Cassini Significant Event Report

For Week Ending 05/17/02

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Tuesday, May 14. 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.

Instrument activities this week included Visual and Infrared Mapping Spectrometer (VIMS) and Imaging Science Subsystem (ISS) observations of Spica, Ultraviolet Imaging Spectrograph (UVIS) observations of the Io torus, a UVIS Hydrogen Deuterium Absorption Cell conditioning activity, an ISS Narrow Angle Camera decontamination activity, a Composite Infrared Spectrometer boresight calibration, uplink and execution of Cosmic Dust Analyzer (CDA) Flight Software (FSW) and FSW checkout mini-sequence, a CDA decontamination activity, and uplink of Radio and Plasma Wave Science (RPWS) Instrument Expanded Block and FSW patches.

ISS performed diagnostic imaging of Spica. Initial analysis indicates a marked increase in image quality after more than 60 days of instrument temperatures held above 4C, although contamination still appears to be present at low levels. The next cycle of warm-up and imaging has already begun, and will indicate if improvement is tapering off. The CDA FSW load procedure was successfully completed with all files being received and expected memory readouts returned. The ACE confirmed CDA mini-sequence registration and activation on board. The CDA FSW checkout ran nominally with the exception of a ion grid voltage reset. This is a minor anomaly and may be reset later without impact. Finally, RPWS reported seeing the Immediate/Delayed Action Programs execute as expected.

After the conclusion of instrument activities, a Reaction Wheel Assembly unload was performed. Reaction wheels were then powered off and the spacecraft returned to Reaction Control Subsystem control. Additional on-board activities included clearing of the AACS high water marks and an autonomous CDS Solid State Recorder memory load partition repair.

Science Planning completed development of the C33 sequence, and provided a handoff package to the Sequence Team. A Sequence Generation kickoff meeting was held for C33, stripped subsequences were released to all instrument teams and the Spacecraft office, and an integrated Sequence of Events file and Space Flight Operations Schedule were released.

After the conclusion of the orbital Sequence Uplink Verification activity, a meeting was held to review "lessons learned" from the exercise.

Science Operations Plan implementation activity kicked off this week with initial development of the S09 and S10 sequences for orbits 4 through 10.

In support of Science Operations Plan implementation, Mission Sequence Subsystem (MSS) software version D8 was installed on all Solaris 7 Science Operations and Planning Computers and Operations workstations. Mission Support and Services Office personnel were able to accomplish the installation ahead of schedule and thus ensure availability for this new high priority science planning activity.

Final development and start of system testing for MSS D8.0.1 is underway. The D8.0.1 versions of the Kinematic Prediction Tool and Inertial Vector Propagator Tool will be delivered this week for inclusion in D8.0.1 Pointing Design Tool.

A partial walk-through of the SSR Management Tool (SMT) code was held with personnel from Mission Planning, and Spacecraft Office Command & Data Subsystem. A few changes were identified. If time permits, minor updates may be made to the 8.0.1 release of SMT. If not, the suggested changes will be incorporated in a later delivery.

Based on a proposal from the Southwest Research Institute (SwRI), and the results of a technical evaluation, a requisition for additional funding for SwRI to continue the current level of effort through FY02 has been sent to the JPL contracts office. This will cover the remainder of the work on Cassini Information Management System that Cassini requested this fiscal year.

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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