Cassini Significant Event Report

For Week Ending 03/29/02

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, March 27. 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.


On board activities this week included a Radio and Plasma Wave Science (RPWS) High Frequency Receiver calibration, the normalization of Visual and Infrared Mapping Spectrometer (VIMS) flight software, clearing of the Attitude Control Subsystem (ACS) High Water Marks and an autonomous CDS Solid State Recorder memory load partition repair.


The Preliminary Sequence Integration & Validation (PSIV) phase has begun for C32. Inputs have been received from all participating instrument teams and the Spacecraft Office, and the merged products have been released for review.


VIMS analysis of in-flight flight software tests uncovered a software error. The new capability of inserting the observation time into the spectral data for return in telemetry is affected. The symptom is that the spectral data becomes shifted from its proper location. Ground testing did not detect the flaw because there is no Engineering Model capable of simulating this aspect of the instrument. An Incident Surprise Anomaly report will be written to document the error and testing of the flight software will continue.


Final preparations were completed this week for next week's uplink of Trajectory Correction Maneuver (TCM) 18. The Maneuver Automation Software set has been tested and delivered for operations, the Integrated Test Laboratory (ITL) successfully tested the TCM-18 maneuver block, and the SCO has completed simulation of the health and safety check and go for the uplink process.


The TCM-18 maneuver is using many of the processes, software, and personnel teams that are being developed for use during the Saturn tour. The maneuver was produced using the new Maneuver Automation Software (MAS) tool. This tool greatly reduces the time and personnel required to generate and verify a maneuver. Maneuver execution will begin and end Earth-pointed. Roll turns will be performed under reaction wheel control, while yaw turns will be performed with the reaction control system. Science data playbacks and real-time Magnetospheric and Plasma Science (MAPS) data collection will be performed before and after the maneuver.


Cosmic Dust Analyzer personnel delivered an update to their instrument flight software to the program software library. A delivery coordination meeting will be held next week.


The System Engineering Office hosted a meeting this week to discuss Solid State Recorder Carryover interaction with the Ground Data System, held a delivery coordination meeting for the Navigation Ancillary Information Facility (NAIF) toolkit, and supported a working group focusing in on design and trades for proposed Science and Sequence Uplink Process system-level Verification and Validation (V&V) activities. The Mission Sequence Subsystem (MSS) version D8 Modules were tested in the ITL. A total of 16 modules and approximately 80 test cases were run, with only one test case failure, and that one attributable to input values for the case. A revised test case has been submitted for retest in ITL.


All except one MSS application has entered code hard freeze. The exception is the Pointing Design Tool, which has taken longer to finish unit testing than anticipated. PDT is scheduled to enter hard freeze next week.



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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