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Subject: SPACE Digest V11 #239

SPACE Digest                                     Volume 11 : Issue 239

Today's Topics:
             Pegasus launch is a success!
        Re: HST Image Status for 04/01/90 (Forwarded)
              Galileo Update - 04/09/90
                  Re: Skylab
           Payload Status for 04/05/90 (Forwarded)
           Payload Status for 04/09/90 (Forwarded)
        Re: O-rings and launching in cold weather
          Re: Recommendations on Telescope Purchase.
                  Re: Skylab
----------------------------------------------------------------------

Date: 5 Apr 90 19:58:51 GMT
From: skipper![e-mail]  (Mary Shafer (OFV))
Subject: Pegasus launch is a success!

The subject line says it all.

It dropped off the hooks at about 1208 PDT and ignited 5 _loooong_ seconds
later.  Performance was nominal.  Excitement was rampant.
--

Mary Shafer  [e-mail] or ames!skipper.dfrf.nasa.gov!shafer
         NASA Ames Dryden Flight Research Facility, Edwards, CA
                   Of course I don't speak for NASA

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

Date: 9 Apr 90 01:51:08 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: HST Image Status for 04/01/90 (Forwarded)

It seems to me there may already be someone at JPL or Goddard reading
this now who could pull the necessary levers to get some images
transferred to an anonymous FTP directory every so often.

If so, how about speaking up.

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

Date: 9 Apr 90 18:09:15 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Galileo Update - 04/09/90



                              GALILEO
                      MISSION STATUS REPORT
                           April 9, 1990

     The Galileo spacecraft is now 80,768,210 miles from the Earth,
13,725,620 miles from Venus and traveling at a heliocentric velocity of 79,790
miles per hour.  Round trip light time is 14 minutes, 22 seconds.

     Two SITURNS to lead the sun were successfully performed on April 2 and 5.
Spacecraft performance for these activities was as expected and without
incident.

     Continued periodic characterization tests were successfully performed for
selected telecommunications hardware elements. Command Detector Unit and radio
frequency subsystem element tests were completed on April 1 and April 2,
respectively to characterize receiver automatic gain control operation,
receiver tracking loop operation and command detector signal-to-noise ratio
performance.

     The tenth RPM thruster "flushing" activity was successfully performed on
April 6.  The activity flushed the Z, L and S thrusters only.  The P thrusters
were not flushed since they are used periodically to perform the SITURNS.
These activities were performed at 40 bps and consequently thruster temperature
profiles were not available due to the low telemetry sample rate. Successful
flushing was inferred from other spacecraft measurements/events, including
attitude control performance and thruster counts.

     The Energetic Particles Detector (EPD) instrument was powered on and
commanded from Sector 4 to Sector 0 on April 6 in preparation for the upcoming
Trajectory Course Maneuver (TCM-4A).  Contamination analysis has predicted
that Sector 0 is the minimum contamination position for the EPD.  As part of
this general EPD activity, an EPD Memory Read Out (MRO) was also performed.
After the MRO, the EPD was turned off.

     Memory readouts were successfully performed as planned on April 2, 5 and
6 to return cruise science data from the Extreme Ultraviolet (EUV),
Magnetometer (MAG) and Dust Detector (DDS) instruments.

     Three attitude control related tests were performed on April 2 and 3.
Tests consisted of collecting data to update calibration information for
accelerometers, gyros and spin bearing assembly drag torque.

     The DC bus voltage imbalance measurement was observed to have dropped
significantly during the Deep Space Network (DSN) non-tracking period from
end of track on March 30 to the beginning of track in the afternoon on April 1.
The observed drop was about 5 volts and tended to a more-balanced bus
condition.  The imbalance reading changed from 21.6 volts to about 16.5 volts.
Subsequent to the DC imbalance measurement drop, it has fluctuated between
about 16.5 and 17.5 volts. No spacecraft activities or power switching events
were executed from the stored sequence during the non-tracking periods; all
other spacecraft telemetry measurements were as expected. The AC bus voltage
imbalance measurement has remained relatively stable varying between 47.5 and
48.2 volts.

     Commands were sent on April 6 to modify the maneuver telemetry map to
include additional Retropropulsion Module (RPM) temperature and Attitude and
Articulation Control Subsystem (AACS) telemetry measurements to provide improve
system temperature and delta velocity performance visibility during the TCM-4A
maneuver.

     The TCM-4A sequence generation and command products were reviewed and
approved by the Project on April 5.  The first of the four maneuver portions
was transmitted on April 8.  The other three portions will be transmitted on
subsequent days April 9, 11 and 12.  TCM-4A will be executed from April 9 thru
12 and consist of four vector mode portions.  Each portion (a day's worth of
maneuver activity) will impart a delta velocity magnitude of about 6.18
meters/sec.  The maneuver will be performed using only the L-thrusters with
benign duty cycles.  A total of 6372 pulses will be used with a total estimated
fuel consumption of 23.2 kg.

     The DSN has completed elevation bearing inspections at the 70 meter
antenna at Goldstone, California (DSS-14), and inspection is in process at the
70 meter antenna at Madrid, Spain (DSS-63).  No problems have been reported
that would require additional antenna downtime.  There will be no impact to
TCM-4 tracking support if no additional problems are discovered.

     The DSN reports that Mission Readiness Test (MRT) on the 34 meter antenna
at Canberra, Australia (DSS-45), has qualified that station for support of
Galileo when X-band capability becomes available.

     The results of the S-band Delta DOR demonstrations on Galileo, carried
out in January and February, show that five of the seven events yielded very
good Very Large Baseline Interferometry (VLBI) data. The other two events were
lost due to a ground software change-of-day problem and the previously reported
spacecraft fault protection execution (entry into spacecraft safing on January
15, 1990). Lessons learned from this exercise will be incorporated into Earth
Gravity Assist (EGA) Navigation planning.

 Ron Baalke                       |    [e-mail]
 Jet Propulsion Lab  M/S 301-355  |    [e-mail]
 4800 Oak Grove Dr.               |
 Pasadena, CA 91109               |

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

Date: 9 Apr 90 20:27:42 GMT
From: shlump.nac.dec.com!skylab.enet.dec.com![e-mail]
Subject: Re: Skylab

The gadget that they were planning to save Skylab with was called the
TRS, Teleoperator
Retrieval System.  It was cancelled when it became clear that Skylab was
coming down
before the shuttle went up.  TRS would have been useful for other
things, possibly, as
well, but Skylab was its only real customer at the time.

Jeez but Skylab (and its controllers!) was neat...they reactivated it
after n years of inactivity, got the batteries charged and the gyros
running and gained some reasonable degree
of attitude control before it died.  It reported calmly on the way down
as the various
pieces of itself burned and died.  Its last message reported that the
solar wings had
detatched.  Sigh.

Burns Fisher (Note my node name in the usenet path!)
VMS DECwindows and Display PostScript
[e-mail]

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

Date: 9 Apr 90 21:59:29 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Payload Status for 04/05/90 (Forwarded)

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

Date: Mon, 9 Apr 90 12:21:39 PDT
From: ames!nasamail.nasa.gov!payload.projects







            Daily Status/KSC Payload Management and Operations 04-05-90.


            - STS-31R HST (at pad-B) -

            The HST confidence test was completed and battery charging
            was terminated on third shift today.  Battery charging will
            continue today following the completion of pad clear
            hazardous operations.


            - STS-35 ASTRO-1 (at OPF) -

            ASTRO closeout activities and experiment servicing were
            worked Wednesday and will continue today.


            - STS-40 SLS-1 (at 0&C) -

            Rack and floor installation into the module was started
            Wednesday and will continue today.


            - STS-42 IML-1 (at O&C) -

            Staging activities on the floor and racks 5 and 8 were
            worked on Wednesday.  Floor staging along with racks 3, 4,
            7, 8, and 9 staging operations are scheduled for today.


            - STS-45 (Atlas-1)-

            Flight trunnion installation was completed on Wednesday.
            Joint kit installation on frame 4 was also worked on
            Wednesday and will continue today.


            - STS-55 SL-D2 (at O&C) -

            Rack 12 staging activities will continue today.


            - HST M&R (at O&C) -

            Cable continuity and isolation will continue today.

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

Date: 9 Apr 90 22:21:16 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Payload Status for 04/09/90 (Forwarded)


            Daily Status/KSC Payload Management and Operations 04-09-90.


            - STS-31R HST (at pad-B) -

            HST closeouts were completed and the payload bay doors were
            closed for flight at 0630 hours Sunday.  Launch countdown
            support continues with the PCG to orbiter ivt occurring
            first shift today.


            - STS-35 ASTRO-1 (at OPF) -

            ASTRO closeout activities and experiment servicing are
            continuing today.


            - STS-40 SLS-1 (at 0&C) -

            Rack and floor installation into the module was active
            Friday and Saturday and will continue today.


