News | December 4, 2013
Cassini Significant Events 11/27/2013 - 12/03/2013
Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 51.3 degrees from the planet's equatorial plane. The most recent spacecraft tracking, telemetry, and radio science data were obtained on Dec. 4 using one of the 34-meter diameter Deep Space Network (DSN) stations 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 http://1.usa.gov/193My41.
Flying by Titan on Sunday morning gave Cassini a gravity-assist boost of over 750 meters per second to modify the shape of its orbit in keeping with the planned Saturn tour. The spacecraft’s orbital inclination went up from 49.7 degrees to 51.3 degrees, and the period went from 47.9 days down to 31.9, thanks to Titan's ample orbital momentum and gravitation. The next Titan flyby, on Jan. 1, 2014, will start bringing the inclination of Cassini's orbit back down again; it will be near-equatorial in 2015. More information about the gravity-assist technique may be found here: http://www.jpl.nasa.gov/basics/bsf4-1.php#gravity
Wednesday, Nov. 27 (DOY 331)
Cassini's Navigation team used the Imaging Science Subsystem (ISS) to take images of Saturn's satellite Tethys for optical navigation purposes. The Visible and Infrared Mapping Spectrometer (VIMS) then had the spacecraft turn and start creating an 11-hour long movie of Saturn’s north polar region to further study atmospheric dynamics.
Commands to execute Orbit Trim Maneuver (OTM) 364, the Titan approach maneuver that had been designed based on the latest tracking data and uplinked yesterday, went active today. They turned the spacecraft to the proper attitude and fired its small rocket thrusters for eight seconds. This provided the nudge to effect a 13 millimeter-per-second change in velocity, fine-tuning the flight path for a precise encounter three days later. This OTM happened to be the smallest one Cassini has ever executed.
Thursday, Nov. 28 (DOY 332)
ISS performed an observation in the satellite orbit campaign, looking for small objects near Saturn. VIMS spent eleven hours creating a map of Saturn’s north polar region. ISS then reacquired and tracked the orbits of known propellers (http://go.usa.gov/YyGR) in Saturn’s rings.
Friday, Nov. 29 (DOY 333)
With the giant moon looming large, ISS monitored Titan's high northern latitudes to track clouds and their evolution. VIMS and the Composite Infrared Spectrometer (CIRS) rode along with ISS for cloud and temperature mapping. CIRS then made a four-hour observation of the rings' sunlit side.
Saturday, Nov. 30 (DOY 334)
Cassini's T96 targeted Titan encounter began. The T-96 web page has all the details: http://saturn.jpl.nasa.gov/mission/flybys/titan20131201
Sunday, Dec. 1 (DOY 335)
Closest approach to Titan occurred early today, and scientific observations continued as described on the T-96 web page. Later, the spacecraft turned to train its high-gain antenna on Earth. After half an hour, the 70-meter diameter Deep Space Network (DSN) station in Australia began to prepare for a nine-hour communications session. Then, just as Cassini's X-band (8 GHz) radio signal was completing its 90-minute interplanetary journey at the speed of light, the DSN station finished turning its 3000-ton dish to face Saturn. Capture of telemetry data from the T-96 observations, and radiometric tracking data for navigation, then proceeded flawlessly.
Monday, Dec. 2 (DOY 336)
A twenty-five day period of cross-disciplinary science began with VIMS observing Saturn for eleven hours to map its southern region. CIRS then observed the unlit side of Saturn’s rings, which is the side that is never visible from Earth, for four hours.
A vortex at Titan's south pole produces the highest clouds on this giant moon. They can be seen catching sunlight above Titan's night side in an image featured today: /resources/15926
Tuesday, Dec. 3 (DOY 337)
VIMS observed both the ingress and egress of the red star R Lyrae as it was occulted by Saturn’s rings. Finally, ISS reacquired and tracked the orbits of known propellers again.