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Subject: SPACE Digest V12 #484

SPACE Digest                                     Volume 12 : Issue 484

Today's Topics:
           Hubble Space Telescope Update - 10/12/90
           Re: NAVY WITHOLDING EVIDENCE!!!
            Re: Galileo Update - 10/19/90
             Re: Theories needed on life
        Re: planetary cartographic coordinates

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Date: 23 Oct 90 23:02:38 GMT
From: usc!elroy.jpl.nasa.gov!forsight!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Hubble Space Telescope Update - 10/12/90

The following is forwared from Ron Polidan, astronomer on the HST team
------------------------------------------------------------------------

                               HST Status Report
                               October 12, 1990

Back Again

I suspect many were wondering if my HST status reports had stopped.  After two
weeks in Italy it took me a lot longer to "come up to speed" on the status of
HST then I was expecting.  This combined with a much higher density of meetings
since my return delayed the issuing of this report by about a week.  Beginning
with this report I will be back to the twice a week schedule that I had
maintained since July.  Since a lot has happened since my last report (18
September) I will not attempt to give a summary of everything that has happened
since 18 September in todays report.  Rather, in this report I will give
highlights (with some discussion) of events of the past 3 weeks with details
appearing in the next 3 or 4 reports.

Current Status and Summary

All is going reasonably well with HST.  In general the past three weeks have
passed without major observatory problems.  This is not to say all went
perfectly, there were the "usual" HST problems and the associated loss of data
these past weeks.  The SAGA (Solar Array Gain Augmentation, the day/night
terminator disturbance) fix has arrived at GSFC (Goddard Space Flight Center)
and is under review.  A lot of work has been done on the FHST (Fixed Head Star
Tracker) and FGS (Fine Guidance Sensors) problems that have plagued HST since
launch.  There have been no fundamental breakthroughs on either of these two
problems but steady progress is being made.  The SI's (Scientific Instruments)
were rather active these past weeks.  Significant advancement of the GHRS
(Goddard High Resolution Spectrograph) and the FOS (Faint Object Spectrograph)
toward science operation occurred during the past three weeks with GHRS
getting their first spectrum.  The only SI problem uncovered is that the FOS
Blue side has a magnetic shielding problem similar to but significantly smaller
than that seen on the Red side.  A UV flood guiding test for the WFPC (Wide
Field/Planetary Camera) was partially successful: the sun was clearly detected
but the pointing was a little farther off than desired. Numerous SAO/ERO
(Science Assessment Observations/Early Release Observations) were obtained,
most were quite successful.


Allen Committee Findings

Nothing significantly new here since my mid-September reports.


PCS (Pointing Control Subsystem)

There was lots of news on the PCS front in the past 3 weeks.  The long awaited
PCS fix has been delivered to GSFC and is undergoing final review.
Expectations are high that it will solve most (but not all) of the jitter
problems.  There is a meeting late yesterday (Thursday) to review arguments
with regards to the installation of the delivered software.  Since this is
flight software the primary concern is safety, although performance is
certainly being discussed.  As of the moment, no problems were found and,
pending one final high level review, all is set for installation.  Nothing
really new has happened with the FHST's.  A lot more data has been gathered, a
special tiger team has been formed, and some real progress is being made but
there has not been a significant change in the failure rate over the past 3
weeks.  The optimism that the problems with the FGS's will be removed with
"fine tuning" has virtually vanished.  Test and analyses done over the past
weeks now seem to suggest that fine tuning will do little to affect the quality
of the S-curves.  What is specifically causing the problem has not yet been
identified.  Needless to say this problem is getting high visibility.


HST Focusing and Image Quality

Nothing new here since mid-September.


ERO and SAO Programs

A number of new SAO/ERO observations were obtained over the past three weeks.
Two "new" aspects of the SAO/ERO program have occurred:  the first "Sky Survey
Snapshots" were obtained with the WFPC and the first spectrographic
observations by HST (GHRS) were completed.  The function and use of the Sky
Survey Snapshots were discussed in my previous report and are briefly discussed
below.  Below is an updated listing of the completed (and in progress) SAO and
ERO observations (both successful and failed observations) with a brief
description of the results.  Since this SAO/ERO list is getting rather long,
beginning with my next report I will include only new SAO/ERO observations or
updates on old observations reported in earlier Status Reports.

