Cassini prepares for a final pass of icy Enceladus
NASA's Cassinispacecraft is preparing for its final flyby of the icy moonEnceladus. The pass is slated to take place on Dec. 19 at a distanceof 3,106 miles (4,999 km). This final close proximity encounter ofEnceladus comes as part of a farewell tour of Saturn's moons that havebeen so well characterized by the spacecraft, prior to beginning its"Grand Finale" mission late in 2016.
The Grand Finale willsee the venerated explorer perform a series of daring maneuvers,including repeatedly diving between Saturn's innermost ring and itssurface as it collects information on aspects of the gas giant, including ring mass and characterizing the ringed giant's magneticand gravitational fields.
Compared to theprevious 21 flybys of Enceladus, the closest of which took Cassini towithin 16 miles (25 km) of the moon's surface, the upcoming pass willbe relatively remote. This aspect of the pass is an intentional moveby Cassini's handlers, designed to maximize the capabilities of theprobe's Composite Infrared Spectrometer (CIRS) instrument.
During the pass, CIRSwill take detailed measurements of the heat flow passing acrossEnceladus' south polar region, emanating from the moon's interior.
"The distance ofthis flyby is in the sweet spot for us to map the heat coming fromwithin Enceladus – not too close, and not too far away" statesMike Flasar, team lead for CIRS at NASA's Goddard Space FlightCenter. "It allows us to map a good portionof the intriguing south polar region at good resolution."
The heat data couldpotentially grant insights into the fascinating geological mechanicstaking place beneath Enceladus' icy shell that work to power themoon's magnificent plumes of gas and ice.
The observations willbe carried out during the southern hemisphere's winter cycle. Thisperiod creates ideal conditions for carrying out the observations, asthe lack of sunlight makes it easier to detect and differentiate heatemanating from within the moon. It is expected at the end ofCassini's mission that the probe will have collected over six yearsworth of winter observations of the icy moon's southern hemisphere.