Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V12_4/V12_487.TXT

Internet Message Format | 1991-06-28 | 16KB

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/cb9cPsG00VcJ4kuU54>;
          Thu, 25 Oct 1990 02:32:26 -0400 (EDT)
Message-ID: <[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Thu, 25 Oct 1990 02:31:22 -0400 (EDT)
Subject: SPACE Digest V12 #487

SPACE Digest                                     Volume 12 : Issue 487

Today's Topics:
                  Re: Pluto
              Re: Mammoth Magellan Data
             Re: Theories needed on life
           Hubble Space Telescope Update - 10/19/90
            Re: Pioneer 11 article

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: 22 Oct 90 19:37:47 GMT
From: comp.vuw.ac.nz![e-mail]  (Timothy Banks)
Subject: Re: Pluto

In article <[e-mail]> [e-mail] (Ron Baal

>I did a little further research on this.  In the 1990 Astronomical Almanac,
>page F2, it lists Pluto  of having a 94 degree orbital inclination to the
>planetary equator of 1950.  In the book called "Planets Beyond, Discovering
>the Outer Solar System",  1990 edition, page 296, Pluto is also listed as
>having a 94.0 degree inclination of equator to orbit.  However, in the
>"The New Solar System", 3rd edition, page 291, Charon is listed as having
>an orbital inclination of 98.8 degrees.
>

In Marciallis (_A.J_, 95(3), pp941, 1988) the Harrington and Christie
polynomial for Pluto's sub earth latitude is given as

                       jo = 106 (deg)
                       j = jo - ( 2.2 * T ) - ( 0.005 * T * T ) in deg
                       i = j + 1.8 * ( 2 * pi * ( t - 0.6 )) in deg

where j is the heliocentric inclination, i is the apparent geometric
inclination, T is the epoch measured from 1980.0, and t is the fractional
year. Buie and Tholen (1989) in their Figure 1 compare this polynomial
with the orbital calculation based on the satellite orbit of Tholen
and Buie, which shows that for around now the two methods are very close.

I hope that this might help with things! However, I stress that this is
not my field at all, and in now way is this meant as a slight. I have
great respect for Dr Tholen's work with Pluto, and enjoy Ron's postings
(Thanks Ron - keep the good work up).

--
------------
Timothy Banks, Physics Department, Victoria University of Wellington, NZ.
[e-mail];[e-mail];[e-mail].
"He's dead, Jim!" "OK, you take the tricorder - I'll take the wallet!"

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

Date: 22 Oct 90 18:56:45 GMT
From: mojo![e-mail]  (Doug Mohney)
Subject: Re: Mammoth Magellan Data

In article <[e-mail]>, [e-mail] (Ron Baalke) writes:
>In article <[e-mail]> [e-mail] writes:
>>A graph on a nearby wall states that around March 1991, the
>>data returned from Magellan will exceed that returned by all
>>other planetary probes combined (pushing 1 trillion bits).
>>
>>Hmm, let's see, ftp'ing over a 56kbaud link...  :-)

Sounds like a good idea for pushing FDDI and other fast goodies on a national
scale.

>The Magellan data will be stored on 60+ CD-ROMs.  One CD-ROM holds
>680 megabytes of data.  This is only after 8 months of mapping.  Then when
>you include the extended mission....

Yes, but do K-tel or DAK industries have the rights to distribute them? :-)

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

Date: 22 Oct 90 03:04:56 GMT
From: van-bc!ubc-cs!news-server.csri.toronto.edu!utgpu!cunews!cognos!dgbt!rick.doc.ca!calvin.doc.ca![e-mail]  (Andrew Patrick)
Subject: Re: Theories needed on life

In article <[e-mail]> [e-mail] (Clayton Cramer) writes:
>In article <[e-mail]>, [e-mail] writes:
>> Could someone theorize on what humanoid life would be like on a planet 3 or 4
>> times the size of the Earth.  I'm looking for theories on body structure,
>> societies, technology, psychology, etc.  Thanks, I appreciate any speculation.
>>
>>                     dml
>
>Short.  Squat.  Massive limbs.  Leg bones of tremendous density and
>thickness.  Massive muscles to move those heavy and strong bones.
>Enormous calorie requirement to operate those bodies.  A great fear
>of heights. :-)

Sounds like a dinasour.  Hum... I wonder if there is a new theory here
somewhere.   Is the earth shrinking in size?  Perhaps the earth was
much larger and when it shrunk the dinosaurs perished or simply
slipped from the gravitational pull.  My son has always wondered why
they were so big!

Lotsa :-)'s

--
Andrew Patrick, Ph.D.       Department of Communications, Ottawa, CANADA
               [e-mail]    [e-mail]
        HDTV:  higher resolution, improved colour, wider screen,
            "sit-com" reruns.  What's wrong with this picture?

