The existence of ample amounts of hydrogen in the subsurface ocean of Enceladus indicates that microbes--if any exist there--could use it to obtain energy by mixing with carbon dioxide dissolved in water. This particular chemical reaction, termed methanogenesis, because it manufactures methane as a byproduct, may have been of critical importance in the emergence of life on our planet.
A Moon Made Of Lightweight Fluff! Methone is small and oval--and unlike other tiny objects, composed of rock and ice, that scurry around our Solar System. Methone, which was observed up close for the very first time in 2012, is not pockmarked by impacts like other worldlets of its kind. Instead, this strange little moon, is very smooth--it shows not a hill nor an impact crater anywhere on its weirdly smooth surface. This shiny, white, icy egg in Space, residing in a peaceful nest of ice crystals, is an enigma wrapped in a bewildering mystery that some astronomers may have solved. The answer to the bewitching riddle of Methone? It is composed of lightweight fluff!
But small moons like Methone are usually geologically inactive and bereft of an atmosphere. Therefore, they are usually unable to smooth away the scars. Dr. Peter Thomas of Cornell University in Ithaca, New York, explained it this way in the May 17, 2013 New Scientist: "When we look at objects less than 200 kilometers in radius, they are all like potatoes. They have lumps, grooves, craters." This makes Methone's smooth surface a mystery. Dr. Thomas is a Cassini team member.