From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Galileo Update - 04/17/92
News-Software: VAX/VMS VNEWS 1.3-4   
Keywords:  Galileo, JPL
Reply-To: baalke@kelvin.jpl.nasa.gov
Organization: Jet Propulsion Laboratory
Date: Sat, 18 Apr 1992 01:03:20 GMT

Forwarded from Neal Ausman, Galileo Mission Director

                                  GALILEO
                      MISSION DIRECTOR STATUS REPORT
                                POST-LAUNCH
                           April 10 - 16, 1992

SPACECRAFT

1.  On April 10, as part of the Cooling Turn No. 6 activities, the S-band TWTA
(Traveling Wave Tube Amplifier) was commanded to the high power mode and
spacecraft telemetry was processed for approximately 2 1/4 hours indicating the
spacecraft is operating normally.

2.  On April 13, as part of Cooling Turn No. 6 activities, the S-Band TWTA was
again commanded to the high power mode and spacecraft telemetry was processed
for approximately 3 hours. The RCT-NIMS (Near Infrared Mapping Spectrometer)
nickel transducer telemetry indication went into alarm (255 DN) at 1839 UTC
and remained there until loss of telemetry.  After the sun acquisition on
April 16, the RCT-NIMS nickel transducer telemetry initially read 201 DN and
then went into alarm (255 DN).  This behavior is characteristic of a
temperature transducer failure.

3.  The pre-cool portion of Cooling Turn No. 6 was completed on April 13.
The spacecraft bus cool down behaved similar to Cooling Turn No. 5.  The turn
to 165 degrees off sun was initiated on April 13 at 2123 UTC.  The spacecraft
downlink carrier was lost at 2206 UTC due to a ground station hardware problem
which was 16 minutes prior to the predicted carrier loss of lock (see Special
Topic No. 2).

4.  On April 16, after approximately 50 hours at the cooling attitude, the
spacecraft was commanded back to a 5 degree off-sun attitude.  The downlink
carrier was acquired at 0248 UTC and telemetry was received at 0327 UTC.  The
spacecraft return to a 5 degree off-sun attitude completed at approximately
0325 UTC.  After the sun acquisition, sun gate data was collected to determine
if an antenna rib is still obscuring the sun gate signal.  Data analysis
indicates that the sun gate is still obscured, indicating no ribs released
(see Special Topic No. 2).

5.  On April 16, a NO-OP command was sent to reset the command loss timer to
336 hours, its planned value for this mission phase.

6.  On April 16, as part of the Cooling Turn No. 6 activities, commands were
sent to checkout the Star Scanner (SS) shutter.  This activity is performed
after each HGA (High Gain Antenna) thermal turn as a precaution to protect the
star scanner from "seeing" bright particles which could have been released if
the HGA ribs released (see Special Topic No. 2).

7.  The AC/DC bus imbalance measurements exhibited some change.  The DC
measurement decreased 4 DN and reads 18.3 volts.  The AC measurement remained
unchanged and reads 2.9 volts.

8.  The Spacecraft status as of 1700 PDT April 16, 1992, is as follows:

       a)  System Power Margin -  22 watts
       b)  Spin Configuration - Dual-Spin
       c)  Spin Rate/Sensor - 3.14 rpm/Acquisition Sensor
       d)  Spacecraft Attitude is approximately 5 degrees off
           sun (leading)
       e)  Downlink telemetry rate/antenna-10 bps (coded)/LGA-1
       f)  General Thermal Control - all temperatures within
           acceptable range
       g)  RPM Tank Pressures - all within acceptable range
       h)  Orbiter Science- EUV, DDS, MAG, UVS, EPD, and HIC are
           powered on
       i)  Probe/RRH - powered off, temperatures within
           acceptable range
       j)  CMD Loss Timer Setting - 336 hours
           Time To Initiation - 335 hours


UPLINK GENERATION/COMMAND REVIEW AND APPROVAL:

1.  The EE-6/7 (Earth-Earth 6 & 7) Final Cruise Profile Design was approved by
the Project on April 15, 1992.  This sequence controls spacecraft activities
from May 11, 1992 to November 23, 1992.

2.  The Earth/Moon-2 Encounter Cruise Activity Plan (CAP) was approved by the
Project on April 16, 1992.  This plan includes spacecraft activities from
November 23, 1992 to January 4, 1993.

GDS (Ground Data Systems):

1.  The Integrated Software Functional Diagram (ISFD) document was published
April 13, 1992.  This update to the ISFD documents changed or updated software
interfaces and provides the most recent validation dates for all interfaces.
The ISFD describes, in both textual and diagram form the interfaces, the
functional flow of these interfaces, and the program sets using these
interfaces.  Included in this document is a short description of each Software
Interface Specification (SIS) and a listing of all GLL SISs, the receiving and
supplying program sets. The ISFD is updated periodically.  The next planned
update is scheduled for October 1992.

2.  The  April System Engineer's Monthly Report (SEMR) was conducted Monday,
April 13.  A review of current Project and Institutional system (MOSO & DSN)
status was conducted.  Pre-Earth 2 delivery schedules, past months
accomplishments and potential problem areas were discussed.  No major problems
or concerns were reported.

TRAJECTORY

     As of noon Thursday, April 16, 1992, the Galileo Spacecraft trajectory
status was as follows:

        Distance from Earth          253,366,000 miles (2.73 AU)
        Distance from Sun            200,350,000 miles (2.16 AU)
        Heliocentric Speed           36,400 miles per hour
        Distance from Jupiter        692,209,000 miles
        Round Trip Light Time        45 minutes, 28 seconds

SPECIAL TOPICS

1.  As of April 16, 1992, a total of 7732 real-time commands have been
transmitted to Galileo since Launch.  Of these, 2973  were pre-planned in the
sequence design and 4759 were not.  In the past week, 43 real time commands
were transmitted; 43 were pre-planned in the sequence design.  In addition,
3999 mini-sequence commands have been transmitted since March 1991; (1748
were pre-planned and 2251 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 and checkout the Star Scanner (SS)
shutter.

2.  The Cooling Turn No. 6 activities are scheduled from April 6 to April 17.
The spacecraft bus cool down period started on April 6 and completed on
April 13.  The cooling turn was performed on April 13 and the spacecraft
remained at the cooling attitude for approximately 50 hours.  The spacecraft
return from the cooling attitude occurred on April 16.  The sun gate and
wobble ID data collection is scheduled during the April 16-17 time period.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Denial is always the first
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | sympton.
|_____|/  |_|/       |_____|/                     |