From: Jet Propulsion Laboratory
Posted: Tuesday, March 3, 2009
The most recent spacecraft telemetry was acquired on Feb. 24 from the Deep Space Network tracking complex at Goldstone, California. The Cassini spacecraft is in an excellent state of health. Information on the present position and speed of the Cassini spacecraft may be found on the "Present Position" page at: http://saturn.jpl.nasa.gov/operations/present-position.cfm.
Wednesday, Feb. 18 (DOY 049)
Spacecraft Operations hosted the S53 Engineering Activities Review today. At this review the team goes over all engineering and health and safety activities to be performed during sequence execution.
Thursday, Feb. 19 (DOY 050):
Sequence activities began with a series of Optical Navigation images collected by the Imaging Subsystem (ISS). These images of Saturnís satellites against the background stars allow the Navigation team to more accurately determine Cassiniís orbit. The day ended with a thirteen-hour observation of Saturnís E and G rings by the Visual and Infrared Mapping Spectrometer (VIMS).
Friday, Feb. 20 (DOY 051):
Work continued on preparations for the swap to the RCS thruster B-branch, scheduled to begin Mar. 12. A technical review of the Cassini Thruster Swap and Checkout Plan was held today. Representatives from Divisions 31, 34, and 35 participated.
A detailed review of the "Open LV-41 and swap to B-branch" procedure was also held today. The Integrated Test Laboratory dry run will be kicked off Feb. 23. Both the procedure and various contingency files will be tested that week.
An AACS friction test of the backup reaction wheel # 3 was performed today. In this test, performed every 6 months, the wheel is spun up to 600 rpm in both the clockwise and counterclockwise directions, and timed as it is allowed to run down to zero. Results were unchanged from previous tests.
Today the Ultraviolet Imaging Spectrograph (UVIS) oriented the spacecraft to target Enceladus for a three and a half hour observation designed to map the system in the immediate neighborhood of Enceladus. Observations tested the connection between volatile changes and plume eruptions. Next, ISS targeted a few more icy satellites in the Saturn system. The day ended with an experiment conducted by the RADAR instrument where, instead of actively bouncing RADAR signals off Titan, they passively measured the radio heat signature of Titan. This type of measurement is referred to as radiometry.
Science Planning handed off all files and materials to Uplink Operations to begin final sequence development for S50.
An after-school adaptation of Reading, Writing & Rings was presented to 60 Los Angeles area educators on February 19 and 20, 2009.
Educator-Astronaut Barbara Morgan will be the keynote speaker at the International Reading Association's Annual Convention West in Phoenix, AZ, February 21-25, 2009. She will feature "Reading, Writing & Rings" in her address. Cassini Outreach provided copies of the RWR CD-ROM to her to distribute to 300 teachers attending the conference.
Monday, Feb. 23 (DOY 054):
The Target Working Team (TWT)/ Orbiter Science Team (OST) integrated products for S53, covering orbits 117 through 119, were delivered today. The integrated products are in their final form and no re-integration is planned. The next step in sequence development, Science Operations Plan (SOP) implementation, will kick off on Mar. 9. Between now and then, the instrument teams will be working on pointing designs for the sequence. TWT/OST teams deliver integrated sequence products for the extended mission about every five weeks.
Tuesday, Feb. 24 (DOY 055):
Contingency planning is one of the many ongoing activities while a flight project is in the operations phase. A possible scenario might be that someday the reaction wheels on board Cassini may fail. That scenario and the options for conducting a thrusters-only mission was the topic of discussion at the Mission Planning Forum today. The presentation included Reaction Control Subsystem hydrazine budget with number of turns per day, different options for articulating the spacecraft at slower rates and accelerations, wider deadbands, etc.
The February Cassini-Huygens Analysis and Results of the Mission teleconference for the JPL outreach networks featured "Rings around a moon? The puzzling case of Rhea." The presentation can be downloaded from the Cassini website at: http://saturn.jpl.nasa.gov/video/products/MultimediaProductsCharm/
Each year dozens of Cassini scientists, engineers and educators volunteer to support Open House. In 2009, JPL open house takes place all day Saturday and Sunday, May 2 and 3. The attached link will take you to a Cassini specific video from 2008. There are additional videos on the page. http://www.jpl.nasa.gov/video/index.cfm?id=814
On Feb. 24, a quadruple transit of Saturn's moons occurred when Titan, Mimas, Dione and Enceladus passed directly in front of Saturn as seen from Earth. The Hubble Space Telescope and amateur astronomers from along the Pacific coast of North America, Alaska, Hawaii, Australia and East Asia were able to observe this event. Transits like these are rare. They only happen every 14 to 15 years when the orbits of Saturn's moons are nearly edge-on to Earth. For more information link to:
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