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Significant Event Report for Week Ending 3/8/2002

Cassini Significant Event Report

For Week Ending 03/08/02

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, March 6. 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 include two Radio and Plasma Wave Science High Frequency Receiver calibrations and a Visual and Infrared Mapping Spectrometer (VIMS) timing test. Initial indications showed that all commands from the VIMS Instrument Expanded Block (IEB) mini-sequence for this test were executed with good response.

A series of real-time commands was uplinked to the spacecraft this week to clear the Attitude Control Subsystem (ACS) high-water marks, perform a Command & Data Subsystem (CDS) Memory Readout of sequence statistics, clear the CDS online string reset counter, power on the Imaging Science Subsystem (ISS) decontamination heater, and change the Command Detector Unit (CDU) rate to change the uplink bit rate from 250 bps to 500 bps.

A highly successful Critical Design Review (CDR) of the Uplink Mission Operations System for the tour phase was held on February 27 and 28. Areas reviewed included science planning updates, sequence generation, pointing ops, real time commanding, SSR management, optical navigation, maneuver design and
support imaging. This is the third of four CDRs to be held for tour operations.

A successful demonstration for Cassini use of the new command system, CMD v26.3.1, was conducted this past Tuesday using the Goldstone Deep Space Communication Center (DSCC). This test was the culmination of a series of acceptance tests for the new system. Four commands were radiated from the Goldstone DSCC, and were verified as having been received and executed aboard the spacecraft. Two more demonstrations are planned, one each for the Canberra and Madrid DSCCs.

The C31 Preliminary Sequence Integration and Validation (PSIV) approval meeting was held and the sequence approved for uplink. The sequence will be radiated to the spacecraft Thursday March 7, and will begin execution Sunday March 10. The command approval meeting held to prepare for the sequence uplink also approved the uplink of a second VIMS IEB replacement mini-sequence.

Cassini participated in a test of new DSN firmware late this week. The spacecraft was commanded to transition to the 35Kbps telemetry mode and downlink data so that DSS-25 could exercise the new firmware. All initial Cassini indications showed the test proceeding smoothly.

A detailed Planetary Data System (PDS) data archiving schedule has been created and sent out for review by the Cassini instrument teams. PDS imaging personnel will be traveling to Tucson in the next month to meet with VIMS team members and work the details of developing the PDS archive for their instrument.

Cassini Jupiter magnetosphere science was included in an article in the Los Angeles Times this week, viewable online at http://www.latimes.com.

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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