From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Galileo Update #2 - 09/11/92
Followup-To: sci.space
News-Software: VAX/VMS VNEWS 1.3-4   
Keywords:  Galileo, JPL
Reply-To: baalke@kelvin.jpl.nasa.gov
Organization: Jet Propulsion Laboratory
Date: Sat, 12 Sep 1992 05:09:14 GMT

Forwarded from Neal Ausman, Galileo Mission Director

                                 GALILEO
                     MISSION DIRECTOR STATUS REPORT
                               POST-LAUNCH
                        September 4 - 10, 1992

SPACECRAFT

1.  On September 8, realtime commands were sent to change the System Fault
Protection (SFP) AACS-INIT (Attitude and Articulation Control Subsystem)
pointing slot from the Earth to the Sun prior to the Dual Drive Actuator
(DDA) No. 3 pulse activities.  This change will allow the spacecraft to
return to a sun-pointed attitude if an AACS Power on Reset (POR) occurs
during the DDA No. 3 pulse activities (see Special Topic No. 2).

2.  On September 8, the DDA pulse mini-sequence memory load went active.
The warming turn to a 45-degree off-sun attitude commenced at approximately
1536 UTC and completed at 1608 UTC.  The first of two motor turn on pulses
occurred at 1826 UTC for approximately two seconds, as planned.  The DDA
motor temperature was approximately minus 12 degrees C at turn on.  The DDA
motor current data analysis is in progress.

3.  On September 9, after approximately 28 hours at the warming attitude, the
second motor turn on pulse occurred at 1916 UTC for approximately two seconds,
as planned.  The DDA motor temperature was approximately plus 9 degrees C at
turn on.  DDA motor current data playback completed at approximately 1921 UTC
on September 10 and data analysis is in progress.  Additionally, the
spacecraft, under stored sequence control, was commanded back to a six degree
off-sun attitude at approximately 1923 UTC.  After the sun acquisition, sun
gate data was collected to determine if an antenna rib is still obscuring the
sun gate signal.  Preliminary data analysis indicates that the sun gate is
still obscured, indicating no ribs released; analysis is continuing.

4.  The AC/DC bus imbalance measurements exhibited some change.  The AC
measurement remained unchanged and reads 3.3 volts. The DC measurement has
ranged from 120 DN (14.0 volts) to 140 DN (16.4 volts) and now reads 129 DN
(15.1 volts).  These measurement variations are consistent with the model
developed by the AC/DC special anomaly team.

5.  The Spacecraft status as of September 10, 1992, is as follows:

       a)  System Power Margin -  68 watts
       b)  Spin Configuration - Dual-Spin
       c)  Spin Rate/Sensor - 3.14rpm/Acquisition Sensor
       d)  Spacecraft Attitude is approximately 5 degrees
           off-sun (leading)
       e)  Downlink telemetry rate/antenna-40 bps (coded)/LGA-1
       f)  General Thermal Control - all temperatures within
           acceptable range
       g)  RPM Tank Pressures - all within acceptable range
       h)  Orbiter Science- UVS, EUV, DDS, MAG, EPD, and HIC are
           powered on
       i)  Probe/RRH - powered off, temperatures within
           acceptable range
       j)  CMD Loss Timer Setting - 264 hours
           Time To Initiation - 206 hours


TRAJECTORY

     As of noon Thursday, September 10, 1992, the Galileo Spacecraft
trajectory status was as follows:

	Distance from Earth         64,280,500 miles (.69 AU)
	Distance from Sun           141,694,300 miles (1.53 AU)
	Heliocentric Speed           55,100 miles per hour
	Distance from Jupiter        642,944,800 miles
	Round Trip Light Time        11 minutes, 38 seconds


SPECIAL TOPIC

1.  As of September 10, 1992, a total of 8114 real-time commands have been
transmitted to Galileo since Launch.  Of these, 3236  were pre-planned in
the sequence design and 4878 were not.  In the past week, 1 real time command
was transmitted and pre-planned in the sequence design.  In addition, 5677
mini-sequence commands have been transmitted since March 1991; 3519 were
pre-planned and 2158 were not.  In the past week, no mini-sequence commands
were transmitted.  Major command activities this week included commands to
change a System Fault Protection parameter.

2.  The Dual Drive Actuator (DDA) pulse mini-sequence No. 3 covers spacecraft
activities from September 8 to 11, 1992.  The warming turn to a 45-degree
off-sun attitude along with the first DDA two second motor turn on pulse
occurred on September 8.  The spacecraft remained at the warming attitude for
approximately 28 hours.  The second DDA two second motor turn on pulse
occurred just prior to turning back to approximately a 6 degree off-sun
attitude.  Sun gate data was collected on September 10.  The star scanner
checkout along with the collection of wobble data is scheduled for
September 11.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Anything is impossible if
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you don't attempt it.
|_____|/  |_|/       |_____|/                     | 

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