Significant Event Report for Week Ending 12/20/2002

Cassini Significant Event Report

For Week Ending 12/20/02

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, December 18. 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 Radio and Plasma Wave (RPWS) High Frequency Receiver calibrations, an ACS High Water Mark clear, and uplink of the RPWS looper program #2. The program will begin execution at the beginning of next week.

Gravitational Wave Experiment #2 continues. Operations were normal from Day of Year 343 through 347. Beginning DOY 348, the DSS-25 X-band transmitter has been tripping off, resulting in loss of 2-way X-band and Ka-band links. Mission Support and Services Office personnel are working with the Deep Space Network to possibly add DSS-24 or DSS-26 in parallel to the DSS-25 tracks to maintain the X-band uplink. Radio Science continues to provide round-the-clock staffing for the GWE.

Processing of the data returned from Probe Relay test #5 is now complete. Analysis continues.

The Command and Data System (CDS) Flight Software Team held a successful Software Requirements and Certification Review for a five bit per second telemetry mode patch to the CDS software. The patch is necessary to properly configure the Version 7 CDS flight software prior to uplink of the Version 9 CDS flight software which will begin in March, 2003. The patch was delivered to the Project Software Library and will be uplinked to the spacecraft in January, 2003. The end-to-end test of the procedures for the Attitude Control System (ACS) FSW uplink and checkout continues to run smoothly and is nearly complete. This is a major system mode test of the all ACS activities during the FSW checkout period beginning in mid-February. The Integrated Test Lab has been running continuously in system mode for over nine days.

The Navigation team has documented the baseline maneuver strategy and timeline for the Huygens mission. This
timeline was recently approved by Cassini and Huygens at the Quarterly Progress Meeting held at JPL on Dec.4-5.

The topic at this week's Mission Planning Forum centered on pointing changes based on ephemeris updates during the tour. Navigation discussed some software that has been developed to assess the pointing changes in going from previous to new geometries.

All teams and offices presented at the December Cassini Monthly Management Review.

The Cassini Navigation and Ancillary Information Facility staff met with the Huygens Descent Trajectory Working Group to discuss how Spacecraft, Planet, Instrument, C-matrix, and Events kernels will be deployed in support of Huygens descent operations.

It was reported in NASA Science News for December 13, 2002 that on December 17, Earth and Saturn had their closest encounter in nearly 30 years. Furthermore, the planet's rings are tipped toward Earth. It is an unbeatable combination for sky watchers who can easily see Saturn's rings using backyard telescopes or binoculars. For the full story connect to https://science.nasa.gov/science-news/science-at-nasa/2002/13dec_saturn

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 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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