[LINK] "Icy Saturn Moon Pumps Out 15.8 Gigawatts of Heat Power"

[rfmcdonald]

This interesting story, one I found via io9. Why does Saturn's ice moon Enceladus seem to have a subsurface water ocean when it shouldn't be producing enough energy to make one (yet does)?


CREDIT: NASA/JPL/SWRI/SSI

The south polar region of a frigid Saturn moon churns out far more heat than Yellowstone National Park, Earth's most famous geologic hotspot, a new study finds.

Using data from NASA's Cassini spacecraft, researchers have determined that the far southern reaches of the Saturn moon Enceladus produce about 15.8 gigawatts of heat-generated power. That's about 2.6 times the power output of all the hot springs in and around Yellowstone — and 10 times more than scientists had predicted, researchers said.

The new find is intriguing to scientists since it adds more evidence for the likelihood of a liquid-water ocean under Enceladus' icy shell. But it's puzzling as well — researchers aren't sure where all that heat is coming from. [Gallery: The Rings and Moons of Saturn]

"The mechanism capable of producing the much higher observed internal power remains a mystery and challenges the currently proposed models of long-term heat production," study lead author Carly Howett, of the Southwest Research Institute in Boulder, Colo., said in a NASA statement Monday (March 7).

Enceladus is Saturn's sixth-largest moon and has a frigid surface but an active, roiling interior — at least near its south pole. In that region, geothermal activity is centered on four roughly parallel trenches informally known as "tiger stripes."

These fissures — each about 80 miles long and 1.2 miles wide (130 by 2 kilometers) — eject great plumes of water vapor and other particles into space. Cassini first discovered the Enceladus ice geysers in 2005.

In the new study, researchers used Cassini's composite infrared spectrometer to study the surface temperatures in Enceladus' south polar region. They then used the observations to determine the area's heat output.

The 15.8 gigawatts of heat on Enceladus measured by Cassini is roughly equivalent to the output of 20 coal-fired power plants. This came as a surprise, since a previous study had predicted that the region should generate only about 1.1 gigawatts, with Enceladus' own natural radioactivity adding another 0.3 gigawatts to that mix, researchers said.

I've a certain appreciation for commenter Billy Brantingham's suggestion: "Somewhere, under a sky of ice, there's a statesman introducing a bill to cut down on thermal pollution." The authors' suggestion that unusually intense gravitational interactions with Saturn and other moons is more realistic. Probably.