25 Jan 2002
(Source: Jet Propulsion Laboratory)
Cassini Weekly Significant Events for 01/17/02 - 01/23/02
The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, January 23. The Cassini spacecraft is in an excellent state of health and is operating normally. To see where it is now, check the present position web page.
The C30 sequence continues to execute as planned. Science activities this week include the completion of a Composite Infrared Spectrometer (CIRS) functional test. This mini-sequence performed a functional checkout as the instrument transitioned from science mode, to sleep mode, and powered off. The Imaging Science Subsystem (ISS) decontamination mini-sequence began execution, with the Visual and Infrared Mapping Spectrometer riding along. The spacecraft was turned to Spica with ISS taking a number of images using the Narrow Angle Camera. The spacecraft then returned to Earth point with ISS decontamination heater #1 and the ISS replacement heater left in the ON state. Decontamination activities will continue through the end of the month when a second set of images will be obtained.
Spacecraft activities included transition from Reaction Control Subsystem to Reaction Wheel Assembly mode in support of the ISS mini-sequence, a Command & Data Subsystem (CDS) Solid State Power Switch trip counter reset, and an autonomous CDS Solid State Recorder memory load partition repair.
In support of a Deep Space Network (DSN) request to test a new version of their firmware, a DSN Block 5 Receiver firmware test Immediate/Delayed Action Program (IDAP) was uplinked. The IDAP will execute next week, putting Cassini into 82K downlink mode over DSS-15, and returning to S&ER3 near the end of the pass.
The 27th Cassini Project Science Group (PSG) meeting concluded during this reporting period. Titan Orbiter Science Team and Satellite Orbiter Science Team meetings were held to continue working integration issues for the Titan and icy satellite flybys. Also during PSG week the Cross-Discipline Workshop's Equatorial Splinter Group was reactivated to re-segment the tour prior to the Titan 3 (T3) flyby. The re-segmentation was required due to the new probe mission design. The group successfully segmented the tour for this time frame and allocated the segments to the appropriate Target Working Teams.
Mission Planning gathered science response and impacts to proposed trajectory tweaks for tour. The tweaks included moving ring plane crossings to reduce the probability of dust impacts to the spacecraft and instruments. A presentation on the findings will be made next week. Archiving status reported by Instrument Operations indicated that many of the instrument teams have made progress identifying their data sets and working with the Planetary Data System (PDS) to design archive volumes and data processing systems. The Huygens Probe PDS representatives have been identified, and work to develop the Huygens PDS archive has begun. Radio Science plans to archive reduced products including atmospheric T-p profiles, ionospheric electron density profiles, ring opacity profiles, GM and higher order results from various gravity fields.
Uplink Operations - Mission Sequence Subsystem (ULO-MSS) internal status meetings have assessed progress towards the MSS D8 software delivery date in May of this year. While some threats were identified, there was only one task that could not be handled within the current ULO-MSS margin policy. Additional analysis incorporating new information indicates that the work can probably be done within the policy if some tasks are reallocated.
After review at a previous Cassini Design Team meeting (CDT), comments have been incorporated and a new plan designed to deal with system-level vs. instrument internal commands. The revised plan was presented at this week's CDT.
Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.
Cassini Mission to Saturn and Titan
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration