NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/sci/space/16180

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From: [e-mail] (Ron Baalke)
Subject: Galileo Update - 11/20/92
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Date: Sat, 21 Nov 1992 03:40:35 GMT
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Forwarded from Neal Ausman, Galileo Mission Director

                                 GALILEO
                      MISSION DIRECTOR STATUS REPORT
                               POST-LAUNCH
                          November 12 - 19, 1992

SPACECRAFT

1.  On November 13, the Trajectory Correction Maneuver (TCM-16) was performed
on the spacecraft.  The maneuver used the spacecraft's lateral thrusters to
impart a predicted total delta velocity of 0.89 m/s.  This maneuver was
executed at 1200 bps with the spacecraft pointed approximately 7 degrees off
the Sun.

     The spacecraft's performance throughout the activity was nominal. All
RPM (Retro-Propulsion Module) pressures and temperatures and attitude control
indicators were near predicted levels.  After the lateral burn segment, the
sequence planned pointing correction was executed; the sequence planned spin
correction was not needed.

2.  On November 14, after completion of TCM-16, the Energetic Particle Detector
(EPD) instrument was moved from Sector O (TCM safe position) to Sector 5 and
scanning operation initiated to continue science data collection.  The science
scanning mode continued until November 17 at which time the EPD was moved to
Sector 4 and the motor turned off.  The EPD instrument is continuing to
collect science data in Sector 4.

3.  On November 14 and 15, delta Differenced One-Way range (DOR) passes were
performed over DSS-14/63 (Goldstone/Madrid) and DSS-14/43 (Goldstone/Canberra).
Initial results indicate the four delta DOR passes were successfully performed.

4.  On November 16, a periodic RPM 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.

5.  On November 16, the spacecraft performed a 13 degree SITURN.  The purpose
of the SITURN was to maintain the spacecraft within plus or minus 10 degrees
of the sun at the current solar distance.  Real-time commands were also sent to
change the downlink telemetry format back to the Low Rate Science (7.68 kbps)
from the Engineering High Rate 1200bps (automatically selected in the maneuver
PA) to collect a unique near-Earth magnetosphere data.

6.  On November 16, the Earth vector and Earth stars were updated to the
spacecraft's current attitude.  This change implements the attitude maintenance
strategy required in the case of an AACS (Attitude and Articulation Control
Subsystem) POR (Power-On Reset).  If a fault occurs which terminates the
currently executing sequence, the spacecraft will maintain its current
attitude.

7.  On November 17, the Relay Radio Hardware (RRH) oscillators No. 1 and 2
were powered on in preparation for the Probe Mission Sequence Test (MST)
scheduled for November 20, 1992.  Shortly after turn on the oscillator
temperatures increased to expected values.

8.  On November 18, real-time commands were sent to turn the Ultraviolet
Spectrometer (UVS) instrument on, load and readout the UVS memory, and start
the UVS microprocessor.  Three memory readouts of the UVS load were completed
and verified prior to turning the UVS microprocessor on. The instrument was
then configured to a nominal state with the master high voltage disabled,
G-channel selected, and the grating stepping.  The UVS is now properly
configured for the start of EE-9 (Earth-Earth 9 sequence). The UVS
supplemental heater was turned off to complete the activity.

9.  On November 19, real-time commands were sent to increase the telemetry
rate from 7.68 kbps to 28.8 kbps in preparation for the Probe Mission Sequence
Test (MST) on the following day.  Additionally, Delayed Action Commands (DACs)
were sent to turn ranging off and two-way non-coherent (TWNC) on prior to the
MST and reconfigure to ranging on and TWNC off after the MST completes.  These
actions were taken to optimize telecommunications performance during the Probe
MST.

10. The AC/DC bus imbalance measurements exhibited some change. The AC
measurement has ranged from 15DN to 17DN and now reads 15DN (3.5 volts).
The DC measurement has ranged from 134DN (15.7 volts) to 142DN (16.7 volts)
and now reads 142DN (16.7 volts).  These measurement variations are consistent
with the model developed by the AC/DC special anomaly team.