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

Date: 24 Oct 90 01:11:50 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Hubble Space Telescope Update - 10/19/90

The following is forwared from Ron Polidan, astronomer on the HST team
------------------------------------------------------------------------
                               HST Status Report
                               October 19, 1990

Current Status and Summary

All has not gone well with the SAGA (Solar Array Gain Augmentation) software on
HST.  It does appear that the software has greatly reduced the 0.1 Hz
oscillation produced by the solar arrays but it apparently was forcing the
gyros into "high mode" much more frequently than desired.  The SAGA is
currently disabled.  Testing of the SAGA software will continue to gather
additional data but it seems unlikely that this software will be kept on the
spacecraft in its present form.  Since my last report a week ago the Astrometry
team has been using the FGS's (Fine Guidance Sensors) to their first SAO
(Science Assessment Observation) -- Duplicity Among Hyades Stars, with mixed
results, GHRS (Goddard High Resolution Spectrograph) attempted to get an SAO
observation of alpha Tau, but observation was unsuccessful due to a failure of
the FGS's to acquire guide stars (incorrect guide star thresholds).  The rest
of the time HST was performing various SI (Scientific Instrument) tests,
these, in general, went well.


PCS (Pointing Control Subsystem)

The goal of the SAGA software was to remove the oscillations seen in the HST
pointing that are produced by thermal gradients warping the SPA's (Solar Power
Arrays).  Testing of the SAGA involved enabling and disabling it for periods of
time and followed by comparative analyses of performance.  The installation
went rather smoothly.  After a few days of testing a number of things became
clear.  First, the SAGA was very successful in removing the 0.1 Hz disturbance;
the estimate was a factor of 30 reduction in amplitude.  With this disturbance
gone the other oscillation frequencies known to exist in the data (ranging from
~0.3 to 0.6 Hz) were more visible but not amplified.  Unfortunately, the SAGA
was frequently forcing the gyros out of the "low mode" state necessary for
science operation and into a "high mode" state.  With the gyros in the high
mode state there there is also a probability of a safing event.  The frequency
of gyro high mode transitions was high enough to make it clear that the SAGA
fix will have to be reexamined.  In the course of the SAGA testing it was
discovered that  one part of the SAGA software, a torque limiting package, was
not disabled when the rest of the SAGA was turned off.  It was also noted that
with the SAGA off some gyro problems were still occurring, suggesting that the
torque limiter was part of the problem.  It was then discovered that the while
the torque limiting software could not be fully disabled it could be "patched"
to effectively remove it form the system.  This was quickly done and the gyro
problems disappeared.  At the moment plans are to continue testing of the SAGA
but in a manner that will have minimum impact of other HST operations.
Discussions and analyses are continuing but it appears unlikely that the
current SAGA software will be kept on the spacecraft.  It will probably be at
least next week (pending the test schedule) before we have some
definitive statements on the SAGA and its problems.  Nothing new with regards
to the FHST's (Fixed Head Star Trackers) or the FGS's since my last report.


HST Focusing and Image Quality

Nothing fundamentally new here since mid-September.  A few revised numbers:
the primary mirror conic constant: values range from -1.0145 to -1.0125 and
appear to be converging.  Error in the field lens: 1.33 +/- 0.05.


ERO (Early Release Observations) and SAO Programs

Two new SAO/ERO observations were attempted over the past week: the Astrometry
team proposal looking at "Duplicity Among Hyades Stars" and a GHRS team
proposal studying the "Chromosphere of Alpha Tauri."   The Astrometry proposal
is the second of three runs, the final run is scheduled for the SMS (Science
Mission Specification) beginning on 29 October.  At this early stage in the
proposal the only comment that has been made is that "results are mixed."  The
results of the GHRS alpha Tau proposal were much less than "mixed" -- no data
on alpha Tau was obtained.  No guide stars were acquired and the star was never
placed in the instrument aperture.  It appears that incorrect FGS thresholds
for the acquisition were in the SMS.  This proposal will be rescheduled.
Nothing additional on any of the earlier SAO/ERO observations.  (Remember
beginning with this next report I will list only new SAO/ERO observations or
updates on old observations reported in earlier Status Reports.)  Below is a
list of the recent SAO/ERO observations and those planned in the next two
weeks.


AST (Astrometry Team):

   o Duplicity Among the Hyades (SAO) -- first two parts completed (no
     assessment), final run scheduled for the week of 29 October.

   o Orbital Parameters of Known Binaries -- scheduled for the week of 29
     October.


FOC (Faint Object Camera):

   o No new observations or results.


