From: Jet Propulsion Laboratory
Posted: Tuesday, October 7, 2014
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 17 using the Deep Space Network (DSN).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":
Scientists who attended last week's European Planetary Science Congress (EPSC in Estoril, Portugal), report an exciting two days of talks under the theme of "Celebrating 10 years of exploration with Cassini-Huygens." Thirty-four scientists made presentations and displayed 29 posters which highlighted instrument-team contributions and Saturn-system science. Other Cassini-related sessions throughout the week included talks and posters on giant planets, planetary rings, Titan's surface and interior, and planetary magnetospheres.
Wednesday, Sept. 10 (DOY 253)
Cassini turned its telescopes toward Saturn's largest moon Titan for 90 minutes to allow the Imaging Science Subsystem (ISS), the Composite Infrared Spectrometer (CIRS) and the Visible and Infrared Mapping Spectrometer (VIMS) to make a cloud monitoring observation from a distance of 2.1 million kilometers. Next, ISS led CIRS, VIMS, and the Ultraviolet Imaging Spectrograph (UVIS) in a 26.5-hour observation of Saturn's northern polar vortex. Data from these observations will be stitched into in a movie of this enigmatic feature.
Thursday, Sept. 11 (DOY 254)
The round-trip communications time, as microwave radio signals propagate from the DSN on Earth to Cassini and back again, is 2 hours 52 minutes today. This is increasing by a few seconds each day as Earth continues to swing around the Sun away from Saturn. For comparison, the time needed for radio communications to travel the distance to Earth's Moon and back is around three seconds.
Friday, Sept. 12 (DOY 255)
ISS led CIRS and VIMS in another 90-minute Titan cloud monitoring observation, this time from 1.6 million kilometers away. UVIS then turned to Saturn to spend 16 hours examining it in the extreme-and far-ultraviolet (EUV and FUV) ranges of energies. ISS made observations in ride-along mode. Next, VIMS controlled pointing for nine hours to look at Saturn's north polar auroral region, with ISS and UVIS riding along.
Saturday, Sept. 13 (DOY 256)
UVIS assumed control of the spacecraft's attitude to watch the same area on Saturn for another nine hours.
Sunday, Sept. 14 (DOY 257)
ISS and VIMS spent 90 minutes on another Titan cloud monitoring observation from 1.4 million kilometers away. VIMS then took over to point to Saturn, beginning a 34.5-hour-long observation of the northern hemisphere to create a movie covering three full rotations of the gas giant. CIRS and ISS rode along.
Tonight, Cassini's Saturn Observation Campaign volunteer in Iraqi Kurdistan organized regional Saturn viewing events there along with similar events in Jordan, the Arabic Republic of Syria, Oman, Tunisia, Jordan, and Saudi Arabia. The 10 events drew more than 500 participants, despite cloudy skies in Saudi Arabia. Saturn is low on the western horizon this month, but will be easy for anyone to spot near the moon on Sept. 27. See
Monday, Sept. 15 (DOY 258)
A realtime commanding procedure began today which will manage copies of the CIRS flight software that reside on the spacecraft. The new version has been proving itself with many CIRS in-flight observations, so when the procedure finishes next week the new version will be marked prime (with equivalent backup copies also on board) and the old one discarded. Saturn's moons have extremely diverse surfaces and characteristics. A crescent image of Mimas featured today shows off its many impact craters in clear relief:
Tuesday, Sept. 16 (DOY 259)
ISS led another Titan cloud monitoring observation with CIRS and VIMS riding along; this time their moving target was 1.5 million kilometers away. Finishing off the week, all of Cassini's telescopes then turned to Saturn; UVIS spent nine hours collecting EUV and FUV spectral data while ISS and CIRS rode along to observe the visible and infrared light. Finally, ISS took over pointing, still on Saturn, to spend nearly eight hours mapping the northern hemisphere while CIRS and VIMS rode along.
Today, sequence implementation work began with a "kick-off meeting" for the ten-week command sequence S88, which will control the spacecraft starting in February 2015. Previously negotiated science activities, such as target observations, will be integrated with engineering activities, such as reaction wheel bias maneuvers and orbit trim maneuvers. Negotiations to schedule the needed DSN antennas and telemetry systems are proceeding. All the activities will be translated into a thoroughly validated file containing thousands of individually timed commands, to uplink to the flight system a few days before they take control.
This week, the DSN communicated with and tracked Cassini on four occasions, using stations in California. A total of 24 individual commands were uplinked, and about 1,050 megabytes of telemetry data were downlinked at rates as high as 142,201 bits per second. Nine hours of Radio Science data were collected for calibration. A small amount of the DSN time scheduled for Cassini this week was released to the Dawn project to help in their recovery activities.
For a glossary of technical terms relating to these events, click the "full story" link on this page:
Visit the JPL Cassini home page for more information about the Cassini Project:
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