FOC (Faint Object Camera) observations:

   o PKS0521-36, a radio galaxy with a jet (SAO):   the jet has been detected.

   o AP Lib, QSO with fuzz (SAO):   fuzz is detected.

   o Arp 220, colliding galaxy (ERO), failed.

   o Crab Nebula, SN remnant (ERO), failed.

   o HH1, Herbig-Haro object (ERO), failed.

   o R136, LMC cluster (SAO):   underexposed in both F/96 and F/288 but good
     data.

   o R Aqr: symbiotic star with mass ejection (SAO): very interesting exposure.
     The "tail" is seen in [O II] and [O III].

   o SN 1987A, "THE" supernova (SAO):  ring of gas seen in [O III] and not the
     continuum.

   o Ton 256, QSO with fuzz (ERO):   successful exposure but no fuzz seen.

   o M 14, looking for a historical nova in the globular cluster (an FOS SAO
     proposal):   good deep image.

   o G2237+0305, gravitational lens (SAO):   four distinct objects are seen
     along with something (fifth QSO image or galactic nucleus) at or near the
     center of the lensing galaxy.

   o Pluto/Charon: (SAO) First observation: partial success 4 F/288 images
     (F342W and F430W).  No F/96 images.  Second observation: a partial
     success, this time with good F/96 images but most of the F/288 data lost.

   o 3C66-B, radio galaxy (SAO), successful.


GHRS observations:

   o chi Lup, Hg rich CP star (SAO), partial success.  A good Large Science
     Aperture spectrum but no Small Science Aperture data.

   o xi Per, interstellar line star (SAO), successful.  Data in both apertures
     was obtained, but the star was not centered in either aperture.

WFPC images:

   o NGC 1850, LMC cluster (SAO):  partial success only in 2 attempts.

   o NGC 7457, a normal S0 galaxy (SAO):   analysis of the unexpectedly bright
     core was found at the center of this galaxy is in progress.

   o NGC 925, an intermediate distance galaxy (SAO):   underexposed -- did not
     get very deep.

   o 1Zw1, active galaxy (ERO), failed.

   o NGC 1068, looking at the core of a seyfert galaxy (an FOS SAO proposal):
     structure seen in the nucleus.

   o R136, cluster in LMC (ERO):   analysis in progress.

   o Saturn and Titan, self explanatory (ERO):   analysis in progress.

   o M 15, globular cluster, first observation failed, a repeat was successful.
     Data is under study.

   o eta Car, young cluster (ERO),  first attempt failed, second attempt
     successful.

   o Comet Levy, comet, successful.

The "Sky Survey Snapshot" observations with the WFPC are very short
observations of galaxies, performed under gyro control only, that are used as
fillers in orbits were the planned observation finishes with usable observing
time remaining.  The galaxies are selected on the basis of their proximity to
the planned OV or SV observation target from a master list generated by
J. Bahcall, R. Doxsey, J. Gunn, O. Lahav, and D. Schneider.  Below is a list of
those that have observed over the past weeks, at the moment I do not have any
quality assessment of these observations, this will appear in a future report.

Sky Survey Snapshot Targets:

    S50014+48           Q0451-418           IE1711+712
    PKS0355-48          PKS0506-61          IE1704+710
    B20149+33           Q0551-366           4C58.27
    B20201+36B          PKS0743-67          1613.7+171
    PKS0225-01          S51039+81           PKS2150+05


SMS's (Science Mission Specifications)

All is going smoothly.  SMS's are being maintained at 7 day durations, running
from Monday through Sunday.  Most activity in the recent SMS's have been
SAO/ERO observations or SI OV/SV proposals.  The first round of OTA (Optical
Telescope Assembly) image characterization is and the next image
characterization effort, the HARP (Hubble Aberration Recovery Program) proposal
for the WFPC is scheduled to begin in the SMS that stars on 22 October.  The
SAGA installation is scheduled to begin on Monday (15 October) and will take 5
days to check out.  During this time SI activities will continue.  The first
attempt at fine lock with the SAGA in place is scheduled for Thursday, 18
October.


SI's


Below are brief summaries of what has happened to the SI over the past weeks.
In future reports I plan to add details.

AST (Astrometry Team) continues to work on understanding the FGS performance
and problems.  As stated above there is a general perception now that the FGS
problems are not just a matter of fine tuning.  Recent analyses have also
suggested that spacecraft jitter is not the fundamental FGS problem.  The
Astrometry team is also looking into the impact of these problems on their
science program.  A new proposal is being developed specifically to assess
this issue.

FOC got off to a quick start after my last report with a number of SAO/ERO
observations (see above).  This was followed by a number of instrument tests.
In general all is going well for the FOC.

FOS has had a busy three weeks, significantly advanced instrument readiness.
The current schedule has the first FOS SAO observation scheduled for the week
of 22 October.  One significant problem was discovered in FOS:  the Blue side
has a magnetic shielding problem similar to what was found for the Red side
but significantly smaller, ~25% of what was
found on the Red side.  FOS is currently spending a lot of time doing aperture
alignments without a lot of success at the moment but all the problems
encountered appear to be well understood and should not significantly impact
the first SAO observation.

