1 of 2 | On February 24, 2009, the NASA/ESA Hubble Space Telescope captured a photo sequence of four moons of Saturn passing in front of their parent planet. The moons, from far left to right, are the white icy moons Enceladus and Dione, the large orange moon Titan, and icy Mimas. Due to the angle of the Sun, they are each preceded by their own shadow. (UPI PHoto/NASA, ESA and the Hubble Heritage Team) |
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GREENBELT, Md., Oct. 7 (UPI) -- A moon of Saturn that should be frozen solid may have liquid oceans, thanks to a "wobble" it experiences as it orbits the ringed planet, researchers say.
With temperatures around 324 degrees below zero Fahrenheit, the surface of Enceladus is indeed frozen, but in 2005 NASA's Cassini spacecraft discovered a giant plume of water gushing from cracks in the surface over the moon's south pole, suggesting there was a reservoir of water beneath the ice, a release from NASA's Goddard Space Center said Thursday.
Analysis of the plume by Cassini shows the water is salty, indicating the reservoir is large, perhaps even a global subsurface ocean.
Scientists estimate the south polar heating is equivalent to a continuous release of about 13 billion watts of energy.
Researchers say tidal heating may be keeping Enceladus warm enough for liquid water to remain under its surface.
Enceladus' orbit around Saturn is slightly oval-shaped and the moon moves closer in and then farther away as it travels around the planet. The fluctuating gravitational tug on Enceladus causes it to flex slightly, and the flexing, called gravitational tidal forcing, generates heat from friction deep within Enceladus.
Also, the moon's rotation as it orbits may not be uniform, scientists say, and additional heat caused by this "wobble" could be five times as much as that created by tidal heating.
The extra heat makes it likely that Enceladus' ocean could be long-lived, significant to a search for life on the orbiting moon, because life requires a stable environment to develop, NASA scientists say.
