Surface eruption on Enceladus, Saturn in the background….Credit : NASA/JPL
About this time last year the American space agency NASA reported on new data from the Cassini mission to the planet Saturn confirming that one of Saturn’s moons, Enceladus, has liquid water and probably an ocean. [SciTechStory post: Enceladus has at least a sea, possibly life] New data from another Cassini fly-by of Enceladus and reported in the Journal of Geophysical Research 4 March 2011, High heat flow from Enceladus’ south polar region measured using 10–600 cm?1 Cassini/CIRS data indicates that the south polar region of Enceladus generates far more heat than expected.
The key to the heat is stress or more geophysically speaking the tidal push and pull Enceladus experiences from the enormous gravity of Saturn and the tug of another moon, Dione. As Enceladus orbits Saturn it passes relatively close to Dione in a cyclical, possibly even seasonal pattern. This causes the material in the mantle and core of Enceladus to flex, which produces heat. The astrogeologists expected some heat. They’ve known since the early days of Cassini that Enceladus ejects enormous plumes of ice particles and water vapor from an area near the South Pole called the “tiger stripes.” These eruptions were probably the work of heating below the surface ice. However, the data from Cassini’s infrared spectrometer indicates an order of magnitude more heat than expected.
In numbers, it means they were expecting around 1.4 gigawatts of heating – they found 15.8 gigawatts. That’s about 2.6 times the amount of heat generated by the Yellowstone supervolcanic region, or 20 coal-fueled power stations. Certainly it’s enough heat to keep a relatively large body of water from freezing. Of course, any time astrobiologists find liquid water – especially heated water – visions of life dance in their heads.
Extrapolating from environments on Earth, the combination of liquid water, a heat source, abundant non-organic minerals and components of organic chemistry (all of which appear to exist on Enceladus) has led to the creation of life. Of course, with Enceladus this is still speculation – very tantalizing speculation.