> Cassini Significant Events for 02/07/07 - 02/13/07 The most recent spacecraft telemetry was acquired Tuesday, February 13, from the Goldstone tracking complexes. 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 . Wednesday, February 7 (DOY 038): Orbit Trim Maneuver (OTM) #93 was performed today. This is the apoapsis maneuver setting up for the Titan 25 encounter on Feb. 22. The main engine burn began at 1:45 AM PST. Telemetry immediately after the maneuver showed the burn duration was 1.52 seconds, giving a delta-V of 0.26 m/s. On January 26, OTM-91 was reported as the smallest reaction control subsystem maneuver to date. Well, not to be out done, OTM-93 is now the smallest main engine maneuver to date. The previous record holder was OTM-25, with a burn of 2.1 seconds and a delta-V of 0.34 m/sec. All subsystems reported nominal performance after the maneuver. Images of five small satellites, Prometheus, Atlas, Pandora, Dione, and Janus, were taken today with the goal of improving knowledge of their orbits. The majority of today was spent alternating back and forth between additional Saturn high latitude Visual and Infrared Mapping Spectrometer (VIMS) photopolarimetry and Ultraviolet Imaging Spectrograph (UVIS) auroral observations. This is part of the Hubble Space Telescope/Cassini International Heliophysical Year campaign. Both Hubble and Cassini have previously imaged Saturn's auroras, demonstrating that they vary in latitudinal position and extent and that they alter rapidly as conditions in the solar wind change due to activity on the Sun. Repeated observations today will help to understand how the auroras respond to the solar wind. Inferences can also be made about the upper atmosphere of Saturn and its interaction with the magnetic field. The Cassini Deputy Program Scientist gave an in-reach talk today to members of the flight team. Every quarter, Cassini gives a presentation on project status to NASA personnel. One part of that presentation includes the most significant science results from the previous three months. Over the last year, the flight team has requested that this presentation also be given internally to project members. A beautiful RADAR image of the liquid methane lakes on Titan is Astronomy Picture of the Day today. A delivery coordination meeting was held today for the Cassini Information Management System version 3.3.2. This update supports Oracle 10G and contains modifications to the Resource Checker process. Thursday, February 8 (DOY 039): An encounter strategy meeting was held today for the Titan 25 and Titan 26 flybys. The meeting will cover the period from Feb. 22 through March 19, and Orbit Trim Maneuvers 95-97. The kickoff meeting for the Hyperion live update was held today. The update will execute over DOY 046-047. Teams have been reporting the need for this update so the Go/No-Go meeting scheduled for tomorrow has been cancelled. It's a Go. Friday, February 9 (DOY 040): The Navigation team released an update of the prime mission reference trajectory to the Project today. The two main purposes for this update to the trajectory are to raise the Titan-32 periapsis altitude from 950 km to 975 km, and to change the September Iapetus encounter B-plane angle from 156.7 to 176.4 deg to improving the viewing geometry over the equatorial ridge. A delivery coordination meeting was held today for the Spacecraft Operations Office Inertial Vector Propagation tool (IVP) V12.1. The IVP tool is a ground software program for the Cassini attitude control and science teams, providing precision vector propagation for desired scientific and engineering targets. The first worldwide Saturn Observation Night was held Feb 10, 2007. Members of the Saturn Observation Campaign around the world aimed telescopes at Saturn, or gathered students in classrooms for Saturn art and science activities. Newspaper articles, web blogs, reports, pictures and stories are coming in to Cassini Outreach this week. So far reports are in from 75 individuals in 13 states and 13 countries, with many more reports of past events and plans for future events expected. Go to: http://saturn.jpl.nasa.gov/news/features/feature20070207.cfm for a NASA News Feature on the event. To find out where other Saturn viewing events are occurring in the next months, check: http://soc.jpl.nasa.gov/experience/gallery-archive-stories.cfm Sunday, February 11 (DOY 042): An AACS friction test of reaction wheels number 1, 2, and 4 was executed on board the spacecraft today. This test is performed every three months. The wheels are spun up to 900 rpm in both directions and are timed as they run down to zero. Compared to the last test on Nov. 15, 2006, RWA-1 showed a slight improvement in the clockwise direction and degradation in the counter-clockwise direction. RWA-2 was only slightly worse in the clockwise direction and unchanged in the counter clockwise direction. RWA-4 improved slightly in the clockwise direction and was unchanged in the counter-clockwise direction. Monday, February 12 (DOY 043): Cassini Outreach chaired a panel at the 2007 Space Technology and Applications International Forum (STAIF) conference this week, and participated on a plenary panel for STAIF in Albuquerque, New Mexico along with the NASA Associate Administrator for Education, the Director of Los Alamos National Laboratory, and the Director of Sandia National Laboratories. The topic was "Inspiring the Next Generation." Tuesday, February 13 (DOY 044): A final approval meeting was held today for the S28 background sequence. The sequence was approved and uplink has begun of the Instrument Expanded Block files to support the sequence. All uplinks will be complete by Friday, Feb. 16, and the sequence begins execution early Saturday morning, Feb. 17. Eclipse entry was the first of several upcoming observations of Iapetus. This instance is unique because the satellite enters eclipse through the shadow of the rings, but departs tomorrow from behind Saturn. The Composite Infrared Spectrometer (CIRS) was the prime instrument measuring heating and cooling caused by the solar eclipse to provide information on surface thermal inertia. VIMS provided supporting measurements of the bolometric Bond albedo, i.e. the fraction of the total incident radiation energy that is reflected, and the Imaging Science Subsystem provided supporting imagery. 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.