11. The Spacecraft status as of November 19, 1992, is as follows:

       a)  System Power Margin -  80 watts
       b)  Spin Configuration - Dual-Spin
       c)  Spin Rate/Sensor - 3.15rpm/Star Scanner
       d)  Spacecraft Attitude is approximately 6 degree
           off-sun (leading) and 16 degrees off-earth (lagging)
       e)  Downlink telemetry rate/antenna-28.8kbps (coded)/LGA-1
       f)  General Thermal Control - all temperatures within
           acceptable range
       g)  RPM Tank Pressures - all within acceptable range
       h)  Orbiter Science- PWS, PLS, UVS, EPD, MAG, HIC and DDS
           are powered on
       i)  Probe/RRH - RRH oscillators powered on, temperatures
           within acceptable range
       j)  CMD Loss Timer Setting - 264 hours
           Time To Initiation - 260 hours


UPLINK GENERATION/COMMAND REVIEW AND APPROVAL:

1.  The EE-12 Final Profile Design Product was approved by the Project on
November 13.  This sequence covers spacecraft activities from January 20, 1993
to January 23, 1993 and from February 8, 1993 to April 12, 1993.

2.  The EE-11 Preliminary Sequence and Command Generation products were
approved by the Project on November 17.  This sequence covers spacecraft
activities from December 7 to December 28, 1992 including the Earth 2 closest
approach on December 8.

3.  The EE-9 Final Sequence and Command Generation package was approved for
transmission by the Project on November 19, 1992.  This sequence covers
spacecraft activities from November 23, 1992 to December 5, 1992.  The
sequence is scheduled to be sent to the spacecraft on November 21.

GDS (Ground Data Systems):

1.  A second SPC-60 (Madrid Signal Processing Center) Telemetry Data Flow test
was conducted on Monday, November 16.  The test was successful in establishing
a configuration for the Probe checkouts.  This configuration utilized two
Type A TPA's (Telemetry Processing Assemblies) in parallel, one configured to
the 56K full duplex line and one configured to the 224kbps Simplex line, with
Area Routing Assembly (ARA-1) as Prime and ARA-2 as backup.  The only drop-outs
with this configuration were associated with "line hits" and were recoverable
on ARA ODR (Original Data Recording) replays. The test also successfully
demonstrated the configuration to be used to support 134.4 kbps High Rate
science at Earth 2.  As a result of an excellent effort by DSN (Deep Space
Network) and SPC-60 personnel, data dropouts have been minimal this week.


TRAJECTORY

     As of noon Thursday, November 19, 1992, the Galileo Spacecraft trajectory
status was as follows:

    Distance from Earth         14,931,800 km (.10 AU)
    Distance from Sun           161,989,800 km (1.08 AU)
    Heliocentric Speed          118,300 km per hour
    Distance from Jupiter       912,828,500 km
    Round Trip Light Time       1 minute, 38 seconds


SPECIAL TOPIC


1.  As of November 19, 1992, a total of 8684 real-time commands have been
transmitted to Galileo since Launch.  Of these, 3660  were initiated in the
sequence design process and 5024 initiated in the real-time command process.
In the past week, 35 real time commands were transmitted: none were initiated
in the sequence design process and 35 initiated in the real time command
process.  Major command activities this week included commands to reconfigure
the downlink telemetry data rate to 7.68 kbps, turn the UVS instrument on and
configure it for science data collection, turn the UVS supplemental heater off,
switch the telemetry rate to 28.8 kbps, and configure ranging and the TWNC for
the probe MST.

2.  A training rehearsal for the GOPEX experiment operations was successfully
completed November 18th.  The rehearsal was supported by elements of the
Galileo Flight Team (MCT, NAV, and SDT), DSN Ops Team and GOPEX operations
Team at Table Mountain Observatory (TMO) and Kirtland AFB.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Learn to recognize the
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | inconsequential, then
|_____|/  |_|/       |_____|/                     | ignore it.