Cassini Significant Events 09/09/09 – 09/15/09

The most recent spacecraft telemetry was acquired on Sept. 15 from the Deep Space Network tracking complex at Goldstone, California. 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" page at: http://saturn.jpl.nasa.gov/operations/present-position.cfm

Wednesday, Sept. 9 (DOY 252):

The Spacecraft Operations Office (SCO) held an engineering activities review for the S59 sequence.

This week Imaging Science (ISS) took data for a lit face, high phase movie in search of ring spokes, and a mosaic of Iapetus. The Visual and Infrared Mapping Spectrometer (VIMS) observed the rings at phase angles of 110-130 degrees in an attempt to obtain spoke measurements, and ISS, the Composite Infrared Spectrometer, and the Ultraviolet Imaging Spectrograph performed several observations in the Titan monitoring campaign.

Next week, when the Superior Conjunction separation angle reaches two degrees, the spacecraft will remain on Earth point for five days until Sept. 19. As was mentioned in a previous report, Radio Science will be conducting a daily conjunction experiment from Sept. 6 through the entire conjunction period, ending on Oct. 2. During this time, the suite of Magnetospheric and Plasma Science instruments will be gathering as much science data as possible.

Thursday, Sept. 10 (DOY 253):

At the Mission Planning Forum today the team discussed a DSN station allocation straw man plan for the proposed Extended Extended Mission, covering what is contained in the plan and when that information will be propagated to the Cassini Information Management System. The second topic dealt with implementation of the Y-thruster biasing activities scheduled to begin with sequence S60.

Friday, Sept. 11 (DOY 254):

The Spacecraft and Uplink Operations teams sent commands to the spacecraft today to update onboard telemetry (TLM) modes for the Cassini Plasma Spectrometer (CAPS) and Cosmic Dust Analyzer instruments. Due to extensive and successful ground testing, it was decided not to perform a special TLM mode cycling test onboard the spacecraft. The TLM mode change at the end of today's track provided the first indication that the update was successful.

Today marked the official start of Superior Conjunction. During this time the angle between the sun and the spacecraft as seen from Earth gradually decreases until Sept. 17 when it will reach minimum separation just under two degrees this year. After the 17th, the angle begins to increase again with the conjunction period ending on Sept. 22 when separation reaches four degrees and rising. As is performed every year, beginning on Sept 15 and for the next 5 days, SCO will send a series of "empty" commands to the spacecraft to characterize interference from the Sun during conjunction.
With the expectation that this interference will be prohibitive to real time commanding, a command moratorium - except in case of emergency - has been declared for Sept. 15-19. Also with the expectation that a command loss timer (CLT) update would be unable to be received by the spacecraft, changes were put into the background sequence to update the onboard CLT value to 9 days on Sept. 12. This value will drop approximately one day per day until Sept. 20 when the timer is returned to the nominal 90-hour value.

Monday, Sept. 14 (DOY 257):

Scientists using the Cassini spacecraft's Magnetospheric Imaging instrument have detected a new, temporary radiation belt at Saturn, located around the orbit of its moon Dione at about 377,000 kilometers from the center of the planet. The instrument detected the new belt, which has been named "the Dione belt," for only a few weeks on three separate occasions in 2005. Scientists believe that newly formed charged particles in the Dione belt were gradually absorbed by Dione itself and another nearby moon, Tethys, which lies slightly closer to Saturn at an orbit of 295,000 kilometers. The discovery was presented at the European Planetary Science Congress in Potsdam, Germany on Sept. 14. See: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20090914/

Tuesday, Sept. 15 (DOY 258):

Saturn's Turbulent 'Storm Alley' Sets Another Record.

The longest continuously observed thunderstorm in the solar system has been roiling Saturn¬?s atmosphere since mid-January and is still churning now, according to a presentation by a Cassini team scientist at the European
Planetary Science Congress in Potsdam, Germany. For the complete story and images go to: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20090915/