From: baalke@kelvin.Jpl.Nasa.Gov (Ron Baalke)
Subject: Galileo Update - 01/08/93
To: sci-space-news@ames.arc.nasa.gov
Followup-To: sci.space
News-Software: VAX/VMS VNEWS 1.41    
Keywords: Galileo, JPL
Organization: Jet Propulsion Laboratory
Date: Sat, 9 Jan 1993 18:24:00 GMT

Forwarded from Neal Ausman, Galileo Mission Director

                               GALILEO
                   MISSION DIRECTOR STATUS REPORT
                             POST-LAUNCH
                 December 18, 1992 - January 7, 1993

SPACECRAFT

1.  On December 18, real-time commands were sent to disable the system fault
protection thruster flushing all clear response.  With the Plasma Detector
(PLS) and the Photopolarimeter-Radiometer (PPR) instruments being turned off,
the thruster flushing all clear response was no longer needed and was disabled
to eliminate unnecessary PPR heater cycles which would otherwise occur during
thruster firing activities.

2.  On December 18, real-time commands were sent to enable the Plasma Detector
(PLS) science alarm monitor after it had tripped on November 28 when the PLS
temperature exceeded 35 degrees C.  This monitor was reset in order for it to
be functional for the next PLS instrument on time.

3.  On December 18, Delayed Action Commands (DACs) were sent to turn the
S-Band ranging on December 19 which is the original background state of EE-11
(Earth-Earth #11 sequence).

4.  On December 18, the playback of the Earth/Moon conjunction movie was
completed.  This playback consisted of a 14-hour period showing the Moon
passing by as the Earth slowly rotated beneath it.  All the data was received
and processed on the ground.

5.  On December 18, 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 SITURN activities on December 16.  Spacecraft activity throughout
the period was normal.

6.  On December 21, a NO-OP command was sent to reset the command loss timer
to 264 hours, its planned value during this mission phase.

7.  On December 22, the Dual Drive Actuator (DDA-5) Turn A sequence memory load
was uplinked to the spacecraft without incident.  This sequence covered
spacecraft activities from December 28, 1992 to January 4, 1993 and included a
DDA windup/hammer window opportunity on December 29-30 for approximately 20
hours (see Special Topic No. 2).

8.  On December 22, real-time commands were sent to set the command loss timer
to 96 hours.  NO-OP commands were sent on December 24 and 26 to reset the
command loss timer to 96 hours, its planned value during this mission phase.

9.  On December 28, as part of the DDA-5 Turn A sequence activities, the
warming turn to a 45-degree off-sun attitude started at approximately
1816 UTC and completed at 1854 UTC.  After turn completion, real-time commands
were sent to modify the Retro-Propulsion Module (RPM) thermal safing response.
Also, real-time commands were sent to modify the attitude control Fault Monitor
(FM) 2 persistence level from two hours to 55 minutes (see Special Topic
No. 2).

10. On December 29, after approximately 20 hours at the warming attitude, the
DDA-5 windup/hammering activities commenced at 1455 UTC.  A total of 2160
hammer pulses were executed along with three 20 second windup sequences. Data
analysis indicated the ballscrew rotated approximately 360 degrees for a total
ballscrew rotation beginning with the initial deployment attempt of
approximately 6.4 rotations.  There was no indication of a rib release
(see Special Topic No. 2).

11. On December 30, the spacecraft, under stored sequence control, was
commanded back to a 5 degree off-sun attitude at approximately 1048 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 field of view is still obscured although
the signature appears to have changed.  Initial analysis indicates that rib
No. 2 may have moved out to a 43 degree angle.  Also, preliminary results may
indicate that the antenna mesh is covering the sun gate field of view.

     Additionally, real-time commands were sent to open the star scanner (SS)
shutter, reacquire celestial reference, and select scan type 6 to perform
precise wobble estimation.  The wobble estimate indicated a change of 0.3
milliradians which collaborated the motor current data indicating that no
ribs released (see Special Topic No. 2).

12. On December 30, real-time commands were sent to set the command loss timer
to 144 hours, its planned value for this mission phase.  On January 4, NO-OP
commands were sent to reset the command loss timer to 144 hours.

13. On January 4, a periodic RPM 10-N thruster maintenance activity was
performed; 10 of the 12 thrusters were "flushed" during the activity.  The
P-thrusters were not "flushed" because they are being used during the DDA-5
turn sequence activities.  Spacecraft activity throughout the period was
nominal.

14. On January 4, the Dual Drive Actuator (DDA-5) Turn B sequence memory load
was uplinked to the spacecraft without incident.  This load set the command
loss timer to 120 hours.  This sequence covers spacecraft activities from
January 5, 1993 to January 8, 1993 and includes DDA windup/hammer window
opportunities throughout the period (see Special Topic No. 3).

15. On January 5, as part of the DDA-5 Turn B sequence activities, the warming
turn to a 34-degree off-sun attitude started at approximately 2001 UTC and
completed at 2026 UTC.  After the turn completion, real-time commands were
sent to modify the Retro-Propulsion Module (RPM) thermal safing response in
the event of sequence termination.  Specifically, the change included turning
the external shunt heaters and bus distribution 2 heaters on while turning off
the NIMS (Near Infrared Mapping Spectrometer) shield heater and despun heaters.

     After approximately two hours at the warming attitude, hammering of the
HGA (High Gain Antenna) motors commenced.  Five 180 hammer pulse sequences
were sent beginning at 2225 UTC and ending at 0442 UTC.  The motor hammering
sequences were executed with the HGA motor temperature at 19.3 degrees C,
29.8 degrees C, 34.4 degrees C, 36.2 degrees C, and 40.6 degrees C.
Preliminary analysis indicated that the ballscrew was stalled with no
appreciable ballscrew rotation.  There was some suggestion of minor rotation
with the HGA motor temperature at 29.8 degrees C.  There was no indication of
a rib release (see Special Topic No. 3).

