Cassini Significant Event Report

For Week Ending 09/21/01

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Wednesday, September 19. 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.

Recent instrument activities include the conclusion of a detailed solar
wind study by the Cassini Plasma Spectrometer, two Radio and Plasma Wave
Science High Frequency Receiver calibrations, a Cosmic Dust Analyzer (CDA)
decontamination activity, and the first part of a CDA noise evaluation
study. Engineering activities taking place onboard the spacecraft this
week include a calibration of the Stellar Reference Unit and a periodic
engineering maintenance activity that exercised both the Engine Gimbal
Actuator and backup Reaction Wheel Assembly. Real-time commands were
uplinked to the spacecraft to clear the Attitude Control Subsystem (ACS)
high-water marks.

A Command Approval Meeting was held to seek approval for uplink of the
Visual and Infrared Mapping Spectrometer (VIMS) Flight Software (FSW)
version 4.2 to the Solid State Recorder and to load it into the
instrument. The FSW was successfully uplinked and loaded on September 20.

The C29 Sequence Team process began this week with delivery of the first
stripped subsequence Spacecraft Activity Sequence Files (SASFs) and
integrated sequence files. The kickoff meeting was held, and each team is
currently in the process of completing and reviewing their detailed
subsequence SASFs. C29 will feature the first use of "cyclics", which use
a call from the background sequence to run an external program multiple
times, conserving sequence space by not having to expand the program for
each occurrence. This capability will be essential for the tour.

The C30 Science Planning Team development process began this week and is
preparing for the Program briefing next week.

An all-day Titan Orbiter Science Team (TOST) meeting was held this week.
The TOST started integrating the plans for Titan encounters T11 through
T22 outside of the +/- 30-minute period around Titan closest approach.
The period within +/-30 minutes for all the remaining Titan flybys was
also worked.

The Imaging Science Subsystem (ISS) team completed the initial
implementation of ISS FSW upgrades. The first basic tests have begun on
Electronic Ground Support Equipment, and a full Acceptance Test Plan is
being prepared.

Developers for the Mission Sequence Subsystem (MSS) ground software
package have drafted a final plan for basic MSS D8.0 infrastructure,
including support for the UNIX Sun Solaris 2.7 operating system and a new
command database that includes Command & Data Subsystem version 9 and ACS
version 8 FSW.

Outreach is taking delivery of its new educational poster, "Cassini
Unveils the Myth" this week. The front of the poster features a mural
painted by middle school artists showing Kronos unveiling Saturn, while
the back provides classroom lessons for teachers. The poster will be
available by request to the Cassini Program and from the nationwide
Educator Resource Center Network and NASA CORE.

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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