From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Mars Observer Update - 09/25/92 (Launch Day)
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: Sat, 26 Sep 1992 09:23:57 GMT

                         MARS OBSERVER STATUS REPORT
                                 Launch Day
                            September 25, 1992

     The Mars Observer spacecraft was launched today after a 38 minute delay.
At 17:05:01 UTC, the Titan III solid rocket boosters burst to life and
leaped off the launch pad at a 98 degree flight azimuth.  The Titan III
then proceeded to to deliver Mars Observer into Earth orbit.  At one minute,
48 seconds after launch (+01:48), the Titan core vehicle ignited, as planned,
and could easily be verified with the long range cameras tracking the launch.
This was quickly followed by the solid rocket booster jettision at +01:56.
At +04:28, the second stage on the Titan ignited and the first stage
separation then followed.  The second stage continued to burn until
it shutdown at +08:05, as planned.  A trim velocity burn started at +09:22
and continued for 36 seconds.  In less than 10 minutes, Mars Observer was now
in an Earth parking orbit.  At +15:00, the Titan III separated from Mars
Observer.  The Titan III had completed its part of the launch effort
flawlessly.

    The next step at this point was that the two ARIA planes supporting
the launch were to acquire the S-band signal from the TOS (Transfer Orbit
Stage) upper stage.  After several minutes, neither plane reported receiving
any signal from TOS.  Did something happen?  Did the TOS malfunction, or was
it still functioning properly, but was just not transmitting any telemetry
back to Earth?  We did not know.  This was the maiden flight of the TOS, and
some doubts began to creep forth.  At +39:51, the TOS was to ignite its solid
rocket boosters to send Mars Observer from an Earth parking orbit onto a
trajectory to Mars.  The time came and went, and still no signal from TOS.
We don't know if the burn occured or not, or if the spacecraft was still in
Earth orbit.  At +51:03, DSS-46 (26 meter antenna at Canberra) was in position
to acquire the TOS signal.  Still more silence from TOS.  Then a report came
in that the ARIA planes visually saw a red glow in the sky at the time that
the TOS burn was to have occured, and this was encouraging news.  At +53:31,
the Mars Observer spacecraft was scheduled to separate from the TOS, but we
could not confirm this without any feedback from TOS.  The TOS was then
scheduled to perform a small delta burn at +57:31 to move itself away from
the spacecraft.  Still no signal acquisition from TOS.  Canberra was scheduled
to acquire the X-band downlink from Mars Observer at +01:24:00, but that was
still a good 30 minutes away at this point.  We just had to sit and wait.

     Three of the Canberra antennas were being used to acquire Mars Observer's
signal.  We brought up the Canberra's telemetry displays on our monitors.
What Canberra saw, we would see at the same time here at JPL.  We waited
for +01:24:00 to arrive.  As +01:11:30 went by, Mars Observer was supposed to
deploy its High Gain Antenna, solar arrays and Magnetometer.  Fifteen more
minutes to go.  Since I've worked on the telemetry subsystem being used for
Mars Observer, I was very familiar with all of the fields on the displays
what they meant.  The displays were showing red "OUT-OF-LOCKs", and if we get
a signal from Mars Observer then they would turn to green "IN-LOCKs".
As +01:24:00 approached, we could hear the commentary on NASA Select
mentioning that they were waiting for confirmation of spacecraft acquisition
from Canberra.  We all turned our eyes to the displays waiting for our
telemetry subsystem to acquire a signal from Mars Observer.  Then the DSA
field on the display went to a green IN-LOCK followed quickly by green IN-LOCKs
in the Frame Synchronizer and Reed Solomon fields.  We've acquired the signal
from the spacecraft!  The DSA SNR (signal-to-noise ratio) was over 20 with
the Reed Solomon SNR at 40.  We were receiving a strong and clean signal.
TOS has done its job.  Word of the signal acquisition was quickly relayed to
Kennedy Space Center, and we watched the mission controllers celebrate on
NASA Select.  Mars Observer was OK and on its way to Mars.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     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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            Robert K. Rouse		rkrouse@netcom.com
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