Cassini Significant Event Report

For Week Ending 03/21/03

The most recent spacecraft telemetry was acquired from the Canberra tracking station on Wednesday, March 20. 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.

Attitude Control Subsystem (ACS) Flight Software checkout continued this week with the following activities performed: restoration of the custom telemetry schedule to the nominal schedule, live Inertial Vector Propagation update demonstration, demonstration of Star ID suspend, turns while in Reaction Wheel Assembly (RWA) control, reloading of the ACS Backup Flight Computer with the new version A8 flight software, setting of Backup Trickle, RWA friction test, and several high water mark clears and fault protection log pointer resets.

The Attitude Control Flight Software checkout has now very successfully concluded. The spacecraft hardware and new flight software have performed all checkout activities normally. Initial analysis shows that all objectives of the tests were met and the software will be able to meet all requirements for orbital operations. The Command and Data Subsystem (CDS) Flight Software checkout will begin a similar five-week checkout period on Monday. Two real-time command files will be uplinked for CDS to establish and verify the initial conditions prior to their CDS Flight Software checkout period.

Preliminary Sequence Integration and Validation products for C37 have been released. A simulation coordination meeting will be held next week. The first three days of the sequence will be tested to ensure that the background sequence and the Trajectory Correction Maneuver block are well integrated.

A NASA Independent Review Team (IRT) met with members of Cassini teams and offices this week. A draft report from the team contains positive findings with members of the board remarking on the progress of various teams since last year's IRT meeting. Also mentioned was the quality of the technical program, technical understanding, sound operations and development processes, and demonstrated problem solving ability of a very dedicated team.

The use of dual solid-state recorders (SSR) in the remaining portion of cruise was discussed at the Mission Planning Forum. It was agreed that dual SSRs would be used for CDS flight software checkout, Trajectory Correction Maneuvers 19, 19a, 19b, and the Saturn Orbit Insertion demo. Permanent dual SSR use will begin with C43 in February of 2004.

System Engineering hosted an Uplink Verification and Validation (V&V) readiness/kick-off meeting. Uplink V&V, beginning 3/31, is an end-to-end dry run of the tour uplink process to develop the final tour sequences sent to the spacecraft. Status items presented included team and tool status, test file deliveries and repositories, schedules, test trace matrices, success criteria, work remaining, and team readiness to go for the uplink V&V.

Mission Assurance presented a paper entitled "Cassini Risk Management during Mission Operations and Data Analysis (MO&DA) - Application and Lessons Learned" at last week's IEEE Aerospace Conference. The talk illustrated how Cassini implemented risk management during MO&DA, some of the challenges that were encountered, and how lessons learned led to improvements. The paper was well received by the audience and there was good discussion among session participants.

A Cassini image of Jupiter's Great Dark Spot was Astronomy Picture of the Day on March 19th. The image selected may be viewed at

Outreach assisted with check-in of projects and Q&A for a science fair at Barnhart School in Arcadia, California. In the evening, telescopes supplied by Outreach and the Los Angeles Astronomical Society allowed students to view Jupiter, Saturn, M42, and a host of other early evening objects.

Cassini project members participated in an outreach activity with the Aerospace Engineering department at California Polytechnic University (Cal Poly) in Pomona. They were invited to be part of a review board for student engineering projects with other representatives of the local aerospace industry. Fourth year students prepared material in response to a "request for proposal" for an asteroid reconnaissance mission. This review was the "preliminary design review" of their initial design solutions. The students will present their final designs at a "critical design review" in a couple months.

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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