Significant Event Report for Week Ending 3/28/2003

Cassini Significant Event Report

For Week Ending 03/28/03

The most recent spacecraft telemetry was acquired from the Canberra tracking station on Wednesday, March 26. 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 last activity of the Attitude Control Flight Software (FSW) checkout was a successful Reaction Wheel Assembly friction test. After that, real time command files were uplinked to set global variables for the string swap procedure, and memory readouts for the SSR flight software regions. These commands enabled Command and Data Subsystem (CDS) personnel to establish and verify initial conditions prior to their CDS FSW checkout period. The CDS checkout began with activities to load the new version 9 FSW onto the on-line "backup" CDS string, and a string swap procedure to reset the CDS_A string executing Version 7.0, and allow the CDS_B String with Version 9.0 to become the prime CDS string. The swap was successfully completed. The CDS_A string will continue to execute the Version 7.0 software as a "hot" backup until Thursday, when CDS_A will also be loaded with Version 9.0.

A delivery coordination meeting was held for Version 2.0 Release 1 of the Remote Terminal Interface Unit (RTIU) software. This delivery was needed to allow the Ion and Neutral Mass Spectrometer (INMS) instrument to replay bus traffic from their recent tests in the Integrated Test Laboratory (ITL) using their RTIU and engineering model in Michigan. Previously the RTIU had a limit of 1024 commands in a sequence. The INMS tests in ITL exceeded that limit so the number was increased to 2048. The RTIU software simulates the Cassini CDS, and provides the CDS functionality needed for testing instrument commands and data telemetry.

The Navigation Ancillary Information Facility toolkit, version N0055, with Cassini components tested, was delivered to the Project Software Library (PSL).

The Southwest Research Institute in Boulder, Colorado has made the ISS "pre-commanding" tool software available for download by IO personnel. User documentation is also included. This version of the software has been delivered to the development network side of the PSL. After testing by IO, the software will be officially delivered to the PSL.

Members of the Navigation team presented contingency missions and trajectories for the Huygens Probe at the Mission Planning Forum this week.

Students throughout Los Angeles and Orange Counties have gazed at Saturn through telescopes in the past two weeks. Members of the Saturn Observation Campaign have hosted a series of events throughout Southern California.

The Cassini Program Manager gave two lectures on the Cassini-Huygens Mission To Saturn, one in Von Karman Auditorium at JPL, and the other at The Vosloh Forum at Pasadena City College, California.

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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