Cassini Significant Event Report

For Week Ending 08/02/02

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Tuesday, July 30. 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 board activities this week included uplink of real-time commands to read out data from the AACS Stellar Reference Unit table, and clear the AACS High Water marks. Additional instrument activities included calibrations of the Radio and Plasma Wave Science (RPWS) High Frequency Receiver, Ultraviolet Imaging Spectrograph (UVIS) periodic instrument maintenance, and instrument flight software normalization for RPWS and UVIS.


The data from the 2002 Solar Conjunction Experiment performed in June and July have been processed, and preliminary analysis shows a successful investigation, despite initial problems with the ground instrument. An estimation of the effect has been determined and will be refined as the data are calibrated further.


One of the goals of the Cassini Solar Conjunction Experiment is to measure the effect of the solar gravity on the path of electromagnetic radiation. Propagating photons of the radio signal are deflected and delayed by the sun. Predicted by Einstein in 1916, this was measured during a solar eclipse in 1919 as the first experimental test of General Relativity. A violation of General Relativity might be due to scalar fields remnant of the Big Bang, and its detection would have crucial implications in physics. Cassini can measure the gravitational deflection utilizing a highly accurate Doppler system at X- and Ka-bands, potentially to a level of one hundred times better than past experiments.


The Multi-mission Image Processing Laboratory software version 28 was installed for operations use this week. This delivery supports Cassini cruise and is the first of three phased implementations to include support for tour. Also included are ground processing updates to support changes to VIMS flight software, Video Information Communication and Retrieval multi-mission routines for project recognition, and label decoding and camera parameter updates to support Cassini. With this change, Cassini gains access to numerous image analysis tools.


Instrument Operations (IO) personnel attended a Planetary Data System (PDS) Management Council meeting. Cassini archive status was presented, and a discussion held on archive challenges from a project point of view. PDS provided a demonstration of the new PDS archive and distribution system. The IO representative was very impressed and recommended a demonstration also be given at the next Cassini Project Science Group Meeting to be held at JPL in October 2002.


During the transition from reaction wheel to thruster control last week, the Attitude Control team used the opportunity to perform a friction test on the reaction wheels. The test carefully examined the "spin down" characteristics of each of the wheels. The team has processed the data and concluded that the reaction wheels are continuing to perform normally.


A series of meetings has been held to plan the implementation of Prime/Rider instrument coordination within Cassini. The preliminary results will be presented at next week's Instrument Operations Working Group meeting.


Uplink Operations hosted an SSR Management Tool (SMT) development meeting to work with the Spacecraft Office (SCO), Science Planning, and Mission Planning on determining what updates will be included in the D9.0 delivery of SMT.


System Engineering (SE) has completed work with the SCO CDS Team to clean up the flight rule (FR) allocation matrix, prioritize FR fixes in software, and review the sequence checklist. Similar activities for the remaining SCO subsystems are in work. In addition, SE presented a proposal for Level 4 Verification and Validation plans at the System Engineering Round Table meeting.


Mission Assurance convened a quarterly Risk Team meeting to assess the remaining six cruise risks as well as risks associated with the Huygen's Probe mission. Several new risks were identified, existing risk descriptions were refined, and action was taken by the Spacecraft Office to rework Probe Mission risks completely. Quarterly meetings are part of the on-going Risk Management process on Cassini during Flight Operations.


The Cassini Program Outreach Team has selected a vendor to produce the planetarium show "RingWorld." The show will debut in January 2003. Produced in multiple formats, it will be made available to over 950 planetariums in the USA, as well as community colleges, schools, youth groups, and online via the Cassini web site. A Spanish language translation of this show will also be produced. A portion of the show will talk about the Deep Space
Network. The DSN will cost share and place a copy of this show in their visitor centers in Australia, California, and Spain.


Cassini Outreach has updated the Titan Landing Site graphic to reflect the new landing site and date for the Huygens Mission. This new graphic has a reference number of P-50940, and is available through Finley-Holiday at http://finley-holiday.com or by calling (800)345-6707. The image will be placed on the gallery portion of the Cassini web site, and will also be part of Huygens related slide sets.



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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