Cassini Significant Event Report

For Week Ending 09/22/00

The most recent spacecraft telemetry was acquired from the Goldstone
tracking station on Wednesday, 9/20. 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.

Extensive activities were performed this week beginning with the uplink of
the Imaging Science Subsystem (ISS) Narrow Angle Camera / Wide Angle
Camera (NAC/WAC) power on and Flight Software (FSW) Load sequence. Both
the NAC and WAC successfully loaded their Instrument Expanded Blocks (IEB)
and placed themselves in sleep mode, awaiting Fomalhaut activities later
this week. Cassini Plasma Spectrometer (CAPS), Cosmic Dust Analyzer (CDA),
and Ultraviolet Imaging Spectrometer (UVIS) FSW loads were also successfully
completed with UVIS configured for Magnetospheric and Plasma Science
(MAPS) data collection.

On Sunday the spacecraft maneuvered to point at the star Fomalhaut for
Visual and Infrared Mapping Spectrometer (VIMS)/ISS/UVIS observations.
The spacecraft completed this activity nominally and the data from these
three instruments are being analyzed. ISS received all 30 images of
Fomalhaut, (21 NAC and 9 WAC). The NAC and WAC are operating nominally and
show the star positioned near the center of the field-of-view (FOV).
VIMS images of Fomalhaut showed the star seen in both the Infrared (IR)
and Visible channels near the center of the FOV.

The final instrument activity for this week was the ejection of the
Composite Infrared Spectrometer (CIRS) telescope cover. This activity
completed successfully and was followed with a twelve-hour mini-sequence
to generate science data and test the instrument. CIRS personnel report
that "Everything looks good so far".

Last week it was reported that real time commands were sent to the
spacecraft to optimize dust stream measurements made by CDA. This
enhanced their ability to observe a dust storm first detected in early
September. During the storm more than 250 impacts were recorded on one
day. Many of the signals are high quality allowing determination of the
chemical composition of the dust particles. The origin of the particles is
suspected to be Jupiter although it was not in the direct field-of-view of
the instrument. Submicron particles with speeds on the order of 100 km/s
(62.2 mi/s) originating from the Io-Jupiter system follow bent trajectories
by coupling to the Jovian and interplanetary magnetic field. This is the
first time that Cassini has observed a dust storm on approach to the
Jovian system.

Science Planning published an updated plan to the Project Science Group
(PSG) on the proposed next steps in the development of the Tour Science
Operations Plan (SOP). This plan outlines at a high-level the steps and
PSG support required to create the SOP prior to Saturn Orbit Insertion

RADAR completed Pointing Design Tool (PDT) designs for the C25 sequence.
For this sequence the instrument will acquire data while the High Gain
Antenna (HGA) is targeted at eight different targets. This will provide
the RADAR team with a considerable amount of data that is required to
calibrate the instrument in preparation for Tour planning.

RSS personnel began formal training on the new Radio Science Receiver
(RSR). Three members of the IO-RSS ops team will receive in-depth training
from the Deep Space Network (DSN) over the next several months.

The Emergency Control Center (ECC) in Goldstone, California was tested for
operations readiness this week. The purpose was to confirm software and
hardware configurations prior to Jupiter flyby activities. It was
determined that a few changes were desirable. After reconfiguration a
second evaluation will be scheduled.

Outreach held the first of two training sessions for Solar System
Ambassadors on the Jupiter flyby. Via teleconference and materials
available on the WEB, participating ambassadors conversed with project
members from Cassini, Galileo, and the Goldstone Antelope Valley Radio
Telescope projects. A web chat site for ambassadors preferring that
training method is scheduled to be utilized next week.

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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