News | October 11, 2009
Titan Flyby (T-62) - Oct. 12, 2009
T-62: Studying Titan's Atmosphere and Retuning to the Plane
On Oct. 12, Cassini flew by Titan at an altitude of 1,300 kilometers and a speed of 6 kilometers per second. Closest approach for T-62 occurred at 3:02 AM PDT, latitude 64 degrees S. This flyby marked Cassini's return to more nearly equatorial orbits, setting up the spacecraft for future close encounters with icy moons.
For T-62, the Ultraviolet Imaging Spectrograph (UVIS) performed a self-calibrating solar occultation observation; the information came from a ratio of signal during occultation to signal of the unocculted sun or star just before and after occultation.
Solar occultations by Titan are the most valuable Titan observations for UVIS. They provide detailed vertical profiles of N, N2, and some hydrocarbons to more than 3000 kilometer altitude. Solar occultation measurements give a measure of the density profile of the main constituents of the atmosphere, and the rate of change of the N2 density with altitude gives information on the temperature.
UVIS also conducted Extreme Ultraviolet and Far Ultraviolet observations during this flyby. These observations give information on airglow, hydrocarbon absorptions, haze and optical properties globally, but with lower vertical resolution
The Visual and Infrared Mapping Spectrometer (VIMS) observed the formation, evolution, and decay of clouds, particularly mid-latitude and equatorial clouds. In ride-along mode, a solar occultation provided information on the vertical structure and composition of Titan's atmosphere and haze layer.
VIMS also obtained a global map of the western region of Senkyo.
CIRS carried out far-infrared limb sounding at 70 and 75 degrees latitude South to collect information on the atmospheric temperature, aerosols, and composition. ISS acquired a full-disk mosaic of western Senkyo at low phase angles, and rode along with VIMS to monitor clouds.
T-62 was a south polar, post-dusk flyby. Magnetometer (MAG) measurements provided a description of the draping and the pileup of the external magnetic field around Titan near the terminator. This will be a good complement to the data set acquired at T52-T61 and be used to characterize the background field for a similar local time with respect to Saturn and different SKR longitudes.
Radio and Plasma Wave Science (RPWS) measured thermal plasmas in Titan's ionosphere and surrounding environment; searched for lightning in Titan's atmosphere, and investigated the interaction of Titan with Saturn's magnetosphere.