Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 44.6 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on September 2 using one of the 34 meter-diameter Deep Space Network (DSN) stations at Goldstone, California. The spacecraft continues to be in an excellent state of health with all of its subsystems operating normally except for the instrument issues described at http://saturn.jpl.nasa.gov/news/significantevents/anomalies. Information on the present position of the Cassini spacecraft may be found on "Eyes on the Solar System."
This week, Cassini's sequence implementation teams worked on developing the ten-week spacecraft command sequences S86, S87, and S88; the "S" stands for "Saturn tour." In flight, the S85 sequence controlled the spacecraft while it coasted "up" away from Saturn, slowing towards an apoapsis on Sept. 4. As it normally does, the on-board attitude control system rotated the spacecraft about its three axes using the electrically driven reaction wheels, pointing the instruments for their scheduled observations. The Navigation team iterated solutions of Cassini's orbit using precise tracking measurements from the Deep Space Network and worked on plans for the next propulsive maneuver, which will be carried out on Sept. 7 while still in the vicinity of apoapsis.
Wednesday, Aug. 27 (DOY 239)
The Ultraviolet Imaging Spectrograph (UVIS) controlled spacecraft pointing for 16 hours today to create a map of Saturn's atmosphere in the extreme- and far-ultraviolet parts of the reflected sunlight's spectrum. The Composite Infrared Spectrometer (CIRS) and the Imaging Science Subsystem (ISS) made observations in ride-along mode while UVIS called the shots.
Thursday, Aug. 28 (DOY 240)
CIRS made an observation lasting 22 hours, creating a map of Saturn's atmosphere in the mid-infrared. The Visible and Infrared Mapping Spectrometer (VIMS) rode along, making its own observations while CIRS controlled the pointing.
Friday, Aug. 29 (DOY 241)
CIRS stared at one spot on Saturn for 7.5 hours today, gathering data on the atmosphere's composition. UVIS and VIMS rode along, taking data as well.
Saturday, Aug. 30 (DOY 242)
ISS started a long observation of Saturn's very dark-surfaced, irregular moon Thrymr. This cold object was aptly named after a frost giant in Norse mythology. It has a diameter of about six kilometers, and orbits Saturn in a retrograde, inclined path more than twenty-million kilometers out from the planet. ISS's observation lasted over 37 hours.
Sunday, Aug. 31 (DOY 243)
The S85 command sequence, which is controlling Cassini's actions over a 10-week span, consisted of too many commands to entirely fit in the spacecraft's memory, so it was divided into two parts. The first part, which was uplinked via the DSN on July 26, finished executing today. The second part, uplinked on Aug. 26, began clocking out today. It will control the distant robot until Oct. 5, at which time the S86 sequence, still being created, will take over.
Monday, Sept. 1 (DOY 244)
VIMS began a 36-hour observation of Saturn to make a movie of its northern hemisphere. CIRS and ISS rode along.
Tuesday, Sept. 2 (DOY 245)
This week, the DSN communicated with and tracked Cassini on five routine occasions, using stations in Australia and California. A total of eight individual commands were uplinked, and about 980 megabytes of telemetry data were downlinked at rates as high as 142,201 bits per second.
Cassini participated in another Project Interface Test of the newly constructed 34 meter-diameter station in Australia, validating the station's command system, along with its previously exercised telemetry, tracking, and radio science data systems.