FOS (Faint Object Spectrograph):

   o Imaging of NGC 1566 with the PC (SAO) -- scheduled for 27 October.

   o Helium in the Early Universe (target UM 675) (SAO) -- scheduled for 28
     October (this is the first FOS instrument SAO/ERO observation).

   o Red Side Spectrophotometry of NGC 1068 -- scheduled for the week of 29
     October.


GHRS:

   o Chromosphere of Alpha Tau -- Failed, no guide stars (will be rescheduled)

   o Circumstellar Matter Around Beta Pictoris -- scheduled for 23 October


HSP (High Speed Photometer):

   o No new observations.


WFPC (Wide Field/Planetary Camera):

   o No new observations or results.


SMS's

All is going reasonably well.  Most activity in the current SMS's was directed
toward the SAGA installation and testing.  Beginning Monday (22 October) we
begin an SMS that contains OTA (Optical Telescope Assembly) image
characterization, an FOC mini-sweep image characterization and the HARP
(Hubble Aberration Recovery Program) proposal for further characterization of
the WFPC.  Also included in this SMS are FOC, FOS, and HSP instrument testing,
the GHRS SAO observation of Beta Pic, and an OTA mini-OFAD (Optical Field
Angle Distortion) proposal.  The following SMS (29 October) has more SI
testing, AST and FOS SAO/ERO observations, more FOC mini-sweep image
characterization, a desorption monitoring proposal, and a WFPC UV
Flood guiding test.


SI's

There is a pointing problem that is affecting all SI's to some degree.  It
appears that there is an uncertainty in the pointing accuracy of HST with
respect to the SI apertures/field-of views.  The size of the uncertainty is 2-4
arc seconds, a rather large error compared to most of the apertures.  The
belief is that the origin of the error is in the poor FGS to FGS alignment.  A
new FGS to FGS alignment is scheduled for the week of 5 November.  Reanalysis
of earlier (poor) data is also in progress -- a bug was found in the earlier
reduction software.

AST continues to work on understanding the FGS performance and problems.  They
have developed a "9 Points of Light" proposal (scheduled for the day 323, 26
November SMS) that does a detailed investigation of focal positions within a
given FGS pickle and allows intercomparison of all three FGS pickles.

FOC continues to function well with essentially no instrument problems.

FOS has obtained their first external spectrum (Red Side) and, except for the
magnetic shielding problems, have no significant instrument anomalies.

GHRS is the most advanced of the SI in terms of OV/SV proposals completed with
all of their OV proposals and some SV proposals finished.  Unfortunately, the
same cannot be said for their SAO/ERO observations, none of those attempted
have been fully successful (see above and my previous report).

HSP is advancing instrument testing with the exception of the PMT, VIS, and POL
detectors until modifications to the bright earth avoidance angles are
resolved.

WFPC has been relatively quiet recently -- no major instrument problems have
been reported.

     Ron Polidan

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

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

Date: 23 Oct 90 22:20:03 GMT
From: mnetor!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Pioneer 11 article

In article <[e-mail]> [e-mail] (Daniel Mocsny) writes:
>1. What was the original design life of the spacecraft?

Long enough to get to Saturn, which was maybe five years.  (Don't remember.)

>2. Since the end of their primary missions, how valuable has been
>the data returned by the Pioneers and Voyagers?
>
>3. In particular, have these "used spacecraft" been instrumental in
>major discoveries after the ends of their primary missions?

The data has been useful but not Earth-shaking.  The single most prominent
result is fairly strong negative evidence that there is no major tenth
planet.  (The effects on the Pioneer/Voyager trajectories would have been
seen by now.)  The big news will be hitting the heliopause (the boundary
of the Sun's atmosphere), but the Voyagers are likely to get there first.

>4. As the RTG's run down and transmission distances grow, how long
>can NASA realistically hope to maintain useful contact with these
>craft? ...

The limiting factor for both the Pioneers and the Voyagers is the lifetime
of the RTGs.  Barring failures, the Pioneers will be in touch for about
another decade and the Voyagers for about another three.  Improvements in
communications and such have helped ensure that that isn't the bottleneck.

>5. I know we can't predict discoveries, but would anyone care to
>take a stab at what we're going to lose by Pioneer 11 biting the
>(star)dust?

*Probably* nothing massive.  But as you observe, the big discoveries are
the things you can't predict.  That side, the main loss will be fields-
and-particles data from a region that won't be visited again for a long
time.

>6. How come NASA let the primary contractor get away with no
>field service contract? ;-) I mean, I recently saw an ad from
>TRW service, saying they "do it all"!

I believe the contract specified depot service only, with the customer
responsible for bringing it in. :-)
--
The type syntax for C is essentially   | Henry Spencer at U of Toronto Zoology
unparsable.             --Rob Pike     |  [e-mail]   utzoo!henry

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

End of SPACE Digest V12 #487
*******************