Cassini Significant Event Report

For Week Ending 09/03/04


The most recent spacecraft telemetry was acquired from the Madrid tracking station on Tuesday, August 31. 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 http://saturn.jpl.nasa.gov/operations/present-position.cfm .


Last week Cassini passed apoapsis, the farthest point from Saturn in its orbit, and in this case, in the entire tour. It also marked the transition between Rev 0 and Rev A - Rev being another term for orbit - and marks the start of Cassini's approach to Titan for the Titan-a encounter in October. At its present position, Cassini is outside Saturn's magnetosphere. From this vantage point the Magnetospheric and Plasma Science (MAPS) instruments continued their campaign to study the influence of the solar wind on Saturn's aurora. The combination of this large distance and the quality of the imaging subsystem allows an opportunity to obtain mosaics and movies over large areas that will be used to study storms and dynamics in Saturn's atmosphere.


This week the optical remote sensing (ORS) instruments scanned Saturn's south pole, obtained ultraviolet mosaics of Saturn's magnetosphere, and observed Saturn's aurora. The imaging cameras obtained mosaics and movies of the rings and Saturn's south pole, and the Magnetospheric Imaging Instrument (MIMI) imaged the magnetosphere and observed the solar wind and pickup ions.


Additional activities included uplink of a file to activate an internal sequence for the Cosmic Dust Analyzer, and a time-of-flight unit tweak for the Cassini Plasma Spectrometer to obtain higher resolution data during their upcoming calibration.


Spacecraft Operations Office activities this week included a reaction wheel assembly friction test on board the spacecraft, and a test of Orbit Trim Maneuver 003 (OTM) in the Integrated Test Laboratory. The results from the friction test are being analyzed currently. Friction tests are performed every three months on the prime wheels 1,2 and 4 to trend their performance. OTM-3 will be tested twice, once using the Reaction Control Subsystem and the second time using the main engine. The benefit of using the main engine for such a short burn - approximately 3 seconds - is that it allows the program to conserve the hydrazine propellant.


The Section 312 Navigation Advisory Group conducted a review of the Project's planning and preparation for the Huygens Probe mission activities. The board report is not available yet, but comments during the course of the review were generally favorable.


The sub-sequence generation products were delivered to the program file repository in support of sequence development for S05. In addition, a meeting was held to discuss simulation requirements for Titan-a Integrated Test Laboratory testing.


The Mission Sequence Subsystem (MSS) team released MSS D11 baseline plans for Project review at a Cassini Design Team meeting this week. At the same time, a discussion was held for plans and proposed features for MSS D10.3.2, D10.3.3 and D10.4 deliveries prior to the Probe Mission and leading up to the D11 delivery in April of next year.


For the most recent Cassini information, press releases, and images, go to http://saturn.jpl.nasa.gov.