Cassini Significant Event Report

For Week Ending 09/28/01

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

Recent instrument activities include an Interplanetary Hydrogen Survey by
the Ultraviolet Imaging Spectrograph, two Radio and Plasma Wave Science
High Frequency Receiver calibrations, a Visual and Infrared Mapping
Spectrometer timing test, and a Radio Science Subsystem (RSS) dataflow
test. Engineering activities taking place onboard the spacecraft this week
include an Attitude Control Subsystem (ACS) deadband test, which will
provide data for a trade study on hydrazine consumption under two Reaction
Control Subsystem deadband settings. A real-time command was uplinked to
the spacecraft to clear the ACS high-water marks.

The eighth Huygens in-flight check-out (F8) was successfully executed this
week. Onboard the spacecraft, the Probe Support Avionics were turned on
and operated for several hours. The telemetry data was downlinked in real
time from Cassini to the Goldstone tracking station and broadcast to the
Huygens Probe Operations Center in Darmstadt, Germany, via the JPL/Cassini
ground system. An initial assessment of the telemetry indicates that all
sub-systems and payloads performed as expected, and the science data have
already been distributed to all Huygens science teams, with preliminary
reports from each team expected within the next week. The F8 Operations
Report will be ready for the F8 Check-out Review, which will take place at
European Space Research & Technology Centre (ESTEC) on December 5 & 6.

The RSS team conducted the first of two data flow tests this week. The
objective was to further RSS Verification and Validation efforts in
preparation for the Gravitational Wave Experiment (GWE). The RSS team also
uplinked a Ka-band signal to the Ka-band Translator (KaT) to continue
development of a final KaT operational strategy for the GWE.

The Sub-Sequence Generation (SSG) phase of the C29 sequence process has
been completed and the Preliminary Sequence Integration & Validation
(PSIV) phase has begun.

The Command and Data Subsystem (CDS) Flight Software (FSW) team delivered
the fourth iteration of the CDS FSW v9.0 as part of the continuing
development of that FSW package.

System Engineering (SE) worked with the Uplink Operations team to schedule
the Mission Sequence Subsystem (MSS) D8.0 delivery. This delivery must
accommodate the new command database (ACS and CDS FSW changes) and the
change to the new Sun Operating System, in addition to supporting the
normal cruise sequences. The plan was presented to Program Management for

Mission Assurance has updated the Program Review Plan & Schedule. This
plan outlines the Programmatic Reviews that are scheduled to take place
for the remainder of the mission, particularly those addressing readiness
for Saturn Orbit Insertion and Probe Relay operations.

A paper entitled Managing Risk for Cassini During Mission Operations and
Data Analysis has been written by Mission Assurance and submitted for the
2002 IEEE Aerospace Conference. This paper describes the Risk Management
Process that Cassini has put in place to manage operational risks, and
includes preliminary metrics and outlines what metrics will be kept to
ensure that the process is effectively managing risks. The paper is
scheduled to be presented at the conference in March 2002.

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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