Cassini Significant Event Report

For Week Ending 12/04/98

Spacecraft Status:


The most recent Spacecraft status is from the DSN tracking pass on
Thursday, 12/03, over the Madrid tracking station. The Cassini spacecraft
is in an excellent state of health and is executing the Cruise 11 sequence
normally. The speed of the spacecraft can be viewed on the
"Where is Cassini Now?"
web page (http://saturn.jpl.nasa.gov/operations/present-position.cfm).


Spacecraft Activity Summary:


On Saturday, 11/28, the Solid State Recorder (SSR-B) record and playback
pointers were reset as planned (nominally once per week).


On Tuesday, 12/01, the Propulsion Module Subsystem (PMS) was successfully
pressurized in preparation for Wednesday's Deep Space Maneuver (DSM).


On Wednesday, 12/02, the Deep Space Maneuver, a large maneuver required to
shape the spacecraft trajectory to achieve the proper energy gain from the
next Venus flyby, was sucessfully uplinked and executed. Nominal maneuver
size was 449.97 m/s and was expected to take approximately 87 minutes to
complete.


Maneuver activities began with a series of commands to reconfigure
spacecraft heaters for the main engine burn. The next set of spacecraft
activities was commands to open the cover for the main engine. After
spacecraft telemetry confirmed that the cover had been successfully
opened, a ground command was sent to activate the main engine burn
sequence. The S/C first performed roll and yaw turns to reach the desired
burn attitude. The main engine burn began slightly after 10:00 PM PST and
completed 87 minutes 35 seconds later. The S/C then re-oriented itself to
the nominal sun-point attitude, closed the main engine cover, and
reconfigured for the nominal cruise state.


All S/C telemetry and radiometric data indicate that the maneuver was
extremely successful. S/C carrier signal was tracked by the DSN throughout
the maneuver. Burn time was within 1% of the nominal value, all propulsion
system parameters were within expected ranges, and the attitude control
system reports an excellent maneuver. Continued tracking by the DSN will
provide data for an updated navigation solution to be made available on
Dec. 5.


On Thursday, 12/03, three activities occurred. The VIMS Decontamination
Heaters were powered up for a 24 hour period, the AACS High Watermarks
were cleared, and routine maintenance was performed on the Solid State
Recorder (SSR-B) flight software partitions.


Upcoming events:


Activities scheduled for the week of 12/04-12/10 include data playback
from the DSM and an SSR Pointer Reset on 12/04, Propulsion Module
Subsystem isolation on 12/05, uplink of the C11 Sequence Part II and
Stellar Reference Unit calibration on 12/07, AACS High Watermark Clear on
12/08, and IVP Vector Update and Mass Properties Update on 12/10.



Additional information about Cassini-Huygens is online at http://saturn.jpl.nasa.gov.


Cassini will begin orbiting Saturn on July 1, 2004, and release its piggybacked Huygens probe about six months later for descent through the thick atmosphere of the moon Titan. Cassini-Huygens is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Office of Space Science, Washington, D.C.


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