The Cassini flyby of Enceladus on March 12 show tracks of heat running along giant fissures in the south polar region. As depicted in the graphic below, heat is radiating the length of the 150 km (95 mi) fractures. The chemistry of Enceladus heat radiationEnceladus resembles that of a comet, although it is definitely a moon, evidenced by the internally generated heat measured by the recent flyby.

The material encountered by Cassini coming up from the surface of Enceladus was much denser than expected, 20 times more so. Volatile gases, water vapor, carbon dioxide and carbon monoxide were components of the plumes Cassini flew through.

Temperatures measured along the fissures were at least minus 135 degrees Fahrenheit. This seems very cold to me but when one realizes how far from the Sun Enceladus is, its actually considered relatively warm. It’s 200 degrees Fahrenheit warmer than other places on Enceladus. Scientists believe these temperatures make it more likely there is water flowing beneath the surface of this moon of Saturn.

Observations indicate that four sources of heat send plumes jumping up from the surface. These individual plumes meet and come together, blending to form one large plume.  Future investigations will look at the sources of the individual plumes and the differences among the fissures.

Cassini was 30 miles from Enceladus at its closest approach during this flyby and 120 miles out when it flew through the plumes. The next flyby is planned for August.