Cassini Significant Event Report

For Week Ending 05/11/01

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Monday May 7. The Cassini spacecraft is in an
excellent state of health and is operating normally. (Subsequent to the
time period covered by this report, the Cassini spacecraft entered safing.
The cause is well understood, the spacecraft is in a completely safe
state, and recovery efforts are underway. Details will be included in next
week's report.) Information on the
spacecraft's position and speed can be viewed on the
"Present Position"
web page.

Recent spacecraft activities include characterization and power-off of
Solid State Recorder (SSR)-A. The characterization tests included a memory
test, data formatter test and module controller interface tests. Also
performed was a procedure to patch the Command & Data Subsystem (CDS)
Flight Software (FSW) in the SSR-B non-default partition with an update
for the Magnetometer Subsystem (MAG) replacement heater Solid State Power
Switch (SSPS) algorithm. The procedure included reloading CDS-B with the
newly patched FSW, and patching CDS-A FSW running in RAM with updates for
the MAG heater and the Low Gain Antenna (LGA). All activities executed

Additional spacecraft activities included the a Radio and Plasma Wave
Science (RPWS) High Frequency Receiver (HFR) calibration, a high water
mark clear, and uplink of an Instrument Expanded Block (IEB) and execution
of a sensor mode checkout minisequence for Cassini Plasma Spectrometer

The Radio Science (RSS) team concluded the Gravitational Wave Experiment
(GWE) system test #1 this week. About 40 hours of Ka-2 coherent data, 60
hours of Ka-1 coherent data, and over 100 hours of X-band data were
collected. Additionally, the team collected about 60 hours of media
calibration data that will be processed into path delay files for each of
the DSN tracks. The system test also provided further information for
characterization of the Ka-band Translator (KaT). The RSS team, with
assistance from the DSS-25 Upgrade Task, developed a new Ka-band
acquisition template crucial to this effort. The template was used for
all DSS-25 tracks.

Science planning tool user scenarios were presented at the Cassini Design
Team meeting by the Science Planning team, and ground software tool
classifications and related requirements were reviewed at the System
Engineering Round Table working group.

The Cassini Mission Plan has been reorganized by the Mission Planning Team
in support of a new delivery of the document at the end of May. A review
of the maneuver strategy and maneuver timeline of events was held in the
Mission Planning forum, and the updated Consumables Report was released.

Mission Assurance has updated the process by which anomalies are reported
for Cassini to more accurately reflect current operations. An updated
Anomaly Reporting Plan has been distributed for flight team review. The
new process will be presented to the Cassini Design Team for approval and
implementation. Mission Assurance has also begun tailoring a prototype,
web-based Risk Management Tool developed for Cassini, to be consistent
with the Program's risk management process. The tool is expected to be
released for use within the next month.

The Instrument Operations (IO) Team developed an Event Kernel (EK) web
query tool prototype and released it for evaluation by members of the EK
working group. This prototype will help the EK development team further
refine the requirements for EK data and an interface to that data.

The Cross-Discipline Workshop (CDW) report was published, which summarized
the results of the Tour segmentation done by the Tour Splinter Groups
formed during the workshop. The Atmospheres Working Group held a
teleconference to work on atmospheric occultation requirements.

A group of students operating the Goldstone-Apple Valley Radio Telescope
(GAVRT) in coordination with the Cassini RADAR team presented their
results to JPL and NASA staff this week. Attending the presentation were
RADAR Team Leader and JPL Director Charles Elachi and Cassini Program
Manager Bob Mitchell, with Administrator Dan Goldin, U.S. Rep. Jerry Lewis
(Redlands, CA) and GAVRT/Cassini Coordinator Scott Bolton attending via
telecast from NASA HQ. The GAVRT team observed the long-term and short-term
variability of Jupiter's synchrotron emission to provide a solid baseline
of Jupiter's radiation belts behavior at the time of the Cassini Jupiter flyby.
Working as science partners with the Cassini RADAR team, the GAVRT team's
observations will be used to calibrate the Cassini RADAR instrument. Their
observations confirmed the state of Jupiter's radiation belts at the time
of the experiment, and provided a unique contribution by observing before
and after the flyby.

Cassini presentations were made to the Young Astronauts program on May 2nd
and 3rd in Spokane, WA. The Young Astronauts webcasts are broadcast to
elementary school children across the U.S. Students phone in with
questions at the end of the program.

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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