Cassini Significant Events for 02/16/06 - 02/22/06 The most recent spacecraft telemetry was acquired Wednesday, February 22, 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 . Thursday, February 16 (DOY 047): The passive microwave radiometer of Cassini's RADAR instrument collected distant Titan data for radiometer science and calibration from a distance of 2.4 million km. Operating at 13.78 GHz, the radiometer measured brightness and polarization of Titan's microwave emission. This information will contribute to the science goal of determining surface properties such as temperature, composition, and roughness. Friday, February 17 (DOY 048): The S21 Science Operations Plan Update process began today. The kick-off meeting will occur Tuesday, February 21. The process will run for 5 weeks and conclude on March 24. Saturn Observation Campaign members held events this month in: San Francisco and Martinez, CA Plano, Crowell, Dallas, Fort Worth, San Antonio and Corsicana, Texas New Port Richey and Orlando, Florida Gilbert, Arizona Ann Arbor, Michigan Steilacoom, Washington Paragould, Arkansas Broomfield, Colorado Devens, Massachusetts. International events were also held in Germany and Portugal, reaching over 3,000 attendees. Cascade, Wisconsin will try again Feb 24th, after a weather cancellation earlier in the month. Monday, February 20 (DOY 051): The sequence leads for S18 uplinked commands to update a RADAR trigger, and three Radio and Plasma Wave Science (RPWS) triggers. All are registered and active on-board the spacecraft. The commands will execute on Saturday prior to next week's Titan flyby. Radio Science (RSS) performed Ultra Stable Oscillator characterization and periodic instrument maintenance activities today. In addition, RSS team members supported an operations readiness test for Titan gravity science. Tuesday, February 21 (DOY 052): Cassini Outreach showed views of Saturn and its moons Titan, Iapetus, Rhea, Tethys and Dione to over 100 students and parents at the Santa Fe Middle School, Monrovia, CA annual Parent Teacher Association Founders Day celebration. Wednesday, February 22 (DOY 053): The first-ever picture of Saturn's moon Telesto is Astronomy Picture of the Day today. The Monopropellant Tank Assembly (MTA) Recharge Activity Project Review was held this afternoon. The MTA recharge will be performed during S19 on April 10, 2006. This activity brings the thrust up to the required level for ACS to provide control authority for the planned lower altitude Titan flybys, starting with T-16 at 950 km on July 22, 2006. Right after the recharge, ACS will upload a flight software patch to bring the default thruster magnitudes in line with the expected values. As mentioned in previous weeks, the project has been working on adopting a new reference trajectory in order to raise the minimum Titan flyby altitude for various encounters. Today the project reached a decision to proceed with the "optocc2" trajectory. Additional work is still to be performed before delivery of the final files. This will include minor tweaks that have been analyzed in other trajectories, adjusting orbit 68 timing, and capture of an Enceladus plume occultation on orbit 28. The new trajectory provides a small net savings in delta-V with respect to the current reference trajectory. Final review and details will be worked out between now and the end of the week. Significant effort was put into analysis of multiple trajectory options over the last several weeks. Mission Planning wishes to recognize and thank those individuals who supported this effort. Orbit Trim Maneuver (OTM) 52, scheduled for execution on February 23, has been cancelled. The decision was reached after the orbit determination solution using one more day of data moved the Titan flyby estimate by about one kilometer. This is well within the expected variations and science has not identified a requirement to execute the OTM. A Reaction Wheel Assembly bias, normally included in the OTM file, will be uplinked separately this evening, and will execute on DOY 055. UPCOMING EVENTS: The public is invited to attend a dark sky stargazing and Saturn gazing event at the Southern California Joshua Tree National Park, Hidden Valley Picnic Area, on Saturday, February 25, beginning at 5:30 p.m. Pacific Time. Contact Cassini Outreach staffer Jane H. Jones at for directions. A combined Saturn Observation Campaign (SOC) /International Occultation Timing Association (IOTA) event will be held Friday March 3, in Pleasant Hill, California at 6:30 PM Pacific Time. IOTA is an organization whose members study, record, and report stellar occultations. At this event, participants will be able to observe a magnitude 6.8 star blink off and on as it passes behind the mountains of the Moon's South Pole. This is a great opportunity to learn about both programs as you view the occultation event via TV video/telescope hookup. SOC will be setting up equipment and telescopes at the Sun Valley Mall at the corner of Contra Costa Blvd and Willow Pass Rd in Concord, California. 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.
