9 Jun 2001
(Source: Jet Propulsion Laboratory)
Cassini Weekly Significant Events for 05/31/01 - 06/6/01
The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, June 6. The Cassini spacecraft is in an excellent state of health and is operating normally. Information on the spacecraft's position and speed can be viewed on the "Present Position" web page at ("http://www.jpl.nasa.gov/cassini/english/where/").
Recent spacecraft activities included an Attitude Control Subsystem (ACS) high water mark clear, a CDS error log clear, a Reaction Wheel Assembly (RWA) momentum unload, and an ACS Catbed Heater test. For this test the heaters on both thruster branches were powered on to verify that the SCO thermal heating model was correct. The test executed nominally. In addition, the Radio Frequency Subsystem began solar conjunction testing. The tests began on Thursday May 31 and will continue through the end of superior conjunction in the first week in June. For these tests commands are uplinked at 250 and 500 bits per second. The results will help the Spacecraft Operations Office (SCO) plan for Saturn Orbit Insertion, which occurs near superior conjunction.
Sequence development is under way for the Probe S-band carrier signal test to be carried out during C26 in mid June. All inputs from SCO, RSS and the Probe have been received. The sequence products will be released for review at the end of this week with a command approval meeting set for the following week.
The Huygens Recovery Task Force held a two day meeting in Noordwijk, the Netherlands. Excellent progress is being made in finding a solution for the relay link problem, and a summary report will be made to the full PSG at the Oxford meeting later this month.
The C28 SPVT Project Briefing was given by Science Planning. The project has approved the integrated plan for implementation. Science turns on thrusters needed to accomplish interplanetary cruise fields and particles data collection will be performed at slower turn rates in order to minimize hydrazine usage. The current sequence has four 90 degree and one <1 degree turns on thrusters to accomplish these measurements.
Working group meetings and telecons were held for the Titan Orbiter Science Team (TOST), the Satellite Orbiter Science Team (SOST), the Atmosphere Working Group (AWG), and the Rings Working Group (RWG). The TOST focused on finalizing the integration of the first 10 Titan flybys and preparation of the TOST report to the Planetary Science Group (PSG). The TOST is looking for PSG approval of these plans at the Oxford meeting to be held on June 18-22.
Instrument Operations (IO) and the Multi Mission Image Processing Laboratory processed and delivered 238 ISS Photometric Calibration and Dark Frame images produced in the C26 sequence.
Mission Planning activities this week included kick off of a task to assemble and manage the propellant budget for cruise and tour, completion of Revision M of the Mission Plan, and publication of the "Mission Plan Quick Reference Guide." The reference guide is being published for the first time and is a very useful document providing all the updated tables and charts from revision M of the Mission Plan. Both documents will soon be available from the Cassini Electronic Library (CEL).
Mission Assurance and Systems Engineering signed off the updated Anomaly Reporting Plan. This plan documents the process by which Cassini uses the Institutional Problem Reporting System for anomaly documentation, resolution, corrective action, and verification. The Program recently approved changes to the existing process and has begun using the updated process.
Revision G of the Cassini Anomaly Response Operations Plan has been signed off. The document will be available from the CEL next week.
More than 20 scientists presented preliminary results from last winter's Jupiter flyby during meetings of the American Geophysical Union in Boston this week. Among them were sixteen scientific papers about Cassini results from that encounter. Cassini flew past Jupiter in December 2000 for a gravity assist to reach Saturn. Researchers took the opportunity to study the giant planet from different vantage points by also using NASA's Galileo spacecraft, plus other spacecraft and ground-based telescopes, in coordination with Cassini's Jupiter observations. A list of the papers presented is available at
More information about the joint Cassini and Galileo studies of Jupiter is available at http://www.jpl.nasa.gov/jupiterflyby.
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