Cassini Significant Events for 12/21/05 - 01/04/06 The most recent spacecraft telemetry was acquired Wednesday, January 4, from the Goldstone tracking stations. 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 . Cassini Significant Events 12/21/05 - 01/04/06 Due to the holidays, no Significant Events report was generated last week. The report this week covers 15 days from December 21, 2005 through January 4, 2006. Hang on, it's gonna be a long report! Wednesday, December 21 (DOY 355): Uplink Operations personnel sent commands to the spacecraft today to perform an on-board live Inertial Vector Propagation (IVP) update. The update will execute on DOY 358/359 and will update vectors for Dione, Tethys, Enceladus, Saturn, and Telesto. Science activities today included a distant observation of Hyperion involving all Optical Remote Sensing (ORS) instruments, and Imaging Science Subsystem (ISS) tracks of many small moons as part of the Satellite Orbit Determination Campaign. Thursday, December 22 (DOY 356): A preparation meeting was held today for Orbit Trim Maneuver (OTM) 047. The maneuver is scheduled to execute on December 29. Friday, December 23 (DOY 357): The RADAR instrument performed an engineering test that will address radiometer calibration issues using Saturn as a reference target. Saturday, December 24 (DOY 358): Today marked the start of the annual sequence development hiatus. The Aftermarket, Science Operations Plan Update (SOPU), and Science and Sequence Update Process will pause activities from today through January 2, 2006. The processes will begin again on January 3. Early on in the tour, program management identified the difficulty of trying to conduct this type of development over the Christmas and New Year's holidays due to varying vacation schedules and the different holiday schedules of our foreign partners. As a result, each year a pause is built in to the development schedules that lasts for about two weeks during this time. Operations work continues, OTMs, real time commanding, downlink, etc. It's just these three processes that pause. Well, OK, we do cancel a few meetings(:>) Non-targeted flybys of Enceladus and Pallene occurred today. The Enceladus flyby was at an altitude of 93,984 km. Whoa. It's been a year. Today is the one-year anniversary of the Huygens Probe release! For those of you who would like to remember where we were last year at this time, here is an extract from the Significant Events report for December 24, 2004, Christmas Eve: Everything looks good and nominal. JPL provided dinner for those of us who had to work. There was slight congestion at the dessert table, but everything else was nominal. All Orbiter instruments reported in. Everyone is in the correct configuration and is ready for release. The project set up a conference line so that Cassini flight team members who are not working the event but who came in anyway to show their support can listen in on events as they unfold. The Huygens Probe was successfully deployed from the Cassini Orbiter! Navigation and Spacecraft Operations Office teams confirmed the nominal separation of the Probe at 7:24 Pacific time. The Probe is now in free flight at a spin rate of 7.5 rpm as detected by the Magnetometer Subsystem. All systems performed as expected, there were no problems reported with the Cassini spacecraft, no red alarms, no fault protection. Congratulations everyone! After release, the Uplink Operations (ULO) sequence lead called for the start of planned Probe optical navigation imaging. This is a 4.5 hour process. Currently we are on schedule. The head of the Huygens Spacecraft Operations Unit expressed his thanks to the team for a wonderful adventure in the exploration of Saturn. Huygens personnel are now waiting with great expectation for the Probe descent on January 14, 2005. Sunday, December 25 (DOY 359): Non-targeted flybys of Helene and Telesto occurred today. Science activities today included a Composite Infrared Spectrometer (CIRS) Saturn Tethys F-Ring movie, and the first of three Radio Science Subsystem (RSS) Gravity Science Enhancement passes on and after Christmas - DOY 359, 361, and 362. These are additional downlink passes at Ka-band to obtain Titan gravity science. Monday, December 26 (DOY 360): On December 26, Cassini flew by Titan at an altitude of 10,409 kilometers. At this time, the Imaging Science Subsystem (ISS) acquired a mosaic of Titan's albedo features Aztlan and Quivira, Bazaruto and Elba Faculae, and Omacatl Macula, at low phase angles of approximately 25 degrees and pixel resolution scales of approximately 700 to 450 meters. This ISS observation also overlaps eastern portions of the Titan A and Titan 3 RADAR swaths. The Composite Infrared Spectrometer (CIRS) obtained information on trace constituents in Titan's stratosphere. An integration of the limb obtained information on CO, HCN, and CH4. The Ultraviolet Imaging Spectrograph (UVIS) used its Hydrogen-Deuterium Absorption Cell (HDAC) to conduct key measurements of the Titan atmosphere as well. Measurements of the D/H ratio in the Titan atmosphere will yield clues to the formation and history of Titan and the Saturnian system. The Visual and Infrared Mapping Spectrometer (VIMS) also obtained a medium resolution regional map using the same observing strategy as the previous Titan flyby. Moreover, this Titan flyby presented an excellent diametric wake crossing at 5.04 Titan radii downstream for all of the Magnetospheric and Plasma Science (MAPS) instruments, which will be ideal for comparisons to the Voyager-1 Titan flyby data set. Cassini's encounter possessed similar observing geometry as the encounter of Voyager-1 in November 1980. Especially with the increased capability of Cassini, the MAPS instruments will finally be able to compare the Cassini and Voyager data sets to further study Titan's