]
Subject: Magnetic solar sail?
Cc: [e-mail], [e-mail]

> 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

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

Date: 28 Jun 90 19:44:45 GMT
From: swrinde!zaphod.mps.ohio-state.edu!sunybcs![e-mail]  (james j richmond)
Subject: Re: Moon - model rocket contest



This is just to let you all know that a group of us with the mode of
our position being Buffalo, NY are starting to plan.  We will soon
(as soon as we get thrust curves from suppliers) have numbers on
staging, and possible max mass in orbit for different combinations
of staging (I wish this stuff was easily optimized).  If anyone has
thrust vs time curves digitized I would appreciate it if you would
make them available over the net.  If no one does I will end up
digitizing the curves by `hand' and using the data for analysis.

It might be a good idea for someone to set up a mailing list for
interested people to communicate through.

===============================================================================
[e-mail]    Jim Richmond               Experimental Physics@UB

===============================================================================
[e-mail]    Jim Richmond               Experimental Physics@UB

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

End of SPACE Digest V11 #583
*******************