Cassini Significant Event Report

For Week Ending 04/25/03

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, April 23. The Cassini spacecraft is in an excellent state of health and is operating normally. Information on the spacecraft's position and speed can be viewed on the "Present Position" web page.

The Command and Data Subsystem (CDS) Flight Software (FSW) checkout activities continued this week with Instrument Expanded Block (IEB) exercises for the Ultraviolet Imaging Spectrograph (UVIS), Imaging Science Subsystem (ISS), Visual and Infrared Mapping Spectrometer (VIMS), and Cosmic Dust Analyzer (CDA). Also performed were a CDS Version 9 telemetry mode checkout and a demonstration of the ability to enable and disable critical controllers via sequenced commands. Real time commands were sent to the spacecraft to turn off the UVIS high voltage power supplies, clear Attitude Control high water marks, and clear the CDS error logs. The checkout activities will complete this week with an optical navigation test.

A Preliminary Sequence Integration and Validation (PSIV) approval meeting was held for cruise sequence C37. The sequence was approved for uplink at that time so a final (SIV) meeting will not be necessary. The sequence will be uplinked at the end of this week and will begin execution on April 29.

A project briefing was held for cruise sequence C38. C38 is designed to be a minimal activity sequence in order to accommodate concurrent ground system verification and validation activities. In addition to activities to be executed during the sequence such as the Saturn orbit insertion demonstration, options were discussed for the Solar Conjunction Experiment and the 30 days of continuous DSN coverage that has been requested for this activity.

The Navigation Software Development team delivered a complete engineering set of the Linux based navigation software. In the areas tested so far, significant performance improvement has been observed.

The Mission Sequencing Software team obtained project approval for their development plan for the version 9.1 delivery scheduled for mid-July. This delivery will support science planning and sequencing through spring of 2004.

The Composite Infrared Spectrometer (CIRS) team has delivered version 2.0.1 instrument flight software to the Project Software Library.

Additional information about Cassini-Huygens is online at

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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