Jets of water ice particles, along with gases dominated by water vapor, spew out from the south polar region of Saturn's moon Enceladus in this dramatically illuminated image. Image taken Dec. 25, 2009.

Jets of water ice particles, along with gases dominated by water vapor, spew out from the south polar region of Saturn's moon Enceladus in this dramatically illuminated image. Image taken Dec. 25, 2009.

Enceladus 'E-12' Flyby: Insight into the Interior of Enceladus

The 'E-12' flyby (the 12th targeted Enceladus flyby) is the first in a pair of two flybys with very similar geometries – about 48 kilometers altitude over the northern hemisphere. The second flyby in the pair will occur next month. E-12 is grouped with two south-polar flybys, one that was executed on April 28 earlier this year and one that will occur in May 2012. The Cassini Radio Science Subsystem (RSS) will use this suite of flybys to carefully measure the gravity field of Enceladus and determine the nature of the interior - particularly under the intriguing south polar hot spot.

There will be two three-hour "wing" observations before and after closest-approach (from five to eight hours from closest approach on either side), and then three more hours centered directly around closest approach. Between RSS observations, the imaging science system (ISS) and composite infrared spectrometer (CIRS) will observe this moon on the inbound leg, and CIRS and the visible and infrared mapping spectrometer (VIMS) will take data on the outbound leg (with other optical remote sensing and fields, particles and waves instruments riding along).