Cassini Significant Event Report

For Week Ending 07/04/03

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Tuesday, July 1. 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.


On July 1, Cassini was exactly one year away from Saturn Orbit Insertion (SOI). Next year the spacecraft will complete a 6.7-year interplanetary journey, and begin orbital operations.


On board activities this week included clearing of the ACS high water marks, Radio and Plasma Wave Science (RPWS) High Frequency Receiver calibrations, and an RPWS periodic instrument maintenance. This week Cassini passed through a Sun - Earth - Probe angle of 4.0 degrees down to minimum separation of 0.344 degrees. When the separation angle reached about 3 degrees, the project began uplinking a command file consisting of 10 no-op commands sent every 5 minutes. The file is uplinked 10 to 20 times daily. These commands have been sent to the spacecraft each time Cassini enters Solar Conjunction. The purpose of the test is to accumulate statistics for uplink reliability at decreased separation angles. SOI will occur on July 1, 2004, and conjunction will follow within 7 days. Knowledge of how conjunction affects commanding will be crucial at that time.


Radio Science Subsystem (RSS) personnel continue to concentrate on characterizing the anomalous behavior of the Ka-Band Translator (KaT) for the on-going Solar Conjunction Experiment #2. The KaT continues to operate in its bad region.


Simulation coordination meetings for C39 were cancelled after it was determined that activities in the background sequence did not require Integrated Test Laboratory (ITL) testing. Trajectory Correction Maneuvers (TCM) 19a and 19b which occur in this sequence will be tested separately as mini-sequences.


Events this week for the S14 Science and Sequence Update Process (SSUP) Verification and Validation (V&V) activity included release of merged product review reports generated by the Spacecraft Operations Office (SCO), Science Planning, and Uplink Operations (ULO), release and review of an updated reference trajectory, execution of the file configuration management process, and delivery of 12 sequence change requests and review comments for the Preliminary Sequence Integration and Validation 1 phase.


SCO completed a ten-day test in the ITL of the C38 SOI Critical Sequence demonstration on July 1, exactly one year before the real SOI. The C38 SOI Critical Sequence demo will be performed on the spacecraft July 21 - August 4, 2003.


The Navigation Team has completed and documented the reconstruction of TCM 19. The results continue to indicate that the maneuver executed as planned with sub-sigma errors.


Two delivery coordination meetings were held this week, one for a Deep Space Mission System (DSMS) delivery of the Telecom Forecaster/Predictor (TFP) V 3, and the second for the Radio Science Subsystem (RSS) LMBTRK version 1.1, and an engineering version of BISTAT. The delivery of TFP provides upgrades to the DSN configuration models, as well as a few minor GUI changes. A full regression test with the previous version V2.1 showed no problems. LMBTRK is the RSS program that generates the Inertial Vector Definition (IVD) file used as input to the Pointing Design Tool (PDT) for generating spacecraft pointing commands during RSS occultations. BISTAT also generates an IVD file used as input to PDT, but it is optimized for RSS bi-static radar experiments.


Cassini Outreach conducted Solar System Ambassador training on Saturn's Rings, and gave an overview of Cassini's outreach opportunities. Approximately 50 members of JPL's Solar System Ambassador program attended.


A 2-day meeting of the K-4 education literacy partnership was held at UC Berkeley. Lesson units were reviewed, and organizational issues were addressed as the team moves toward a January 2004 final product delivery.



Additional information about Cassini-Huygens is online at http://saturn.jpl.nasa.gov.


Cassini will begin orbiting Saturn on July 1, 2004, and release its piggybacked Huygens probe about six months later for descent through the thick atmosphere of the moon Titan. Cassini-Huygens is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Office of Space Science, Washington, D.C.


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