From: Jet Propulsion Laboratory
Posted: Monday, August 4, 2014
Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 48 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on July 29 using the 70-meter diameter Deep Space Network station 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":
Sequence Implementation Teams worked on developing the ten-week command sequences S86 and S87, and on scheduling some S88 implementation activities. Mission planners continued to work on the 2016-2017 Cassini Grand Finale phase, which is described here:
Wednesday, July 23 (DOY 204)
The Cosmic Dust Analyzer (CDA) spent 14.5 hours observing dust that orbits Saturn in the retrograde direction. The S84 command sequence, which is controlling the spacecraft, then took a planned break in on-board activities to allow an Orbit Trim Maneuver (OTM) to be commanded in real time. But the Cassini Navigation team had determined that the Titan T-103 flyby on July 20 was so close to its target (within about 200 meters) that the trajectory-cleanup OTM was not needed. Therefore, work to prepare and execute OTM 386 today was cancelled.
Thursday, July 24 (DOY 205)
CDA carried out another retrograde dust observation. This one lasted 15 hours.
Friday, July 25 (DOY 206)
The Imaging Science Subsystem (ISS) performed an observation in the satellite orbit campaign, looking at objects orbiting near the planet, after which it turned to carry out a two-minute storm-watch observation on Saturn. Next the Visible and Infrared Mapping Spectrometer (VIMS) created a mosaic of the sunlit side of the rings while ISS, the Ultraviolet Imaging Spectrograph (UVIS), and the Composite Infrared Spectrometer (CIRS) acquired data in ride-along mode. When that was completed, VIMS led an observation with ISS and CIRS riding while the red star L2 Puppis passed behind the rings. The occultation lasted 6.75 hours. Then ISS did another storm watch; these two-minute observations of Saturn were repeated twice on Sunday and once again on Monday. Late in the day, ISS started a four-hour color scan of the sunlit face of the main rings, with CIRS and VIMS riding along.
Saturday, July 26 (DOY 207)
The Navigation team used ISS to take images of Saturn's satellite Tethys against background stars for optical navigation purposes. ISS then turned its telescopes toward Saturn's irregular moon Ijiraq. This very dark moon has a diameter of about 10 kilometers, orbits about 11 million kilometers out from Saturn, and was named for a creature in Inuit mythology that plays hide-and-seek. Images were acquired for about 13 hours. Later in the day, Cassini trained its high-gain antenna toward Earth just in time to begin receiving a navigation reference signal uplinked from the 70 meter-diameter Deep Space Network (DSN) station at Goldstone, California. Shortly thereafter, all 6,674 individual commands comprising the first part of the S85 command sequence streamed aboard the spacecraft and were stored properly; they are ready to begin controlling the flight system's activities on July 31, when S84's ten-week execution ends.
Sunday, July 27 (DOY 208)
CIRS stared at the sunlit side of the rings to obtain spectra in the thermal infrared region for a study of ring particle composition. CIRS then began a 10-hour Saturn observation to better define its composition, with VIMS riding along.
Monday, July 28 (DOY 209)
ISS observed Ijiraq for another 14 hours. The tiny, but geologically active Saturnian moon Enceladus continues to make headlines:
This view of Tethys which was released today does not show background stars, as do optical navigation images, because camera settings were selected for remote-sensing of the object's surface rather than its position:
Tuesday, July 29 (DOY 210)
UVIS began its yearly campaign to study Saturn's magnetosphere with a 38-hour mosaic scan. Scans like this one focus on the vicinity of Saturn to detect oxygen.
This week, the DSN communicated with and tracked Cassini on four occasions, all from Goldstone, California. A total of eight individual commands, in addition to the 6,674 of the S85 sequence, were uplinked this week. About 1,260 megabytes of telemetry were downlinked at rates as high as 142,201 bits per second. Also this week, coherent Doppler-shift data and ranging data were obtained for a total of about 24 hours, and nine hours of Radio Science data were collected for system calibration.
Visit the JPL Cassini home page for more information about the Cassini Project: http://saturn.jpl.nasa.gov/
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