NASA’s Cassini spacecraft will be flying within about 74 kilometers of Saturn’s moon Enceladus on May 2, aiming primarily to learn more about the moon’s internal structure. The flyby is the third part of a trilogy of flybys — the other two took place on April 28, 2010, and November 30, 2010 — for Cassini’s radio science experiment.
The radio science team is particularly interested in learning how mass is distributed under Enceladus’ south polar region, which features jets of water ice, water vapor and organic compounds spraying out of long fractures. A concentration of mass in that region could indicate subsurface liquid water or an intrusion of warmer-than-average ice that might explain the unusual plume activity.
Cassini’s scientists learn about the moon’s internal structure by measuring variations in the gravitational pull of Enceladus against the steady radio link to NASA’s Deep Space Network on Earth.
More information about the flyby is available on the NASA Jet Propulsion Laboratory website. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.