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 (SOI).

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 http://saturn.jpl.nasa.gov.

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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