From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Galileo Update #2 - 08/27/92
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: Fri, 28 Aug 1992 05:48:25 GMT

Forwarded from Neal Ausman, Galileo Mission Director

                                   GALILEO
                      MISSION DIRECTOR STATUS REPORT
                                 POST-LAUNCH
                            August 21 - 27, 1992

SPACECRAFT

1.  On August 24, a NO-OP command was sent to reset the command loss timer
to 264 hours, its planned value for this mission phase.

2.  On August 26, a periodic RPM (Retro-Propulsion Module) 10-Newton thruster
maintenance activity was performed; 10 of the 12 thrusters were "flushed"
during the activity.  The P-thrusters were not flushed because they were used
to perform science turn (SITURN) activities on the same day.  Spacecraft
performance throughout the activity was normal.

3.  On August 26, the spacecraft performed a 16.5-degree SITURN.  The purpose
of this SITURN is to maintain the spacecraft within a plus or minus 10
degrees of the sun while within a solar distance of 1.6 AU.

4.  On August 26, the Earth vector and Earth stars were updated to the
spacecraft's present attitude.  This strategy is being employed such that if
spacecraft safing is invoked, the spacecraft will remain at the current
attitude instead of going to sun point.  This will expedite spacecraft
recovery in the event of spacecraft safing.

5.  On August 26, cruise science Memory Readouts (MROs) were performed for
the Extreme Ultraviolet Spectrometer (EUV), Dust Detector (DDS), and
Magnetometer (MAG) instruments.  Preliminary analysis indicates the data
was received properly.

6.  On August 27, an Ultra-Stable Oscillator (USO) test was performed to
verify the health status of the USO and collect gravitational red shift
experiment data; long term trend analysis is continuing.

7.  During the period of August 26 through August 27, a navigation cycle was
performed.  This navigation cycle provided near-continuous acquisition of
two-way doppler and ranging data during three consecutive passes of the
spacecraft over DSS-14, DSS-43, and DSS-63.  This data will improve orbit
determination in preparation for the TCM-15 (Trajectory Correction
Maneuver #15) scheduled for October 9.

8.  The AC/DC bus imbalance measurements exhibited some change. The AC
measurement increased 1 DN and reads 3.3 volts. The DC measurement has
ranged from 121 DN (14.1 volts) to 130 DN (15.2 volts) and now reads 130 DN
(15.2 volts).  These measurement variations are consistent with the model
developed by the AC/DC special anomaly team.

9.  The Spacecraft status as of August 27, 1992, is as follows:

       a)  System Power Margin -  69 watts
       b)  Spin Configuration - Dual-Spin
       c)  Spin Rate/Sensor - 3.15rpm/Star Scanner
       d)  Spacecraft Attitude is approximately 10 degrees
           off-sun (leading) and 24 degrees off-earth (lagging)
       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 - 184 hours

TRAJECTORY

     As of noon Thursday, August 27, 1992, the Galileo Spacecraft trajectory
status was as follows:

	Distance from Earth         80,355,100 miles (.87 AU)
	Distance from Sun           149,427,100 miles (1.61 AU)
	Heliocentric Speed           52,300 miles per hour
	Distance from Jupiter        652,523,900 miles
	Round Trip Light Time        14 minutes, 32 seconds


SPECIAL TOPIC

1.  As of August 27, 1992, a total of 8111 real-time commands have been
transmitted to Galileo since Launch.  Of these, 3233  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, 5427
mini-sequence commands have been transmitted since March 1991; 3269 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
reset the command loss timer.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Optimists live longer
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | than pessimists.
|_____|/  |_|/       |_____|/                     | 

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