GHRS has also had a busy three weeks.  The most significant event was their
first spectrum: the Hg-rich chemically peculiar star chi Lup.  The proposal was
designed to test how the aberrated image impacts spectral resolution.  The LSA
(Large Science Aperture) data was excellent but, unfortunately, the SSA (Small
Science Aperture) data (this aperture images directly onto one diode so
resolution is uneffected by image size) was lost because of a software problem.
Recently (yesterday) the GHRS looked at xi Per, specifically looking at
interstellar lines.  In this case data was obtained in both the LSA and SSA but
the star was not centered in either aperture.  Adequate data was obtained to
suggest (preliminarily) that deconvolution of LSA data gives a good match to
the SSA data.

HSP (High Speed Photometer) ran a number of instrument test these past weeks.
The only significant event was a decision to defer testing of the PMT
(Photomultiplier Tube), VIS, and POL detectors until
modifications to the bright earth avoidance angles are resolved.

WFPC has been active with the SAO/ERO observations discussed above and with
observing (or attempting to observe) the sun through the UV Flood light path.
The SAO/ERO observations were generally successful and the solar guiding
attempt went well: the sun was detected but at the edge of the scan pattern,
an error of ~0.5 degree.  This error was larger than desired but not a
surprise.

               Ron Polidan

      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 24 Oct 90 05:37:39 GMT
From: uvaarpa!murdoch!hudson.acc.Virginia.EDU![e-mail]  (Cameron 'Dale' Bass)
Subject: Re: NAVY WITHOLDING EVIDENCE!!!


   Shhhh....  Don't tell or the Air Force will want some too.

                                     dale bass
--
C. R. Bass                                           [e-mail]
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            [phone]

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

Date: 22 Oct 90 15:54:43 GMT
From: usc!cs.utexas.edu!helios![e-mail]  (Chris Duhon)
Subject: Re: Galileo Update - 10/19/90

In article <[e-mail]> [e-mail] (Ron Baalke) writes:
>
>                          GALILEO STATUS REPORT
>                            October 19, 1990
>
>     A NO-OP command was sent on October 15 to reset the Command Loss Timer
>to 264 hours, the planned value for this mission phase.
   *   *   *
>All actions were successfully completed and a NO-OP command was sent to reset
>the Command Loss Timer to 216 hours, the planned value for this mission phase.

What is the "Command Loss Timer," and what is the significance of the
various "hours" it is set to during different mission phases?

thanks,
chris
--

| Chris J. Duhon                 |  [e-mail]
| Dept of Computer Science       |  [e-mail]
| Texas A&M University           |

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

Date: 23 Oct 90 00:44:39 GMT
From: psuvm![e-mail]  (Jenni Sheehey)
Subject: Re: Theories needed on life

In article <[e-mail]>, [e-mail] (Kevin D. Quitt) says:
>
>In article <[e-mail]> [e-mail] (Jenni
>Sheehey) writes:
>>It really *is* unlikely that anything even resembling *any* species
>>presently on earth would be found on another planet by chance...
>
>    Unless you actually have proof of this, please label it as opinion.

I was unaware that anyone was expressing anything else... I didn't
expect that anyone would think that I had been to other planets and
was expressing Truth...  =)
                                                   --Jenni
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------------------------------

Date: 23 Oct 90 11:41:41 GMT
From: world!ksr![e-mail]  (Chris Jones)
Subject: Re: planetary cartographic coordinates

In article <[e-mail]>, spgreg@venus (Greg Macrae) writes:
>
>Mercury is tide locked with the sun.  That is one side always faces the sun.
>I suspect that the prime meridian is defined the same as luna's, ie. it
>splits the hemisphere that faces the body to which it is tide locked.  Most
>small moons are tide locked to the planets they orbit, and the same system
>would provide a definitive measure even before the surface is mapped.  It is
>just conjecture on my part that this may account for many of the definitions
>you found.
>
Although scientists thought so until some time in the sixties, it is now known
that Mercury most definitely does not present a constant face to the sun.  Its
sidereal day, interestingly enough, is 2/3 the length of its year.  This leads
to some interesting things: Mercury has two hot poles, since there are two
areas (on opposite sides) of Mercury which alternate being subsolar at
perhelion.  Since Mercury's orbital eccentricity is so great (it orbits between
.30 and .47 AU), the heat received at perhelion vs. aphelion is noticeably
different (I suppose it has two cold poles, too, with cold being a relative
term).  Also, when Mariner 10 flew by Mercury three times, it did so using a
solar orbit whose period was two Mercury years, so it ended up photographing
the same side of the planet each pass.  (I recall reading a short story written
many years ago by Isaac Asimov which depended on the "fact" that Mercury had a
side which was constantly dark.  He penned a little epilogue which said,
basically, "Oh, well, and I wish we'd gotten it right the first time.)

As to your last point, even for moons which rotate and revolve at the same
rate, there's some leeway in picking the prime meridian due to libration (over
60% of the Earth's moon's surface can be seen from Earth, for instance, just
not all at once).
--
Chris Jones    [e-mail]    {world,uunet,harvard}!ksr!clj

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

End of SPACE Digest V12 #484
*******************