From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Galileo Update - 12/18/92
News-Software: VAX/VMS VNEWS 1.3-4   
Keywords:  Galileo, JPL
Reply-To: baalke@kelvin.jpl.nasa.gov
Organization: Jet Propulsion Laboratory
Date: Sat, 19 Dec 1992 01:12:13 GMT

Forwarded from Neal Ausman, Galileo Mission Director

                                   GALILEO
                      MISSION DIRECTOR STATUS REPORT
                                POST-LAUNCH
                          December 11 - 17, 1992
         *************************************************************
                   Merry Christmas and Happy New Year!!

         Because of the Christmas Holiday, the Mission Director Report
         will not be published next week.  The next report will be on
         January 7, 1992.

         *************************************************************

SPACECRAFT

1.  On December 11, real-time commands were sent to turn ranging off in order
to maximize the downlink telemetry performance for the science instrument
calibration activities scheduled later in the day.

2.  On December 12, real-time commands were sent to zero out the Bright Body
Avoidance (BBA) vector onboard the spacecraft.  This vector was causing the
star scanner shutter to close sooner than expected resulting in infrequent
dropouts of the first star in a two star set.  This action was taken to
eliminate the possibility of the star dropouts increasing and causing SEQID
to fail which in turn would have caused the gyros to be selected as the
primary attitude source and would have adversely effected scan platform
priority and the possibility of tripping gyro fault protection.

3.  On December 12, real-time commands were sent to turn Two-Way Noncoherent
(TWNC) on prior to the sequence controlled Extreme Ultraviolet Spectrometer
(EUV)/Ultraviolet Spectrometer (UVS) cross calibration activity.

4.  On December 13, the spacecraft went through perihelion at a solar distance
of .982 AU.  All spacecraft temperatures were near predicted levels.

5.  On December 14, a NO-OP command was sent to reset the command loss timer
to 264 hours, its planned value during this mission phase.

6.  On December 14, a routine sun vector update was performed.  This sun
vector is valid until December 31, 1992.

7.  On December 15, real-time commands were sent to disable the attitude
control bright body avoidance fault protection after the completion of the
Earth 2 flyby.

8.  On December 15, real-time commands were sent to turn the TWNC off prior
to the SITURN on December 16 in order to receive two-way doppler data for
navigation purposes.

9.  On December 16, the spacecraft executed a 14-degree SITURN which brought
the cone angle down from approximately 95 degrees to 83 degrees.  Subsequently,
the telecommunication performance improved prior to the Earth/Moon conjunction
movie playback beginning on December 17 and continuing into December 19.

10. On December 16, the Galileo Optical Communications Experiment from an
Earth-based Xmitter (GOPEX) experiment was completed.  This experiment
consisted of pulsing a laser at the Galileo spacecraft from the Table Mountain
Observatory (TMO) and the Starfire Optical Range (SOR).  The Solid State
Imaging (SSI) camera was shuttered while slewing across the Earth resulting
in a series of illuminated pixels in the image.  Initial results indicate that
laser transmissions were successfully detected from both TMO and SOR.  Data
analysis is continuing.

11. On December 17, real-time commands were sent at the direction of the PI
(Principal Investigator) to turn the Plasma Detector (PLS) instrument off
approximately 31 hours before the stored sequence onboard the spacecraft
would have turned the instrument off.  The instrument temperature at turn off
was approximately 43.7 degrees C which was less than one degree below the
maximum waived temperature limit of 44.4 degrees C.

12. During the reporting period, numerous science instrument
calibrations/characterization activities were performed to take advantage of
the high telemetry data rates while close to the Earth.  Activities included
Near Infrared Mapping Spectrometer (NIMS) partial Photometric Calibration
Target (PCT) calibration, NIMS partial Radiometric Calibration Target (RCT)
calibration, Extreme Ultraviolet Spectrometer (EUV)/Ultraviolet Spectrometer
(UVS) cross calibration, EUV star calibration, UVS syscan, NIMS mirror scan
calibration, Plasma Wave (PWS) calibration, and Solid State Imaging (SSI)
partial PCT.  All calibration/characterization activities were performed
nominally and data analysis is in progress.

13. The AC/DC bus imbalance measurements exhibited some change. The AC
measurement has ranged from 13DN to 17DN and now reads 17DN (3.9 volts).
The DC measurement has ranged from 44DN (4.7 volts) to 157DN (18.5 volts) and
now reads 157DN (18.5 volts).  These measurement variations are consistent
with the model developed by the AC/DC special anomaly team.

14. The Spacecraft status as of December 17, 1992, is as follows:

       a)  System Power Margin -  79 watts
       b)  Spin Configuration - Dual-Spin
       c)  Spin Rate/Sensor - 3.15 rpm/Star Scanner
       d)  Spacecraft Attitude is approximately 6 degree
           off-sun (leading) and 83 degrees off-earth (leading)
       e)  Downlink telemetry rate/antenna- 1200bps(coded)/LGA-1
       f)  General Thermal Control - all temperatures within
           acceptable range
       g)  RPM Tank Pressures - all within acceptable range
       h)  Orbiter Science- all instruments are powered on
           except the PPR, NIMS, and PLS
       i)  Probe/RRH - powered off, temperatures within
           acceptable range
       j)  CMD Loss Timer Setting - 264 hours
           Time To Initiation - 240 hours


UPLINK GENERATION/COMMAND REVIEW AND APPROVAL:

1.  The EE-12 (Earth-Earth 12) Preliminary Sequence and Command Generation
products were approved by the Project on December 16, 1992.  This sequence
covers spacecraft activities from January 20, 1993 to January 23, 1993 and
from February 8, 1993 to April 12, 1993.

2.  The Dual Drive Actuator (DDA-5) Part A sequence memory load was approved
for transmission by the Project on December 17, 1992.  This sequence covers
High Gain Antenna (HGA) motor hammering activities from December 28, 1992
through January 4, 1993.  Part B of this sequence will be reviewed for
approval on December 30, 1992, subsequent parts of the overall DDA-5 sequence
will be reviewed and approved as needed after January 4, 1993.  The commands
for windup/hammering activities on December 29 and 30 were also reviewed.
Individual sets of hammering/windup commands will be approved as required
immediately prior to being uplinked to the spacecraft.


TRAJECTORY

     As of noon Thursday, December 17, 1992, the Galileo Spacecraft trajectory
status was as follows:

	Distance from Earth         6,928,300 km (.05 AU)
	Distance from Sun           147,267,200 km (0.99 AU)
	Heliocentric Speed          140,300 km per hour
	Distance from Jupiter       836,434,500 km
	Round Trip Light Time       0 minutes, 48 seconds

SPECIAL TOPIC

1.  As of December 17, 1992, a total of 8815 real-time commands have been
transmitted to Galileo since Launch.  Of these, 3768  were initiated in the
sequence design process and 5047 initiated in the real-time command
process.  In the past week, 29 real time commands were transmitted: 15 were
initiated in the sequence design process and 14 initiated in the real time
command process.  Major command activities this week included commands to
turn ranging off, zero out the bright body vector, turn the TWNC on, reset
the command loss timer, turn the TWNC off, disable the bright body avoidance
fault protection, and turn the PLS instrument off.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
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