atmospheric loss and the structure of Titan's plasma wake. But more importantly, this flyby will represent the only crossing of Titan's magnetotail at an intermediate distance in the Cassini tour, which will be highly valuable for the study of the formation of Titan's magnetotail as a function of distance. Tuesday, December 27 (DOY 361): It was reported today at the weekly Operations Status and Coordination meeting that data from the Titan 9 flyby yesterday has been successfully downlinked. In particular UVIS reported that they had received the entire HDAC observation data set. There were several gaps of less than one minute due to some problems at DSS-14, but nothing that required the implementation of the contingency plans and procedures that had been developed and reported on last week. Wednesday, December 28 (DOY 362): An article was presented in the December 27 Aerospace Daily & Defense Report stating that NASA is considering a two-year extension to the Cassini mission that would extend the exploration of Saturn and its moons through 2010. "NASA has given us some additional funding to study what the options would be" for the extra two years, said Bob Mitchell, Cassini program manager at the Jet Propulsion Laboratory in Pasadena, Calif. The spacecraft's lifetime ultimately will be determined by what kind of follow-on mission, if any, is carried out. "If we put together a tour that would look very much like what we're doing now - a Titan flyby every month or so and an icy satellite flyby stuck in here and there - then another two years would probably about run us out of propellant. However, if the spacecraft is placed in a fairly uneventful orbit and dedicated to studying Saturn's ring system, for example, it could likely last years longer." he said. Thursday, December 29 (DOY 363): OTM-047 was successfully performed today. This was the cleanup maneuver from the Titan-9 flyby that occurred on December 26. The reaction control subsystem (RCS) burn began at 7:55 pm Pacific Time. Telemetry obtained immediately after the maneuver showed the burn duration was 198.9 seconds, giving a burn delta-V of 0.179 m/s. All subsystems reported nominal performance after the OTM. Beginning today and running through January 4, science activities involve the entire suite of MAPS instruments simultaneously performing low-rate outer magnetospheric surveys to observe the variability of magnetospheric boundaries at a variety of radial distances. Optical remote sensing activities include ISS observations of a mutual event capturing Janus crossing Dione, many photometric calibrations done with a variety of stars, and narrow-angle camera lightning searches in Saturn's northern hemisphere. Finally, UVIS will obtain mosaics of Saturn's inner magnetosphere. Friday, December 30 (DOY 364): Today is the fifth anniversary of the Cassini flyby of Jupiter on December 30, 2000. Saturday, December 31 (DOY 365): Documenting a year at Saturn, Astronomy Picture of the Day selected for their picture today an image of Saturn's moon Dione in front of edge-on rings and the cloud tops of Saturn draped with broad ring shadows. It's very cool! 2006 Sunday, January 1 (DOY 001): This feels more like a Christmas present than a report of what to expect in the New Year! In 2006 Cassini will execute all or part of 10 on-board sequences from S17 through S26, and all or part of 18 orbits of Saturn from Rev 19 through Rev 36 will occur. During this time there will be 13 targeted flybys of Titan including T10 through T22, 20 non-targeted flybys including Helene, Rhea, Polydeuces, Tethys, Telesto, Titan, Atlas, Calypso, Enceladus, Methone, and Dione, 39 opportunities for maneuvers from OTM-048 through OTM-086, the start of extended mission development will begin in January, one superior conjunction will occur in August, and finally a partridge in a pear tree will occur next December. (:>). Should be a busy year. Monday, January 2 (DOY 002): OTM-48, originally scheduled for today, was cancelled back in early November along with OTM-54 and OTM-60. This was done because there were only three DSN tracks between the cleanup and apoapsis maneuvers, delivery errors did not improve after the apoapsis maneuver, and the maneuvers would be difficult to cancel in real time. The delta-V cost was about 0.8 m/sec. The capability to execute a maneuver on the planned prime and backup passes was retained but proved unnecessary for OTM-048. Spacecraft Operations and Navigation will re-evaluate OTMs 54 and 60 as necessary. Tuesday, January 3 (DOY 003): Dark terrain on Iapetus was selected as Astronomy Picture of the Day today. Flight software (FSW) normalization for CIRS and the Cassini Plasma Spectrometer (CAPS) was begun today and will continue through January 6. There are four copies of an instrument's FSW in partitions 0 through 3 on each SSR. When the instrument team has a new version of FSW, it is uploaded into 2 of the partitions, in this case partitions 2 and 3, leaving copies of the old software on 0 and 1. The old version is retained until the instrument team performs a flight software checkout and confirms the new version. After the confirmation, "normalization" is performed where the new version replaces the old version in the remaining partitions on both SSRs, in this case 0 and 1. Wednesday, January 4 (DOY 004): The Science Operations Plan Update process for S20 kicked off today. The process will run for five weeks and will conclude on February 10. Wrap up: Check out the Cassini web site at http://saturn.jpl.nasa.gov for the latest press releases and images. 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. --- To unsubscribe from Cassini Spacecraft Updates, send a message to leave-cassini-@xxxxxxxxxxxxxxxxx --- Visit the JPL Cassini home page for more information about the Cassini Project: <http://saturn.jpl.nasa.gov/>
