Cassini Significant Event Report

For Week Ending 03/05/04

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, March 3. The Cassini spacecraft is in an excellent state of health and is operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the "Present Position" web page located at .

C43 activities continued this week with a Composite InfraRed Spectrometer mirror calibration, RADAR Instrument Expanded Block (IEB) exercise, Optical Navigation SSR IEB load, Cassini Plasma Spectrometer power on/off and high voltage IEB trigger Immediate/Delayed Action Program uplink, Radio and Plasma Wave Science solar wind observation, Imaging Science Subsystem (ISS) Saturn Approach movie, and spacecraft periodic engineering maintenance.

The prime activity this week was execution of the Huygens Probe Relay Critical Sequence demonstration. Prior to the event, all instruments were either turned off or muted and placed in sleep. 24-hour coverage was provided for the four days of the demonstration by the Goldstone, Madrid, and Canberra DSN complexes. Personnel from the Spacecraft Operations Office, Mission Support and Services Office, Probe, and the Instrument Operations Distributed Operations Coordinator supported the exercise.

The activity began with uplink of sequences to the Solid State Recorder, and culminated in the delivery of probe data to the Huygens Project Operations Center in Darmstadt, Germany. The demonstration included the spacecraft turning to the Probe Relay attitude, recording approximately six hours of simulated Probe data, then turning back to Earth to downlink the Probe data at the expected mission rates to the 70 meter DSN station at Goldstone, California.

In the last week, 185 ISS images were acquired and distributed before the instrument went to sleep for the Probe demonstration. So far in Approach Science, 994 ISS images have been acquired. Of those, 84 are optical navigation images.

The C44 Preliminary Sequence Integration and Validation Sequence Change Request approval meeting was held this week.

Preliminary and official port 2 deliveries were made for Science Operations Plan (SOP) Implementation of tour sequences S23 and S24. A wrap-up/program briefing/waiver disposition meeting was held for SOP Update of S01, the first tour sequence. Sequence generation will begin next week.

Science Planning launched a series of Tour Science Plan presentations to the flight team with an historical overview of the timeline and process that led to selection of the current baseline tour, and how that tour would then be segmented and integrated with detailed science requests from which the tour sequences would be developed.

Members of Program Science and SCO met to discuss G ring brightness in the star tracker during the ascending ring plane crossing just prior to Saturn Orbit Insertion. Further dialogues will be held with some ring scientists to obtain information on G ring brightness, and some G ring scientific papers were identified for SCO to reference. Another topic discussed involved small satellites, 3.5 to 7 km diameter, that might be confused as stars. The Voyager upper limit for this region was 10 km. Hubble images can detect moonlets down to 3 km, but no Hubble searches in the vicinity of the G ring have been done.

SCO delivered ground software for Maneuver Automation Software (MAS) version 4.3. The MAS tool takes the Navigation solution for a trajectory correction maneuver and builds a sequence ready for uplink to the spacecraft in less than 30 minutes.

Additional Delivery Coordination meetings were held for the Navigation T1.1 and Mission Sequence Subsystem D10.2 software.

Outreach personnel participated in a career day at San Dimas High School in San Dimas, California. Eighty students attended a two-hour presentation and discussion.

The "Where is Cassini Now?" page of the Cassini website has been updated to reflect the spacecraft's pending arrival at Saturn. The new page can be viewed at:

The release of the latest Saturn image resulted in the largest traffic volume ever seen on the Cassini home page. The previous high was the Astronomy Picture of the day on Dec.10 with ~ 638,000 requests, 3.8 gigabytes of information transferred, ~ 14,000 unique visitors and 38,000 pages. The Feb. 27th release put that to shame with 1,813,319 requests, 12.71 gigabytes of information transferred, 21,153 unique visitors and 105,528 pages. Overall, traffic to the Cassini site has increased since the Mars rover landings, roughly quadrupling from previous months' averages. The website can be located at:

MSNBC recently reported on an update to a Cassini website for children. With the Cassini spacecraft sending regular postcards from Saturn and its surroundings, a scientific storyteller sent a timely reminder regarding NASA's Jet Propulsion Laboratory and the Cassini children's tale. The site can be located at:

An additional MSNBC report described Saturn and its rings taking center stage in the Cassini spacecraft's latest picture, snapped from 69.4 million kilometers away

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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