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Significant Event Report for Week Ending 12/5/1997

MSO Significant Events input for week of Friday 11/28 through Thursday 12/04:

Spacecraft Status:

Most recent Spacecraft status is from the DSN tracking pass on Thursday, 12/04, over Madrid.

The Cassini spacecraft is in an excellent state of health and is operating nominally. The C5 sequence continues to execute onboard the spacecraft. Early-cruise spacecraft configuration activities are nearly complete.

Inertial attitude control is being maintained using the spacecraft's hydrazine thrusters (RCS system). The spacecraft continues flying in a High Gain Antenna-to-Sun attitude. It will maintain the HGA-to-Sun attitude, except for needed trajectory correction maneuvers, for the first 14 months of flight.

Communication with Earth during early cruise is via one of the spacecraft's two low-gain antennas; the antenna selected depends on the relative geometry of the Sun, Earth and the spacecraft.

Spacecraft Activity Summary:

The 28-day Magnetospheric Imaging Instrument (MIMI) decontamination activity, begun on 11/21, continued nominally through the week.

On Friday, 11/28, there were no changes in spacecraft configuration.

On Saturday, 11/29, the SSR record and playback pointers were reset, according to plan. This housekeeping activity, done approximately weekly, maximizes the amount of time that recorded engineering data is available for playback to the ground should an anomaly occur on the spacecraft.

From Sunday, 11/30, through Wednesday, 12/03, there were no changes in spacecraft configuration.

On Thursday, 12/04, Cassini Plasma Spectrometer (CAPS) cover release and data playback took place successfully.

Also on Thursday, a table in the Attitude and Articulation Control Subsystem (AACS) flight software was updated to enable inclusion of telemetry from the backup AACS Flight Computer (AFC) when the data rate from the spacecraft drops from the present 948 bps to 40bps. This data rate reduction will occur in mid-January 1998.

Upcoming spacecraft events:

Events for the week of 12/05 through 12/11 include: continuation of the MIMI decontamination activity, Solid State Recorder (SSR) maintenance (12/5), update of RPWS Flight Software (12/10), and 2 resets of the SSR pointers (12/05 and 12/11).

DSN Coverage:

Being past the L+30 point in its mission, Cassini no longer requires continuous DSN coverage. Over the past week Cassini had 1 DSN track period. In the coming week, there will be 4 DSN passes - on Friday, 12/05, Sunday 12/07, Wednesday, 12/10, and Thursday, 12/11.

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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