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Significant Event Report for Week Ending 7/31/1998

Cassini Significant Event Report

For Week Ending 07/31/98

Spacecraft Status:

The most recent Spacecraft status is from the DSN tracking pass on Saturday, 07/25, over Madrid. The
Cassini spacecraft is in an excellent state of health and is executing the C9 sequence nominally. 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)

Inertial attitude control is being maintained using the spacecraft's hydrazine thrusters (RCS system). The
spacecraft continues to fly in a High Gain Antenna-to-Sun attitude. The downlink telemetry rate is presently
40 bps.

Spacecraft Activity Summary:

Telemetry from the DSN track on Friday, 7/24, confirmed that the quarterly Periodic Instrument Maintenance
(PIM) activity, performed on 7/23 and 7/24, completed as planned.

Also on Friday, an SSR Flight Software Partition maintenance activity was performed. This activity, scheduled
approximately every 2 weeks, repairs any SSR double bit errors (DBEs) which have occurred in the
code-containing portions of the Flight Software partitions during the preceding period.

On Wednesday, 07/29, the Solid State Recorder (SSR) record and playback pointers were reset. This
housekeeping activity, performed 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.

Upcoming events:

Activities scheduled for the week of 07/31 - 08/06 include: power off bus heaters (7/31), update address
range for AACS trickle MRO data (7/31), store RTE158-enable and ATC6 parameter-update software on
SSR (8/1), perform SSR FSW Partition Maintenance and SSR Pointer Reset (8/05), and perform an Attitude
Estimator MRO (8/06).

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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