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Significant Event Report for Week Ending 3/26/2004

Cassini Significant Event Report

For Week Ending 03/26/04

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Monday, March 22. 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 .

The primary activity this week was the execution of the 13th in-flight Huygens probe checkout and a special test of the Probe Mission Timing Unit (MTU). The performance of the Huygens engineering subsystems and instruments during the checkout was as expected. The flow of data from JPL to the Huygens Probe Operating Center in Darmstadt went very smoothly. The MTU is the timer which is set just prior to probe release. Drawing minimal power, it counts down to a fixed time before probe entry at Titan and then initiates the powering on of the Huygens avionics and instruments. The test validated the ground system's process for setting the timer and also measured the timer's drift rate. All aspects of the test were nominal.

Additional on-board activities included Magnetospheric Imaging Instrument (MIMI) flight software (FSW) normalization, Ion and Neutral Mass Spectrometer (INMS) load of version 7 FSW to the SSR, and powering off of the Cassini Plasma Spectrometer (CAPS).

Sequence development activities for C44 concluded this week. The Final Sequence Integration and Validation (FSIV) phase sequence change request (SCR) and waiver approval meeting was held with two SCRs and one waiver approved. A Command Approval Meeting was held for Instrument Expanded Block (IEB) files to be uplinked to the spacecraft for Composite Infrared Spectrometer (CIRS), CAPS, Ultraviolet Imaging Spectrograph (UVIS), Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS), Radio and Plasma Wave Science (RPWS), and INMS. The C44 final sequence approval meeting was also held this week. Uplink of IEBs is scheduled for March 25, and the background sequence on March 27. C44 will go active on April 1.

Development of S01, the first tour sequence, continued this week. The Project came to closure on the Phoebe pointing design issue associated with Kinematic Prediction Tool / Flight Software Development System pointing profile. The Phoebe design will remain as is. The Subsequence Generation Phase has now concluded with all teams delivering their subsequences, and generation of the Preliminary SIV Cycle 1 merged sequence products.

Since the start of approach science in January of this year, 1597 ISS images have been acquired along with 627 VIMS cubes.

The Science Operations Plan Update process for S02, which includes the science occurring during and after the Saturn Orbit Insertion burn, had its preliminary port 1 delivery this week.

Tour Science Plan presentation #4 to the flight team was part 1 of 2 parts on the Titan Orbiter Science Team plans for tour. This team was responsible for science integration of the 45 targeted Titan flybys during the prime mission.

Thanks to Mission Planning team members, the Cassini real-time activity display showing a continuously updating graphic of Saturn and its satellites in relation to the current position of the Cassini spacecraft and instruments' fields-of-view has been made available on JPL TV channel 35 and the Space Flight Operations Facility gallery.

A readiness review was held for Cassini version A8.6.7 flight software. The review went well with only 7 Recommendations for Action generated, none of which will affect upload of the flight software towards the end of April of this year.

Development has been completed and system testing begun for Mission Sequence Subsystem (MSS) software version D10.3. This version includes new functionality for the Pointing Design Tool and updated maneuver blocks in Sequence Generator (SEQGEN).

A delivery coordination meeting was held for Navigation software version T1.2, and Spacecraft Operations Office tools ALF_TOOL version 10.2, and Main Engine Pre-aim Utility (MEPU) version 1.0. The MEPU tool calculates the engine pre-aim vector for a Trajectory Correction Maneuver (TCM) based upon telemetry data from a previous maneuver. MEPU computes the average of the unit thrust vector within a given time window, and can also adjust the pre-aim vector for mass shifts from events such as probe release.

The five so-called naked-eye planets - Mercury, Venus, Mars, Jupiter and Saturn - reunited in the night sky, giving spectators an opportunity to see Earth's closest companions. The gathering will be visible every night for an hour after sunset, beginning around March 22 and lasting about two weeks. For more information go to: http://www.jpl.nasa.gov/news/features/fabfive.cfm

Bands and spots in Saturn's atmosphere, including a dark band south of the equator with a scalloped border, are visible in the most recently released image from the Cassini-Huygens spacecraft. The narrow-angle camera took the image in blue light on Feb. 29, 2004. The distance to Saturn was 59.9 million kilometers. The image scale is 359 kilometers per pixel. For more information go to:

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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