Cassini Significant Events for 02/14/07 - 02/20/07 The most recent spacecraft telemetry was acquired on Tuesday, February 20, 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, February 14 (DOY 045): Testing was begun today in support of S29 in the Integrated Test Laboratory for RADAR activities for Titan 28 and Titan 29. The test will conclude on Feb. 20. The sequence leads for S29 have also reported that due to its size, the S29 background sequence will be split into two parts. A delivery coordination meeting was held today for Mission Sequence System (MSS) software version D12.1. The primary driver for the release of D12.1 is to update the maneuver main engine and reaction control subsystem nominal blocks. The flight team uses MSS during the sequence development processes. MSS generates sequence files and timelines for distribution as intermediate review products, and the Sequence of Events, DSN Keyword File, and the Space Flight Operations Schedule as formal review products. The Science Operations Plan Update process for S31 kicked off today. The process runs for approximately six weeks and will conclude on March 30. Thursday, February 15 (DOY 046): Today the Project presented a proposal for a two-year mission extension to a review board assembled by NASA HQ. Four of the project's scientists and five team members from JPL presented the details of the proposal. A report from the board to NASA is due the second week of March, and a final decision from NASA is expected nearer the end of March. A non-targeted flyby of Titan occurred today. The Spacecraft Operations Office hosted a review of engineering activities to be conducted for the duration of S33. A stellar calibration of TX Cam, a dying star nearly 1000 light years from Earth, was the object of a VIMS (Visible and Infrared Mapping Spectrometer) observation today. TX Cam is a Mira variable star with a long period variability in its brightness of 557 days. The Optical Remote Sensing (ORS) instruments with the Imaging Science Subsystem (ISS) prime observed a distant Iapetus at a very low phase angle, the angle between the Sun, Iapetus, and Cassini, of 7.4 degrees. Such high illumination emphasizes the contrast between dark and light areas. On Iapetus, the light side is nearly five times as bright as the dark side. Turning their attention to a smaller moon, the instruments participated in studying Hyperion at a distance from Cassini of just over 200,000 km, approximately the same distance as the June 2005 flyby. The Hyperion phase angle this time was 65 degrees. Planning an observation of Hyperion presents challenges due to the chaotic tumbling of that body rather than a stable and predictable rotation about an axis. Friday, February 16 (DOY 047): Immediately after the downlink of yesterday's data was complete, Cassini again pointed its ORS instruments toward Hyperion to continue observations. Then, at 2007-047T09:44:23 GMT, Cassini descended through the ring plane at a distance of 20.68 Rs. After a distant inbound flyby of Titan yesterday, this equator crossing nearly tangent to the L20 shell near midnight provided the Magnetosphere and Plasma Science (MAPS) instruments another opportunity to measure the vertical profile of the Titan torus. VIMS characterized another two stars in the infrared. Gamma Eri, a double star also named Zaurak, is a long irregular period giant with magnitude variation from 2.88 to 2.96. The second star, RX Lep, is another pulsating red giant. Saturday, February 17 (DOY 048): A new background sequence, S28, began execution on-board the spacecraft today. The sequence will run for 39 days, concluding on March 28. During that time there will be three targeted encounters of Titan and seven maneuvers numbered 94 through 100. Due to its large size, the sequence has been split into two parts. Part two will be uplinked to the spacecraft well prior to the start of execution on March 15. Science for the first few days of S28 consists of a continuation of mosaics of the entire ring system, and the Ultraviolet Imaging Spectrograph performing a stellar occultation utilizing the star Del Per. Monday, February 19 (DOY 050): Orbit Trim Maneuver (OTM) #94 was performed today. This is the approach maneuver setting up for the Titan 25 encounter on Feb. 22. The reaction control subsystem burn began at 12:45 AM PST. Telemetry immediately after the maneuver showed the burn duration was 28 seconds, giving a delta-V of 0.037 m/s, as planned. All subsystems reported nominal performance after the maneuver. 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.
