Cassini Significant Event Report

For Week Ending 09/10/04

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, September 8. 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 .

Science activities this week included optical remote sensing (ORS) scans and movies of Saturn's south pole to observe waves and storms at southern latitudes, ultraviolet mosaics of Saturn's magnetosphere, and mosaics of the rings and Saturn's south pole. The Magnetospheric and plasma science (MAPS) instruments continue observations of the solar wind, and the Cassini Plasma Spectrometer (CAPS) performed a solar wind beam calibration.

Additional on-board activities included the successful uplink and execution of an Ion and Neutral Mass Spectrometer flight software (FSW) checkout mini-sequence, uplink and execution of a file for CAPS that will run for five days containing time-of-flight setting changes for solar wind calibrations, Orbital Trim Maneuver-3 (OTM), and uplink of an Imaging Science Subsystem (ISS) FSW patch. The memory patch will alter the response to a 'machine error' to be such that operations are not halted. The patch was tested on the ISS test bed and in the Integrated Test Laboratory (ITL). Unless a power cycle occurs, no further action is needed until a new version of the FSW is ready next year.

OTM-3, the periapsis raise cleanup maneuver, was successfully completed on the spacecraft on September 7. A "quick look" immediately after the maneuver showed the burn duration was 3.6 sec, giving a delta-V of 0.49 meters per second. This was the shortest duration main engine maneuver performed to date.

As with OTM-2, a special ranging procedure was used during this maneuver. The transmitter was left on and ranging disabled until the spacecraft came back to Earth-point. A Magellan acquisition (MAQ) was performed while the transmitter was still on. This was done in order to obtain range points after the maneuver as well as before.

ACS FSW version 8.7.1 end-to-end testing in the ITL was completed this week. The test exercised the uplink and checkout of the Probe and Tour mission flight software that will execute onboard the spacecraft starting September 28.

The European Space Operations Center (ESOC) conducted a Huygens Probe Operations Center (HPOC) Readiness Review on September 2. HPOC is located at the ESOC facility in Darmstadt, Germany. The review board was composed of members of the Cassini-Huygens Project and ESOC and European Space Agency personnel. The board was unanimous in its conclusions that HPOC was well prepared to support the Huygens mission and that preparations for the science teams were appropriate.

Preliminary and Official port 2 deliveries were made this week for the Science Operations Plan (SOP) Implementation process for tour sequences S35/S36. The team files were merged and a report was delivered identifying any issues or problems. A waiver approval meeting was also held in support of this process.

The Project Briefing and Waiver Disposition meeting was held as part of the SOP Update process for S06. This process completed on Friday, September 3 with a handoff package delivered to the Uplink Operations Team.

The Aftermarket processes for S08 and S09 completed this week. SOP Update will begin on September 20 for S08, and on September 23 for S09.

A presentation was given on Ultraviolet Imaging Spectrograph ring science results at the weekly Science Planning Tour Science Talk.

Development for S04 concluded this week with the publication of the final sequence products for review, Command Approval Meetings held for 16 Instrument Expanded Block (IEB) load files, the background sequence, and three additional files, and the uplink of 7 of the 16 IEB files. This sequence goes active on the spacecraft on Saturday.

A delivery coordination meeting was held for Spacecraft Operations Office ground software tools Kinematic Prediction Tool 10.3.6 and Inertial Vector Propagator 10.3.4.

Two new press releases have appeared on the Cassini Web Site. One gives the details of the discovery of one small body, possibly two, orbiting in the F ring region, and a ring of material associated with Saturn's moon Atlas. The other gives information on data taken by the Composite Infrared Spectrometer while entering Saturn's orbit showing the cool and relatively warm regions of the rings.

For the most recent Cassini information, press releases, and images, go to