Cassini Significant Event Report

For Week Ending 07/21/00

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Wednesday, 07/19. The Cassini spacecraft is in an
excellent state of health and is operating normally. The speed of the spacecraft can be viewed on the "Where is Cassini Now?" web page.

Activities completed in the current C21 sequence include resetting of
the AACS Fault Protection Log pointer, a Reaction Wheel momentun unload,
clearing of the High Water Marks, the continuation of the Magnetospheric
Imaging Instrument (MIMI) functional test, Radio and Plasma Wave Science
(RPWS) checkout of Instrument Extended Blocks (IEB) to be used at Jupiter
and Periodic Instrument Maintenance (PIM), the Magnetometer Subsystem (MAG)
Boom Alignment Test, a Radio Science (RSS) UltraStable Oscillator (USO)
Calibration / Characterization, and RSS HGA Boresight Calibration. The USO
Cal was four hours in length and provides the Radio Science Operations
Team with information on the health and status of the on-board USO.
Because the character (i.e., the output frequency) of the USO will change
over time, this data is crucial to both the Operations and Science Teams.

The Imaging Science Subsystem / Visual and Infrared Mapping Spectrometer
(ISS/VIMS) ground system Level 5 Preliminary Design review was held. No
significant issues or concerns were identified.

Very preliminary analyses of the recently returned C20 science data
allowed the RADAR Operations Team to generate a new IEB, of about 11.5
hours duration. The block was successfully run through the RADAR
testbed. This IEB will be used in the C22 sequence activity on September

The Instrument Operations Team presented an E-kernel capability tutorial
at the Cassini Design Team Meeting. The E-kernel, which is part of the
Navigation Ancillary Information Facility (NAIF) suite of Spacecraft,
Planet, Instrument, C-matrix (pointing), and Events (SPICE) kernels will
provide an archive of Cassini ancillary data, including science plan,
sequences, and experimenter's notebook.

The Spacecraft Office successfully completed the end to end test of the
command files for the Command and Data System Flight Software upload and
checkout. The tests were run in system mode in the Integration and Test
Lab. The tests completed nominally and all command files were validated.
This is the final run through of the command files prior to uplink
beginning on July 29.

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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