From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Galileo Update - 04/15/93
Organization: Jet Propulsion Laboratory
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Distribution: world
NNTP-Posting-Host: kelvin.jpl.nasa.gov
Keywords: Galileo, JPL
News-Software: VAX/VMS VNEWS 1.41    

Forwarded from Neal Ausman, Galileo Mission Director

                                GALILEO
                     MISSION DIRECTOR STATUS REPORT
                             POST-LAUNCH
                         April 9 - 15, 1993

SPACECRAFT

1.  On April 9, real-time commands were sent, as planned, to reacquire
celestial reference after completion of the Low Gain Antenna (LGA-2)
swing/Dual Drive Actuator (DDA) hammer activities.

2.  On April 9, the EJ-1 (Earth-Jupiter #1) sequence memory load was uplinked
to the spacecraft without incident.  This sequence covers spacecraft activity
from April 12, 1993 to June 14, 1993 and includes a window for the Radio Relay
Antenna (RRA) slew test on April 28, 1993.  The command loss timer was set to
11 days as a part of this sequence memory load.

3.  On April 12 and 15, a NO-OP command was sent to reset the command loss
timer to 264 hours, its planned value during this mission phase.

4.  On April 12, 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.

5.  On April 12, an Ultra-Stable Oscillator (USO) test was performed to verify
the health status of the USO and to collect gravitational red shift experiment
data; long term trend analysis is continuing.

6.  On April 14, a 40bps modulation index test was performed to determine the
optimal Signal-to-Noise Ratio (SNR) when transmitting at 40bps.  Preliminary
analysis of the data suggests that the present pre-launch selected modulation
index is near the optimal level.

7.  On April 15, cruise science Memory Readouts (MROs) were performed for the
Extreme Ultraviolet Spectrometer (EUV) and Magnetometer (MAG) instrument.
Preliminary analysis indicates the data was received properly.

8.  On April 15, a periodic RPM (Retro-Propulsion Module) 10-Newton thruster
flushing maintenance activity was performed; all 12 thrusters were flushed
during the activity.  Thruster performance throughout the activity was nominal.

9.  The AC/DC bus imbalance measurements have not exhibited significant
changes (greater than 25 DN) throughout this period.  The AC measurement reads
19 DN (4.3 volts).  The DC measurement reads 111 DN (12.9 volts).  These
measurements are consistent with the model developed by the AC/DC special
anomaly team.

10. The Spacecraft status as of April 15, 1993, is as follows:

       a)  System Power Margin -  60 watts
       b)  Spin Configuration - Dual-Spin
       c)  Spin Rate/Sensor - 3.15rpm/Star Scanner
       d)  Spacecraft Attitude is approximately 18 degrees
           off-sun (lagging) and 6 degrees off-earth (leading)
       e)  Downlink telemetry rate/antenna- 40bps(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 PWS,
           EUV, UVS, EPD, MAG, HIC, and DDS
       i)  Probe/RRH - powered off, temperatures within
           acceptable range
       j)  CMD Loss Timer Setting - 264 hours
           Time To Initiation - 260 hours


GDS (Ground Data Systems):

1.  Galileo participated in a second DSN (Deep Space Network) acceptance test
for the DSN Telemetry Phase 3 Upgrade on April 13, 1993, using CTA-21
(Compatibility Test Area 21).  The purpose of this test was to verify
the flow of Galileo telemetry data through the new Telemetry Group Controller
(TGC) and the Telemetry Channel Assembly (TCA).  The TGC/TCA is the replacement
for the current Telemetry Processing Assembly (TPA).  Seven different telemetry
rates were run for this test; all ran well on both the MTS (MCCC Telemetry
Subsystem) and the AMMOS MGDS V18.0 GIF with the exception of 10bps.  The
10bps rate had some trouble staying in lock; it appears the TGC/TCA was
not metering the data correctly.  Further comparisons between the MGDS and MTS
data from this test are being conducted. MVT (Mission Verification Test) of
the TGC/TCA system is expected to begin May 16, 1993.


TRAJECTORY

     As of noon Thursday, April 15, 1993, the Galileo Spacecraft trajectory
status was as follows:

	Distance from Earth         152,606,000 km (1.02 AU)
	Distance from Sun           277,519,800 km (1.86 AU)
	Heliocentric Speed          93,400 km per hour
	Distance from Jupiter       543,973,900 km
	Round Trip Light Time       17 minutes, 4 seconds


SPECIAL TOPIC

1.  As of April 15, 1993, a total of 70184 real-time commands have been
transmitted to Galileo since Launch.  Of these, 65076  were initiated in the
sequence design process and 5108 initiated in the real-time command process.
In the past week, 7 real time commands were transmitted: 6 were initiated in
the sequence design process and one initiated in the real time command process.
Major command activities included commands to reacquire celestial reference,
uplink the EJ-1 sequence memory load, and reset the command loss timer.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Being cynical never helps 
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | to correct the situation 
|_____|/  |_|/       |_____|/                     | and causes more aggravation
                                                  | instead.