            - STS-42 IML-1 (at O&C) -

            The experiment floor was transferred to level IV on
            Saturday.  Today module pyrell foam replacement along with
            racks 3, 8, 9, and 11 staging operations are scheduled to be
            worked.


            - STS-45 (Atlas-1)-

            Pallet to pallet mating was started Friday and will continue
            through second shift today.

            - STS-55 SL-D2 (at O&C) -

            Rack 12 staging activities will continue today.


            - HST M&R (at O&C) -

            ORUC cable installations will continue today.

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

Subject: Re: O-rings and launching in cold weather
Date: Mon, 9 Apr 90 9:42:01 MESZ
From: Joseph C. Pistritto <[e-mail]>
Mailer: Elm [revision: 64.9]

I'm looking at the little table here "Figure 10" in Feynman's
book which has a chart of the temperature and the O-ring
damage level reported.  Now while the 3 lowest temperature points
show damage, so do 3 higher temperature points.  Probably more
significantly, the flight with the most damage (51C) was at the
lowest temperature.  The thing that most impresses me about this
table though, is that, quite independently of the temperature,
the joint obviously wasn't working right.  How this basic defect
could go uncorrected for so long was STUNNING.  It's really
obvious that you don't put a material like rubber in a place where
you expect FLAMES to be burning it away.  So quite obviously there
was a more fundamental problem that was just glossed over for a
long time, and that was the critical failure, at least as much
as the decision to launch at a low temperature.  At that time of
the year, they could have waited a few days for higher temperature,
but they still would have had this problem of the rings burning,
which very well would have come down and nailed them on a future
flight, if not this one.
--
Joseph C. Pistritto ([e-mail] -or- cgch![e-mail])
 Ciba Geigy AG, R1241.1.01, Postfach CH4002, Basel, Switzerland
 Tel: [phone] (work) [phone] (home)   GMT+2hrs!

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

Date: 9 Apr 90 15:53:09 GMT
From: pasteur!helios.ee.lbl.gov!hellgate.utah.edu!cs.utexas.edu!uwm.edu!zaphod.mps.ohio-state.edu!mips!bridge2!jarthur![e-mail]  (John H. Kim)
Subject: Re: Recommendations on Telescope Purchase.


Mail didn't work.

In article <[e-mail]> [e-mail] (Peter A. Nardi (CompSci) <nardi@usna>) writes:
>
>    I'm interested in purchasing an 8" SCT telescope.  The
>two models I'm considering are from Meade (the 2080) and Celestron
>(the classic - 8).  Has anyone had any experience with these scopes,
>good or bad?  There's not much difference in price, so recommendations
>on quality of optics, drives, etc would be helpful.

Both _Sky and Telescope_ and _Astronoy_ do field tests of both
brands (and others) each year.  Check the library.  One thing
that has come up in sci.astro is to be prepared to test the
optics.  Many people have had to return a couple of scopes to
get one with better optics.  Both companies are very reasonable
with their return policies and will replace an "unacceptable"
scope without question (generally).  If you don't know how to
test your optics, learn, or better yet, find someone who does.
A good deal of equipment is often necessary to get a scope with
optics as good as the ads say (1/20 wave, diffraction limited,
etc), but I hear even the most basic tests will weed out the
worst scopes.  Post to sci.astro for suggestions on testing--
I don't know, I don't own a scope, I've just wanted one for
the last ten years.
--
John H. Kim
[e-mail]

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

Date: 9 Apr 90 15:59:42 GMT
From: snorkelwacker!usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Skylab

In article <[e-mail]> [e-mail] writes:
>        was there ever any real chance of saving Skylab?  I read once taht
>if the space shuttle had been a bit more advanced a little sooner, then
>they would have gone up to repair Skylab.  Wouldn't it have been worth it?

There was some chance of a Skylab rescue, and in fact for a while it was
planned to be on the second shuttle flight.  Unfortunately, Skylab came
down earlier than expected and the shuttle flew later than expected.

As to whether it would have been worth it... somewhat of an open question.
The thing wasn't really designed for re-use; in particular, there were no
major provisions for resupply or repair in space, and it would have needed
both to be an operational station again.

>        And, on a related note, are the Soviets simply going to de-orbit
>Salyut 7 like they do all the progress modules?

Probably.  It will actually be a bit trickier than that, because they no
longer have good control over it; they'll have to send something up to
get it.  On the other hand, they've done that sort of thing before.
--
Apollo @ 8yrs: one small step.|     Henry Spencer at U of Toronto Zoology
Space station @ 8yrs:        .| uunet!attcan!utzoo!henry [e-mail]

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

End of SPACE Digest V11 #239
*******************