From: Jet Propulsion Laboratory
Posted: Monday, October 28, 2013
Cassini is orbiting Saturn with a 47.9-day period in a plane inclined 49.7 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on Oct. 22 using the 70-meter diameter Deep Space Network station at Goldstone, California. Except for the science instrument issues described in previous reports (for more information search the Cassini website for CAPS and USO), the spacecraft continues to be in an excellent state of health with all of its subsystems operating normally. Information on the present position of the Cassini spacecraft may be found on the "Present Position" page at:
The S81 sequence was uplinked, and the final S80 commands controlling Cassini were executed this week. Meanwhile, work proceeded at JPL on the ten-week command sequences S82 and S83. Planning also continued for the 2016 start of the F-ring and Proximal Orbits phase; the latter will fly the spacecraft in between the innermost D ring and Saturn's upper atmosphere before ending the mission with Saturn entry.
Wednesday, Oct. 16 (DOY 289)
Following Monday's T-95 close encounter, the Imaging Science Subsystem (ISS) continued monitoring Titan to track clouds and their evolution in the high southern latitudes where winter is approaching. The Composite Infrared Spectrometer (CIRS) and the Visible and Infrared Mapping Spectrometer (VIMS) took data as well. VIMS then observed an ingress occultation of the red star R Lyrae as it passed behind the rings going from the F Ring to the D Ring. ISS took advantage of this pointing and took data as well, primarily to observe the F ring.
Thursday, Oct. 17 (DOY 290)
After two days of radiometric tracking by Deep Space Network (DSN) stations on three continents, the Navigation team determined that Orbit Trim Maneuver (OTM)-362, the post-T-95 trajectory cleanup planned for today, was unnecessary since the flyby was so accurate. The propulsive maneuver was cancelled. CIRS began a fifteen-hour observation to create a temperature map of Saturn's south polar region.
Some of the data that VIMS obtained on July 19 while Cassini was behind Saturn show the planet's night side glowing brightly in the infrared. The backlit rings also provide spectral clues to help reveal their properties, as seen in an image featured today:
Friday, Oct. 18 (DOY 291)
The Realtime Operations team used the 70-meter diameter DSN station in Spain to uplink a file of 7,713 individually timed commands comprising the S81 sequence, which will begin its ten-week execution next Wednesday. After a round-trip light time of three hours, telemetry showed that all the commands were properly received and registered aboard. ISS then turned the spacecraft off Earth-point and led the creation of a sixteen-hour low-resolution movie of the narrow, ever-changing F ring with CIRS and VIMS riding along.
Saturday, Oct. 19 (DOY 292)
ISS performed an observation in the satellite orbit campaign, looking for small bodies orbiting near Saturn. It then led an observation to search for periodicities of the ring spokes with CIRS and the Ultraviolet Imaging Spectrograph (UVIS) also taking data. More information on ring spokes may be found here:
Following the satellite orbit observation, the Navigation team used ISS to take images of Saturn's satellite Tethys against the field of stars for optical navigation purposes.
Sunday, Oct. 20 (DOY 293)
VIMS, CIRS, and UVIS spent twelve hours making a mosaic of the dark side of the rings, then ISS, CIRS, and VIMS performed another Titan monitoring campaign observation, this one from a distance of 1.7 million kilometers.
Monday, Oct. 21 (DOY 294)
ISS created a twelve-hour medium-resolution movie of the D ring at high phase angle illumination. The fine particles in this tenuous innermost ring light up best in forward-scattered sunlight. Aside from the basic scientific value, this observation is also of interest to mission planners as they develop the Proximal Orbit phase of the mission. ISS, CIRS, and UVIS then began a twenty-four-hour ring movie again searching for spoke periodicities.
Amateur astrophotographer Gordan Ugarkovic composed this mosaic is from raw images from the Cassini website, which NASA has featured as today's Astronomy Picture of the Day: http://apod.nasa.gov/apod/ap131021.html . The Cassini website caption for this image may be viewed here:
The edges of some of Saturn's rings are defined by shepherding moons, which interact gravitationally with ring particles. Two such moons are seen at work on two different rings in an image released today:
Tuesday, Oct. 22 (DOY 295) The last of the commands stored onboard Cassini in the ten-week S80 sequence executed today. They turned the spacecraft to point its high-gain antenna dish to Earth, set telemetry rates, and managed a nine-hour playback from the solid-state recorder during a DSN pass; the highest data rate was 110,000 bits per second. This was one of five communication sessions via the DSN this week.
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