Cassini Significant Event Report

For Week Ending 08/15/03

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Tuesday, August 12. 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.

The C38 background sequence concluded this week with playback of science data recorded during Saturn Orbit Insertion Demonstration, a Magnetospheric Imaging Instrument (MIMI) Instrument Expanded Block (IEB) load test and a Radio and Plasma Wave Science (RPWS) High Frequency Receiver calibration. The flight team sent real time commands to power on the Ion and Neutral Mass Spectrometer (INMS) and load the instrument with IEBs. The team also loaded the INMS flight software (FSW) onto the Solid State Recorder (SSR).

C39 background sequence was radiated to the spacecraft on Thursday, August 7, and began execution on Sunday August 10. C39 contains numerous instrument checkout and calibration activities that must be performed prior to the approach science phase which begins in January of 2004.

Initial activities included IEB loads from the SSR for the Cassini Plasma Spectrometer (CAPS), Ultraviolet Imaging Spectrometer (UVIS), and RPWS, a Magnetometer calibration, a Composite Infrared Spectrometer (CIRS) module test, CAPS and Visual and Infrared Mapping Spectrometer (VIMS) FSW uploads. Also uplinked were a mini-sequence for INMS FSW checkout, pressure test, and all C39 INMS checkout activities, and a RPWS high rate observation and IEB exercise.

The INMS team reports that the instrument is now on, in sleep mode, and operating normally. The INMS instrument was last active during the instrument checkout period in cruise sequence C11 in January of 1999. The instrument has been off since then per plan.

A kick-off meeting was held for the start of the Science Planning Virtual Team process for cruise sequence C42. C42 is the first of three approach science sequences just prior to the start of tour operations. This is an intense period of time while the flight team transitions between cruise and tour processes and procedures, and we gather valuable science and navigation data as we draw closer to Saturn.

The science and engineering teams have delivered sequence products for preliminary port one of the science operating plan for tour sequences S03 and S04, and port two for cruise sequence C40.

The Science Planning team presented an overview of the aftermarket process. Cassini personnel are currently creating the basic commands for pointing, telemetry, and power to control the spacecraft for each of the 41 sequences in the four-year tour. When the process for a sequence concludes, the sequence is archived for as long as two to four years. During this time, science and engineering teams may work on the liens identified and make a small number of changes to the baseline plan. New discoveries and changes in the spacecraft or instruments may also necessitate a change in the plan. The presentation outlined guidelines and constraints that will govern this work, and summarized the five week aftermarket process where changes are prioritized and approved/disapproved so that a complete package may be created for the science operations plan (SOP) update.

A Software Review Certification Requirement delivery meeting was held for the MIMI v7.0.0 FSW build. The board granted preliminary approval of the FSW for preparation of the uplink files with final approval to occur after completion of an additional regression test and update of the release documents.

The Multi-mission Image Processing Laboratory (MIPL) version D30 software is now officially in use as the operational software set. All Cassini MIPL tour hardware has been configured and is now on-line. This includes seven Sun Blades for telemetry processing, and eight terabytes of storage for the Imaging Science Subsystem (ISS) and VIMS life-of-mission storage. The multi-mission database server machine was also upgraded to meet performance needs.

System engineering held a Delivery Coordination Meeting (DCM) for three Spacecraft Operations Office tools. The MAPDF_GEN Generator (MAPDF_GEN): is used to create a Maneuver Performance Data File (MAPDF) for use by navigation in the maneuver design process. The Maneuver Design tool (MDT) determines the commands necessary for the spacecraft to perform a trajectory correction maneuver. The Best Estimate Conic (BECON) tool determines a single best-fit conic orbit for the orbiter as it flies past Titan during the Huygens probe mission. The orbit is used on board the spacecraft to provide pointing control.

A DCM also was held for the Kinematic Prediction Tool (KPT) v9.2. The DCM accepted the delivery but agreed to wait 1-2 weeks for additional testing prior to installation on the operations network.

Additional information about Cassini-Huygens is online at

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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