5 Nov 2004
(Source: Jet Propulsion Laboratory)
Cassini Significant Events for 10/28/04 - 11/04/04
The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, November 3. 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 .
With the Titan-a flyby now past, science activities this week turned to a variety of other observations. The Ultraviolet Imaging Spectrograph (UVIS) worked to determine the flux of impactors on the rings, and took mosaics of the inner magnetosphere in order to determine the density of neutrals. The Composite and Infrared Spectrometer (CIRS) monitored the F-ring, and performed observations to determine Saturn's atmospheric composition. The Imaging Science Subsystem (ISS) took spoke movies and continued to take images of small satellites for orbit determination purposes.
The suite of Magnetospheric and Plasma Science (MAPS) instruments continued their magnetosphere boundaries investigation in the dawn sector at southern latitudes and at a variety of radial distances. Once outside of the magnetosphere, they began monitoring the solar wind.
Orbital Trim Maneuver(OTM)-5, the Titan-A cleanup maneuver, was performed on October 29, 2004. This maneuver was performed to "cleanup" trajectory changes caused by the normally occurring delivery dispersions to the October 26 flyby of Titan. OTM -5 was a main engine burn of 4.6 seconds duration, giving a delta-V of 0.64 m/sec.
Additional activities on board the spacecraft included the uplink and execution of commands to normalize ACS A8.7.1 and CDA 9.2.4 Flight Software (FSW). The spacecraft was designed to be able to carry more than one version of FSW for testing purposes. To normalize FSW means to copy one version to all four partitions and to set them "equivalent". If there are bit errors in the partitions, the CDS flight software is able to check all four partitions and put together one clean copy of the software. The software is required to be normalized and equivalent when running a critical sequence such as Saturn Orbit Insertion in June of this year or Probe Relay in January 2005.
Several project members supported the kickoff meetings for the Cassini-Huygens Mission Risk Review (MRR) held on October 21 and 22. The MRR is being convened to revisit and assess the end-to-end key risk areas, mitigations and residual risks associated with the probe mission, and to validate that all significant risk issues have been identified and assessed.
A probe end-to-end sequence validation test began execution in the Integrated Test Lab (ITL) this week and will continue for the next two weeks.
Sequence development is ongoing for tour sequences S06 through S12, and S37 through S40.
A Final Sequence Integration and Validation Sequence Change Request (SCR) approval meeting was held as part of sequence development for S06. Also in support of S06 the Titan-b flyby was tested in the ITL and went very well.
For S07, the Preliminary Sequence Integration and Validation (PSIV) cycle 2 sequence products were released, and all new real-time commands needed for the probe mission have been built and published to the Program file repository. They are now being utilized in the SCO ITL Probe Mission end-to-end test. Navigation, Spacecraft Operations Office (SCO), Science Planning, and Uplink Operations personnel have worked out a development and uplink schedule for the three real-time Optical Navigation sequences following probe release. This time line will be presented at the PSIV SCR approval meeting.
The S07 simulation coordination meeting and the simulation procedure review meetings have been cancelled because most of S07 is already undergoing simulation in the Probe end-to-end test currently running in ITL. An additional Iapetus science mini-sequence will have its run in late December.
Meetings to disposition one waiver request and 16 SCRs were held in support of S08, and the full set of Sub Sequence Generation products has been released for review.
All port #1 reports were delivered as part of Science Operations Plan (SOP) update for S09, and a kick-off meeting was held for SOP update of S10.
The Titan Orbiter Science Team re-integrated the Titan-3 flyby sequence last week. This flyby will now be a RADAR pass instead of a Radio Science Subsystem (RSS) pass. The radio science occultation on this flyby was lost due to the recent update of the reference trajectory. The Satellite Orbiter Science Team met this past week to discuss the RSS proposal for re-integrating the Enceladus flyby in S08 to acquire a radio science Earth occultation. After much debate the Project Scientist decided to keep the science plan as currently integrated.
Titan-a was the subject of this week's Mission Planning Forum. Mission Planning and the Navigation, Propulsion, and ACS teams gave presentations. Topics included Ta execution, preliminary estimates of the actual flyby trajectory, hydrazine usage, measured attitude control performance, special playback overview and results, and Tb applicability.
Delivery coordination meetings were held for Automated Sequence Processor (ASP)/ Electronic Command Request Form (eCRF) v1.3.3, Mission Sequence Subsystem (MSS) D10.4, and for the SCO tools CK compare and pef powercheck.
The primary driver for the release of MSS D10.4 is to provide functionality to support Radio Science Inertial Vector Definition (IVD) targeting, including a new target option, RSSIVD, a new module, RSSIVD_TARGETING, and related updates to Pointing Design Tool, the Sequence Generator and the SEG command table.
Saturn Observation Campaign members organized over 75 events in 31 states and 7 countries on October 27, 2004 to show the total lunar eclipse to their communities. Lunar features named after Christiaan Huygens and Giovanni Cassini are visible on Earth's moon through modest telescopes. The Saturn Observation Campaign "Photo Gallery" contains images of these features, photographed by a Saturn Observation campaign member from Australia, at http://soc.jpl.nasa.gov/experience/gallery.cfm. Many of the campaign hosts also used the new images of Titan from the October 26 Titan flyby in their programming. A summary of these reports is on the main Cassini webpage in a feature titled Night of the Two Moons. Go to http://saturn.jpl.nasa.gov/news/features/feature20041101.cfm.
The JPL Education Office presented a Cassini-Huygens Mission to Saturn workshop to Pasadena, California third and fourth grade teachers this week. The workshop featured Reading, Writing and Rings, produced as a collaboration of the Cassini-Huygens mission, the JPL Education Office, and writing experts from the Caltech, UC Berkeley and the Bay Area Writing Project. This curricular unit was designed using a language arts format to allow students to experience the wonder of the Cassini-Huygens mission. The Reading, Writing and Rings program is available for download from: http://saturn.jpl.nasa.gov/education/edu-k4.cfm.
Multiple news articles and papers appeared all over the world last week in response to Cassini's T-a flyby. Subjects ranged from discussion of images of Saturn's moon Prometheus stripping material from its neighboring ring, to speculation on the existence of liquids on Titan and their possible organic content.
Extensive information on the Cassini-Huygens mission including an electronic copy of the press kit, press releases, fact sheets, status reports, briefing schedule and images is available on the Internet at http://saturn.jpl.nasa.gov.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter.