From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Mars Observer Update - 09/28/92
Followup-To: sci.space
News-Software: VAX/VMS VNEWS 1.3-4   
Keywords:  Mars Observer, JPL, KSC
Reply-To: baalke@kelvin.jpl.nasa.gov
Organization: Jet Propulsion Laboratory
Date: Tue, 29 Sep 1992 08:06:19 GMT

Forwarded from Glenn Cunningham, Mars Observer Deputy Project Manager

                         MARS OBSERVER
                        OPERATIONS STATUS
                September 28, 1992 at 8:00 AM PDT

During the early part of the past week, Mars Observer made good
progress toward launch.  The battery management during countdown
was developed and tested.  TOS (Transfer Orbit Stage) continued to
work on understanding the anomalous gyro reading observed during
the Launch Day Dress Rehearsal and concluded it was a normal
response to motions induced from moving the Mobile Service Tower.
Titan worked off a problem with a leaking battery cell, and a
problem with destruct system initiators.

Spacecraft power turn-on for launch, normally scheduled at L-24
hours, was delayed because Titan was behind schedule on L-1 day.

The spacecraft executed a normal countdown sequence with no
anomalies.  The Titan countdown was delayed by two power failures
in the Vehicle Integration Building (VIB) where the Titan is
controlled, and by delays in clearing personnel from the pad.
During a good portion of the latter hours of the countdown, two
factors in the weather criteria for launch were red.  In
addition, the predictions for a nitrogen tetroxide toxic plume of
greater than 5 parts per million to drift off the Federal
property in the event of a near-pad destruct of the Titan, caused
a potential launch hold for most of the morning.  Upper level
winds also restricted the launch azimuth to less than 105 degree
which reduced the two hour launch window to one hour and 41
minutes.

Finally, at 17:05:01.496 on Friday, September 25, 1992, 38
minutes into the window, Mars Observer was launched.

The Titan performance as monitored by the down-range stations,
was good.  However, the Advanced Range Instrumentation Aircraft
(ARIA) did not receive the Transfer Orbit Stage (TOS) S-band
carrier or telemetry, although a bright light (presumably the TOS
solid motor burn) was observed during the proper interval.  The
Canberra DSN (Deep Space Network) stations, acquired the spacecraft's
X-band signal on schedule.

When the spacecraft was acquired, the solar array was properly
deployed, but the High Gain Antenna was not completely deployed.
The HGA telemetry deployment indication was received about five
and a half hours later, indicating that the boom was slow to
deploy.  When the boom apparently latched, the attitude control
system lost its star reference, and transferred to a waiting
mode.  Ground commands on Saturday night restored attitude
control to the proper mode - Array Normal Spin.

Temperatures of two of the science instruments, MOC (Mars Observer
Camera) and PMIRR (Pressure Modulator Infrared Radiometer),
were low requiring heaters to be turned on.

The first cruise sequence was loaded Sunday morning, and started
execution at 9:00 AM Sunday.  All events are occurring properly.

During launch, the TOS telemetry data is recorded on the
spacecraft's recorders.  Unfortunately, playback of the recorder
yesterday did not yield any data.

The trans-Mars orbit injection appears to be about 1.8 sigma
after two days of tracking data.

The second part of the first cruise sequence will be loaded on
schedule today.  This sequence will extend the Magnetometer and
Gamma Ray Spectrometer booms to their cruise position on Tuesday.

The spacecraft and the mission operations system both appear to
be working in fine order.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Quiet people aren't the
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | only ones who don't say
|_____|/  |_|/       |_____|/                     | much.

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