16. On January 6, HGA motor hammering started at 1800 UTC.  Two 180 hammer
pulse sequences were sent and the activity completed at 1958 UTC.  These motor
hammering sequences were executed with the HGA motor temperature at 47.2
degrees C.  Data analysis is in process (see Special Topic No. 3).

17. On January 7, two 180 hammer pulse sequences were sent while the HGA
motor temperature was at 47.2 degrees C.  Data analysis is in process
(see Special Topic No. 3).

18. The AC/DC bus imbalance measurements exhibited some change. The AC
measurement has ranged from 16DN to 19DN and now reads 18DN (4.1 volts).
The DC measurement has ranged from 62DN (6.9 volts) to 157DN (18.5 volts) and
now reads 150DN (17.7 volts).  These measurement variations are consistent
with the model developed by the AC/DC special anomaly team.

19. The Spacecraft status as of January 7, 1993, is as follows:

         a)  System Power Margin -  16 watts
         b)  Spin Configuration - All-Spin
         c)  Spin Rate/Sensor - 2.9 rpm/Acquisition Sensor
         d)  Spacecraft Attitude is approximately 32 degrees
             off-sun (leading) and 41 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- Instruments powered on are the EUV,
             EPD, MAG, HIC, and DDS
         i)  Probe/RRH - powered off, temperatures within
             acceptable range
         j)  CMD Loss Timer Setting - 120 hours
             Time To Initiation - 118 hours


UPLINK GENERATION/COMMAND REVIEW AND APPROVAL:

1.  The Dual Drive Actuator (DDA)-5 Part B sequence memory load was approved
for transmission by the Project on December 30, 1992.  This sequence covers
High Gain Antenna (HGA) motor windup/hammering activities from January 5, 1993
through January 8, 1993.  Individual sets of hammering/windup commands were
approved as required immediately prior to being uplinked to the spacecraft.

2.  The Dual Drive Actuator (DDA-5) Part C sequence memory load was approved
for transmission by the Project on January 7, 1993.  This sequence covers
High Gain Antenna (HGA) motor windup/hammering activities from January 11,
1993 to January 14, 1993.  As with previous windup/hammering activities,
individual sets of hammering/windup commands will be approved as required
prior to being uplinked to the spacecraft.


GDS:

1.  A Galileo MVT (Mission Verification Test) was performed on
December 20, 1992, from 00:00:00 to 05:00:00 GMT, using DSS-12 (Goldstone
34 meter antenna).  The purpose of the test was to evaluate the new Station
Communications Processor's (SCP) ability to support Galileo.  This test
exercised telemetry, monitor, and command for Galileo.  All telemetry rates
were to be tested, however due to resource and time constraints only two rates
were successfully run, (134.4 kbps HRW and 40 bps ESS [uncoded]).  The SCP
worked well for the two telemetry rates, monitor, and nominal command portions
of the MVT.  Galileo will run all remaining telemetry data rates through the
new SCP interface before any demo passes and/or the SCP is placed in SOAK.
The next available date for a SCP MVT is January 14, 1993.


TRAJECTORY

     As of noon Thursday, January 7, 1993, the Galileo Spacecraft trajectory
status was as follows:

	Distance from Earth         22,107,500 km (0.15 AU)
	Distance from Sun           156,587,900 km (1.05 AU)
	Heliocentric Speed          135,300 km per hour
	Distance from Jupiter       772,250,300 km
	Round Trip Light Time       2 minutes, 30 seconds


SPECIAL TOPIC

1.  As of January 7, 1993, a total of 25059 real-time commands have been
transmitted to Galileo since Launch.  Of these, 20010  were initiated in the
sequence design process and 5049 initiated in the real-time command process.
In the past three weeks, 16244 real time commands were transmitted: 16242 were
initiated in the sequence design process and 2 initiated in the real time
command process.  Major command activities included commands to modify system
fault protection response, enable science alarm monitor, turn S-Band ranging
on, reset the command loss timer, uplink DDA-5A sequence memory load, modify
attitude control fault monitor persistence level, windup and hammer the HGA,
open the star scanner shutter, reacquire celestial reference and select scan
Type 6.

2.  The Dual Drive Actuator (DDA) pulse mini-sequence No. 5A covered spacecraft
activities from December 28, 1992 to January 4, 1993.  The warming turn to a
45-degree off-sun attitude occurred on December 28.  The spacecraft remained at
the warming attitude for approximately 40 hours.  The motor windup/hammering
activities began approximately 20 hours at the warming attitude and continued
for 20 hours.  A total of 2160 hammer pulses were executed along with three 20
second windup sequences.  The sun acquisition back to approximately a 5-degree
off-sun attitude occurred on December 30.  Sun gate data was collected on
December 30.  The star scanner checkout along with collection of wobble data
was conducted on December 30.

3.  The Dual Drive Actuator (DDA) pulse mini-sequence No. 5B covers spacecraft
activities from January 5, 1993 to January 8, 1993.  The warming turn to a
34-degree off-sun attitude occurred on January 5, 1993.  The spacecraft will
remain at this warming attitude until January 11, 1993 at which time DDA pulse
mini-sequence No. 5C is scheduled to begin.  The motor windup/hammering
activities began approximately two hours after reaching the warming attitude.
A total of ten 180 pulse motor hammering sequences are scheduled which will
execute 1800 motor hammering pulses on the spacecraft.  The star scanner
checkout along with collection of wobble data is scheduled for January 8, 1993.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life. 

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