Cassini Significant Events for 02/21/07 - 02/27/07 The most recent spacecraft telemetry was acquired on Tuesday, February 27, 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 at http://saturn.jpl.nasa.gov/operations/present-position.cfm . Wednesday, February 21 (DOY 052): On Thursday, February 1, tour PF6h9 was selected as the preferred tour to be used for the extended mission proposal to NASA Headquarters. The tour has now been renamed "XM0" which is a bit less unwieldy. Development for XM0 is progressing. All tweak requests from the science community were submitted by February. 16. Tweaks will be analyzed and worked with the requesters and project to determine their feasibility. Tweaks that survive this process will be presented to the science community with two weeks for analysis towards a project-wide extended mission reference trajectory decision at the beginning of May. A decision from NASA Headquarters on the extended mission proposal made on February 15 is expected by the end of March. The most recent Cassini video update is now available and addresses the Titan 23 flyby on January 13. To access the update, link to: http://saturn.jpl.nasa.gov/multimedia/videos/video-details.cfm?videoID=146 Thursday, February 22 (DOY 053): Cassini passed by Titan today at an altitude of 1000 kilometers for the Titan 25 flyby. Spacecraft Operations reported that the peak thruster duty cycle was approximately 28 percent. The RADAR swath for this flyby was designed to cross over several prior swaths for a geodetic tie point and stereo imaging opportunities, and mapping of the polar trailing hemisphere area for possible lakes. Additional science opportunities included Imaging Science Subsystem observations at 650 m/pixel resolution in the second-most northern latitude viewed in the tour, and Composite Infrared Spectrometer (CIRS) acquisition of data for temperature maps, and mapping of the limb region for hydrocarbons. Finally, the Visual and Infrared Mapping Spectrometer obtained its first view of the upper northern hemisphere. Saturday, February 24 (DOY 055): Orbit Trim Maneuver (OTM) #95, the Titan 25 cleanup maneuver scheduled for Sunday, February 25, has been cancelled. Processing one more day of tracking data confirmed the conclusions arrived at during the Friday OTM-095 Navigation review. The orbit determination solution moved about 20 meters in the T25 B-Plane, and 12 kilometers in the T26 B-Plane. OTM-95 delta-V decreased from 165 mm/sec to 159 mm/s with a corresponding decrease in the cancellation cost from 177 mm/s to 164 mm/s. A reaction wheel bias will be uplinked to the spacecraft in lieu of the maneuver. Monday, February 26 (DOY 057): The final sequence development process for the S30 sequence kicked off today. A kick-off meeting was also scheduled today for a live Inertial Vector Propagator update to occur on March 6, targeting Rhea with CIRS as the driving instrument. Modeling results indicated that the targeting errors were very small. As a result, the meeting, the rest of the process, and the update were cancelled. Tuesday, February 27 (DOY 058): A Cassini-Huygens Analysis and Results of the Mission (CHARM) teleconference for professional science communicators and educators was held today. The topic: Dunes on Titan. CHARM is a monthly teleconference where scientists present recent science findings from the Cassini-Huygens mission. Presentation packages are available for all previous telecons. Audio recordings are also made available and posted as soon as their companion transcripts are complete. For access to previous presentations link to: http://saturn.jpl.nasa.gov/multimedia/products/CHARM.cfm An AACS Inertial Reference Unit (IRU) calibration was completed today on board the spacecraft. This incorporated the IRU-A scale factor updates that were uplinked recently with the A8.7.5 flight software (FSW) update. FSW normalization for AACS A8.7.5 is scheduled for March 4, 2007. An Encounter Strategy Meeting was held today for Titan flybys T26 and T27, and maneuvers numbered from 98-100. This covers the period from March 10 through March 26. Many Saturn Observation Campaign (SOC) members around the world continue to hold observation nights while Saturn is so well placed for viewing. March 3 offers a bonus! A full lunar eclipse in much of the world, and Saturn too! The eclipse will be visible from parts of all seven continents including the eastern half of North America. Contact your local SOC member for viewing opportunities in your locale. http://soc.jpl.nasa.gov/members.cfm Over the last several months, Cassini's orbit has climbed to higher and higher inclinations, providing never-before-seen views of Saturn from perspectives high above and below the planet's rings. An image release is available giving access to black and white and color mosaics, as well as a dramatic movie sequence showing the rings as they appeared to Cassini while it sped from south to north, rapidly crossing the ring plane. Beginning with Titan 26 on March 10, Cassini's highly inclined orbits around Saturn will be progressively lowered so that, by late June -- three years after entering orbit -- the spacecraft will once more be orbiting in the ring plane. Look for the new images and movies on the main page at: http://saturn.jpl.nasa.gov. Wrap up: 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.
