Cassini Significant Events for 01/16/08 - 01/22/08 The most recent spacecraft telemetry was acquired on Tuesday, January 22, from the Goldstone tracking complex. The Cassini spacecraft is in an excellent state of health and all subsystems are 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. Wednesday, January 16 (DOY 006): The final S37 sequence approval meeting was held today. The sequence will be uplinked to the spacecraft on Sunday, Jan. 20, and begin execution on Tuesday, Jan. 22. The S42 Spacecraft Engineering Activities Review was also held today. The review addressed activities to occur in the first sequence of the proposed extended mission. S42 begins execution on July 1, 2008. Analysis of data from the T38, T39, and T40 Titan flybys was presented today by Ion and Neutral Mass Spectrometer (INMS), Attitude and Articulation Control Subsystem (AACS), and Navigation teams at a Titan Atmosphere Model Working Group (TAMWG) meeting. The conclusion was that the atmospheric data from these southern hemisphere flybys were generally consistent with previous flybys in the northern hemisphere and that there is no indication of any major atmospheric differences in time or hemisphere. There is some indication that southern hemisphere passes might be experiencing slightly less density than northern hemisphere passes, but the data are still too sparse to confirm that. There are small but unexplained differences when comparing the current passes to passes with similar altitude and latitude in the northern hemisphere relative to N2, CH4, and H2 abundances. T36 data remains the lowest density measured under 1100 km. The next TAMWG meeting will be held concurrently with the Project Science Group meeting in June of this year. At this meeting the TAMWG will review the entire baseline mission set of flybys to evaluate the safety of planned proposed Extended Mission flybys, and to recommend whether to adjust the current atmosphere model. Thursday, January 17 (DOY 017): Science observations today include Imaging Science (ISS) and the other Optical Remote Sensing (ORS) observations of Rhea at low phase. ISS will also track the transit of Janus across Dione and make observations of the diffuse rings at low phase and elevation. The Visual and Infrared Mapping Spectrometer (VIMS) will observe the rings as the spacecraft crosses the ring plane to obtain more data for a ring plane-crossing movie. Friday, January 18 (DOY 018): Over the weekend from late Saturday to early Sunday morning, Spacecraft Operations will perform an annual Stellar Reference Unit calibration. Monday, January 21 (DOY 021): While the Composite Infrared Spectrometer (CIRS), Ultraviolet Imaging Spectrograph (UVIS), and ISS were monitoring the F-ring, the Cosmic Dust Analyzer (CDA) was performing a software checkout/functional test. The text exercised version 12.0 instrument flight software (FSW) that was uplinked last week. A FSW demonstration is planned for the 27th and again in early February if needed. Cassini's 57th orbit of Saturn began late Monday with the spacecraft at an apoapse distance of 30.1 Rs and an orbit inclination of 46.6 degrees. Tuesday, January 22 (DOY 022): A non-targeted flyby of Titan occurred today. Near the end of S36, the RADAR instrument began warming up and calibrating for science data collection. By acting like a camera that uses microwaves instead of visible light, RADAR studied Titan's northern hemisphere providing coverage of various northern latitudes along with some associated longitude variation. To obtain the correct polarization for these observations, RADAR was in control of both the primary and secondary axes of the spacecraft. The S36 sequence concluded and S37 began execution today at 2008-022T13:35:00 Spacecraft Event Time. The sequence will run for 25 days and conclude on February 16, 2008. During that time there will be nine non-targeted flybys - two of each of Titan, Atlas, Epimetheus, and Pandora, and one of Prometheus. Only one maneuver is scheduled for S37, OTM-144. Key events for this sequence include a prime reaction wheel friction test, periodic engineering maintenance, and AACS A8.7.6 flight software normalization. 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/>
