From: Jet Propulsion Laboratory
Posted: Thursday, July 17, 2014
Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 46.5 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on July 9 using one of the 34-meter diameter Deep Space Network stations at Canberra, Australia. 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"
The S84 command sequence continued to orchestrate all of Cassini's activities this week. Meanwhile on the ground, the Sequence Implementation Process teams worked on creating the 10-week sequences S85, S86, and S87. Planning continued for the 2016 start of the F-ring and Proximal Orbits mission phases which are now known as the Cassini Grand Finale.
Wednesday, July 2 (DOY 183)
Cassini reached apoapsis today, having climbed 2.98 million kilometers from Saturn while slowing to 8,745 kilometers per hour relative to the planet. The Imaging Science Subsystem (ISS), the Composite Infrared Spectrometer (CIRS), and the Visible and Infrared Mapping Spectrometer (VIMS) viewed Titan for 90 minutes as part of the Titan monitoring campaign. The planet-like moon (Saturn's largest, which was named for the Greek mythological race of giants) was 3.9 million kilometers away. When this observation was done, ISS turned the spacecraft so its telescopes could make a two-minute storm-watch observation on Saturn.
Imaging and other remote-sensing instrument data have revealed the size, shape, and therefore the volume of Titan. Radio Science experiments that measure the Doppler shift of the spacecraft's radio signal, due to the spacecraft speeding up and then slowing down as it flies past Titan, have investigated Titan's mass as well as the internal distribution of its mass. Taken together, these data allow scientific deductions about the object's density and interior makeup. Today, a news feature describes some surprising findings related to these measurements:
Thursday, July 3 (DOY 184)
ISS, CIRS and VIMS made another observation in the Titan monitoring campaign, after which ISS spent two minutes watching storms. CIRS then executed a 10.5 hour observation of Saturn to better understand its composition. ISS and VIMS rode along. This was followed by another two-minute ISS storm watch.
Friday, July 4 (DOY 185)
Making use of its great distance from Saturn near apoapsis, the Cosmic Dust Analyzer (CDA) spent 14.5 hours observing dust that orbits Saturn in a retrograde direction. The S84 sequence then entered a planned pause, during which an Orbit Trim Maneuver (OTM) could be commanded from Earth in real time to target for the Titan T-103 encounter coming up on July 20. This opportunity was not used, however, because the Navigation team had determined that the spacecraft was very close to its expected path, and OTM-384 was cancelled.
Saturday, July 5 (DOY 186)
CDA spent 15 hours observing retrograde dust. The observation was repeated on Tuesday, though for two hours shorter than today's observation.
Sunday, July 6 (DOY 187)
ISS took images of a faint ring arc for 19 hours while it was sunlit at low phase angles. CIRS also acquired ring data.
Monday, July 7 (DOY 188)
ISS controlled the spacecraft's pointing for another 24 hours, this time to study the small irregular moon Kiviuq, a dark object in a highly inclined orbit about 11.1 million kilometers out. Kiviuq was named after a hero in Inuit mythology.
By flying in orbits that are not always in Saturn's equatorial plane, Cassini's remote-sensing instruments can view features located at high latitudes. The atmosphere's enigmatic hexagon and the hurricane-like vortex centered on the planet's north pole stand out in an image featured today: http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=5057
Tuesday, July 8 (DOY 189)
The Deep Space Network carried out two-way digital communications and radiometric tracking with Cassini on six occasions this week, using stations located in California and Australia.
Visit the JPL Cassini home page for more information about the Cassini Project: http://saturn.jpl.nasa.gov/
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