baalke@mars.jpl.nasa.gov (Ron Baalke) (11/10/90)
GALILEO STATUS REPORT
November 9, 1990
As of noon (PST) Thursday, November 8, 1990, the Galileo spacecraft is
15,401,300 miles from the Earth and traveling at a heliocentric speed of
58,380 miles per hour; distance to the Sun is 104,470,860 miles (1.11 AU).
The spacecraft is spinning at 2.89 rpm with a spacecraft attitude sun point
angle of 4.9 degrees. Round trip light time is 2 minutes, 50 seconds.
A special NO-OP command was successfully sent on November 2 using the
26-meter antenna in Spain to demonstrate command capability in the event
contingency backup 26-meter commanding is required during the Earth Flyby.
Another NO-OP command was sent on November 5, as planned, to reset the
Command Loss Timer to 216 hours, the planned value for this mission phase.
A MAG (Magnetometer) instrument cruise science Memory Readout (MRO) was
successfully performed on November 5; a planned EUV (Extreme Ultraviolet
Spectrometer) MRO on November 8 was lost.
Commands were sent on November 5 to enable the thruster firing all clear
algorithm allowing the PPR (Photopolarimiter Radiometer) and PLS (Plasma)
instruments to be in a state to collect data when powered on later in the
sequence, i.e., PPR covers open and PLS high voltages on.
Commands were also sent on November 5 to load a series of Delayed-Action
Commands (DACs) scheduled for execution on November 7 and November 13. The
commands will be used to cycle the RCT/NIMS (Near Infrared Mapping
Spectrometer) heaters off/on and RTG Boom Heaters on/off. Powering off the
RCT/NIMS is required to preclude possible radiative induced overheating of the
SSI (Solid State Imaging) detector during scan platform high cone slews
associated with UVS (Ultraviolet Spectrometer) data collection. Turning on
the RTG Boom heaters is required to minimize heat flow into the RPM (Retro
Propulsion Module) tanks. Proper command execution was verified for the
November 7 set of DACs.
Two more delta DOR (Differential One-way Ranging) activities were
completed on November 6. Both delta DORs were successful. The 70 meter
Goldstone/Australia pass was the first activity where link performance allowed
simultaneous transmission of spacecraft telemetry data along with DOR tone
modulation. A total of 19 of the planned 27 delta DOR activities are complete;
15 were successful.
The PWS (Plasma Wave), PLS and EPD (Energetic Particles Detector)
instruments were powered-on November 8. Telemetry received shortly after PLS
and EPD power turn on differed from predicted levels. Status of both
instruments has been assessed by the Principal Investigators and is not
considered to be a concern.
The PLS temperatures were observed to exceed predicted levels.
Consequently, non-interactive commands were sent to improve ground visibility
into the state of PLS detectors. Subsequent data analysis indicated no
concern for the PLS. The PLS temperatures are on a downward trend approaching
predicted steady state levels. One of the EPD LEMMS detectors exhibited higher
than expected noise counts at its lowest threshold setting. A non-interactive
command was sent to increase the threshold setting to collect important
detector status information. The cause of the increased noise counts is under
investigation. Preliminary results indicate no concern for the health of the
detector.
For some selected periods the spacecraft's telemetry downlink data rate
was commanded to 7.68 kbps via the stored sequence. This was the first time
since Venus flyby that this data rate has been used and successfully
processed by the ground data system.
The AC bus imbalance measurement remained relatively stable. The AC
measurement fluctuated about 2DN and is stable near 48.6 volts. The DC
measurement fluctuated about 100 DN (11 volts) during a period of no
spacecraft activity and is near 5 volts. All other power-related and
spacecraft telemetry measurements are normal.
The Project reviewed and approved the final cruise plan sequence products
for VE-12 (Venus-Earth 12) on November 5. This sequence controls spacecraft
events from December 17, 1990 to February 18, 1991. The Project also reviewed
and approved the final sequence and command generation products for the VE-11
Earth encounter sequence; Earth closest approach is on December 8.
The Project reviewed and approved the TCM-7 (Trajectory Course Maneuver-7)
design. This maneuver will be executed on November 13, and will use the axial
and lateral thrusters.
___ _____ ___
/_ /| /____/ \ /_ /|
| | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov
___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov
/___| | | | ___/ | |/__ /| M/S 301-355 |
|_____|/ |_|/ |_____|/ Pasadena, CA 91109 |