View Full Version : Theories on why Saturn's moon Mimas is inactive

2007-Nov-08, 01:35 AM
Enceladus sports ice geysers courtesy of it's eccentric orbit around Saturn, in which it is alternately squeezed--when nearer Saturn--and let go--when further away. The tidal flexing keeps it's innards hot through friction. So since Mimas has an even more eccentric orbit, it should be subjected to even more extreme tidal heating. Why isn't it?

2007-Nov-08, 02:30 AM
This article states: (http://www.sciencenews.org/articles/20060506/bob9.asp)

In March, at NASA's annual astrobiology meeting in Washington, D.C., Julie Castillo of NASA's JPL presented one of the models for that energy.
<p>The key to Enceladus, her team proposes, is that it has a relatively rocky, much larger core than the inactive Mimas does. Coalescing about 3 million years after the birth of the solar system, the rocky material began to undergo radioactive decay, which generates heat. Short-lived radioisotopes, such as aluminum-26, jump-started the heating. Once these isotopes decayed, long-lived ones, such as uranium and thorium, took over and produced enough heat to melt the core, the team suggests.

Factors include: Time of Capture, composition of the moon and core and the theory above.