Cassini Significant Event Report

For Week Ending 08/20/04

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, August 18. 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 .

On board activities included uplink and execution of a Cosmic Dust Analyzer (CDA) flight software checkout mini-sequence, memory readouts of the Command & Data Subsystem action log and non-interfering error log, and uplink of files to unmask the helium latch valve driver assembly fault protection monitors and to update the default main engine thrust value from 450 Newtons to 443 Newtons prior to Orbit Trim Maneuver(OTM) #2, aka the Periapsis Raise Maneuver (PRM).

Additional files were generated for use in Spacecraft Operations Office (SCO) testing of a representative PRM in the Integrated Test Laboratory (ITL). The final PRM will be approved August 19 for uplink and execution Monday morning August 23. This is the third largest maneuver to be performed during the mission, and the last planned fully pressurized maneuver in the remaining tour. The PRM is necessary to move the spacecraft path well outside the rings at periapsis, about 300,000 km farther away from Saturn than it was at Saturn Orbit Insertion.

Two previously unknown moons were discovered orbiting Saturn between Mimas and Enceladus. The moons are approximately 3 and 4 km across and are provisionally named S/2004 S1 and S/2004 S2. More information regarding these moons may be found on the Cassini web site.

Products were delivered for official port 1 as part of Science Operations Plan (SOP) implementation of tour sequences S35 and S36. Kickoff of SOP Implementation for S37/S38 begins next week.

The aftermarket process for sequence S07 completed this week, and requested changes were delivered and decision meetings held for both S08 and S09.

A preliminary port delivery was made for sequence S06 as part of the SOP Update process.

Three sequence change requests (SCR) were approved at an SCR approval meeting this week as part of the S04 Science and Sequence Update Process (SSUP). The SSUP is the final process in the development chain prior to the uplink of the background sequence to the spacecraft. The SCRs included a pointing change for Imaging Science Subsystem (ISS), sponge bit allocations, and two ISS memory readouts (MRO). In addition, the Preliminary Sequence Integration and Validation-2 stripped sub-sequences for S04 have been placed in the program file repository.

A waiver request disposition meeting and an SCR approval meeting were also held as part of the development process for S05. Five of the six SCRs were approved. These included a tweak to pointing to catch newly discovered cumulous clouds near Titan's south pole, a change of primary pointing of four satellite orbit determination observations to catch newly discovered moons, a pointing correction for a Titan A RADAR observation, addition of some Ion and Neutral Mass Spectrometer (INMS) resets, and two ISS MROs.

INMS, the Cassini Plasma Spectrometer (CAPS), and ISS have submitted sample archive data products and supporting documentation for review by the Planetary Data System Discipline nodes. INMS is including higher-level products in their archive.

The Planetary Data System and the RADAR team are conducting peer reviews of archive data Software Interface Specifications since data products are not yet available. The review includes raw and higher level products.

The subject of this week's tour plan presentation to the flight team was the Cross Discipline Target Working team's plans for tour.

A VIMS science team meeting was held this week in Denver, Colorado. Presentations were given on anomaly investigations, status of calibration and decontamination issues, and the proposed changes to the solid-state recorder library region.

A delivery coordination meeting (DCM) was held August 18 to review SCO Propulsion Tools version 3.1 and coordinate installation. The only changes in this delivery are in the Bipropellant System Performance Tool (BSPT) and the Monopropellant System Performance Tool (MSPT) files to allow outputs to be published to the program file repository.

A DCM was also held for the Mission Sequence Subsystem delivery of Cassini Information Management System version 3.2. The software was installed for operations use the same day. A tutorial and demonstration are tentatively planned for the instrument teams at an upcoming Science Planning Tour Process meeting in early September.

Cassini Outreach conducted two NASA workshops at the Girl Scout USA Headquarters - Edith Macy Conference Center, Briarcliff Manor, NY. Several "Saturn in your Kitchen and Backyard" activities were demonstrated for the leaders. Fifty Girl Scout, 4-H trainers, museum program managers and solar system ambassadors are now armed with a suite of solar system exploration activities which they will be incorporating into their programs. Cassini activities were demonstrated and copies of the activities were distributed to all. These activities can also be found on the Cassini Education pages .

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

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