From: Jet Propulsion Laboratory
Posted: Friday, February 7, 2014
Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 48.1 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on Feb. 5 using the 70-meter diameter Deep Space Network (DSN) 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 "Eyes on the Solar System" at
This week's highlight was Cassini's T-98 flyby of Titan on Feb. 2. The Cassini Radar was prime at closest approach looking for changes to the shoreline of Ontario Lacus. The T-98 page describes details of the encounter:
Wednesday, Jan. 29 (DOY 029)
The Cassini navigation team used the Imaging Science Subsystem (ISS) to take six "optical navigation" images of Pluto for the benefit of the New Horizons Mission, which will execute a fast flyby of the icy dwarf planet and its satellites one year from this July. ISS then performed an observation in the satellite orbit campaign, viewing small known objects near Saturn and looking to discover new ones. Finally, ISS, the Composite Infrared Spectrometer (CIRS) and the Visible and Infrared Mapping Spectrometer (VIMS) started a fifteen-hour observation of Saturn's F ring, enough time to capture a complete revolution of its particles about the planet.
Thursday, Jan. 30 (DOY 030)
The flight team prepared and uplinked commands to perform Orbit Trim Maneuver 370. Cassini turned and fired its small thrusters for 51 seconds to produce a change in velocity of 54 millimeters per second, refining the spacecraft's trajectory on approach to the T-98 encounter.
Friday, Jan. 31 (DOY 031)
The Ultraviolet Imaging Spectrograph (UVIS), CIRS, and VIMS observed Saturn's northern aurora for six hours. CIRS then took control of spacecraft pointing to observe the rings in the far-infrared for eight hours in an effort to better determine their composition. After these observations completed, Cassini turned to point its high-gain antenna to Earth.
After one hour 23 minutes, the DSN antenna trained its Goldstone, California 70-meter diameter dish on Saturn and locked its receivers onto Cassini's downlink signal. Telemetry from the spacecraft showed that the Magnetometer (MAG) instrument had become unresponsive due to an interruption in data communications with the MAG bus interface unit (BIU). This is a known idiosyncrasy of the instrument and was the twenty-third occurrence since launch. The flight team prepared commands to recycle the instrument's electrical power, and after a round-trip light time, MAG was seen back online and operating normally, well in time for the T-98 encounter.
Saturday, Feb. 1 (DOY 032)
ISS monitored Titan's high northern latitudes, tracking clouds and their evolution as summer approaches. VIMS rode along to map the lakes and seas near the pole, and to monitor cloud formation at high northern latitudes.
Sunday, Feb. 2 (DOY 033)
Cassini carried out all the planned observations during its T-98 encounter with Titan, as described on the web page mentioned above. The flyby also provided the gravity-assist needed to decrease the inclination of Cassini's orbital plane, bringing it down two degrees closer to Saturn's equatorial plane.
Monday, Feb. 3 (DOY 034)
Outbound from Titan, CIRS increased its temporal mapping coverage of Titan's stratospheric temperatures to monitor seasonal changes. VIMS rode along with CIRS and observed the evolution of the south polar vortex. In its path outbound from Titan, Cassini lined up in positions where it could catch a glimpse of sunlight if it were reflected off Titan's surface at 44 degrees north latitude and at 40 south latitude. Although liquid surfaces, which would provide a specular reflection, are not expected at these latitudes, VIMS observed the regions at five microns wavelength in the infrared, just in case Titan defies expectations. ISS rode along with CIRS to track clouds over Titan's southern hemisphere. A previously captured infrared specular reflection from Titan can be seen here:
An image was featured today that beautifully shows features in Saturn's atmosphere, including the enigmatic north-polar hexagon:
Tuesday, Feb. 4 (DOY 035)
CIRS carried out a four-hour thermal ring study in support of phase-latitude mapping, to help assimilate models of the rings' directional emissivity. This is important for evaluating whether particle spin or packing structure affects the emission. Into the observation 10 minutes, the spacecraft flew through periapsis of its orbit #201, coming within 980,000 kilometers of Saturn and going 27,392 kilometers per hour relative to the planet.
Finally, ISS began a two-hour observation to retarget known "propeller" features (http://go.usa.gov/YyGR), including the one named Bleriot. These observations are important for maintaining temporal resolution of the of the objects' orbital evolution.
Visit the JPL Cassini home page for more information about the Cassini Project: http://saturn.jpl.nasa.gov/
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