Science & Technology - Posted by Anne Ju-Cornell on Monday, July 9, 2012 11:16 - 0 Comments
Saturn’s methane moon hides buried ocean
CORNELL (US) — Methane in the atmosphere of Saturn’s moon Titan was likely influenced by an ocean of water recently discovered 100 kilometers below the moon’s surface, a new study shows.
Using data from six Cassini spacecraft flybys of Titan between 2006 and 2011, scientists detected the presence of the subsurface ocean from the moon’s subtle squeezing and stretching as it orbited Saturn.
As reported in the journal Science, the layer of liquid water underneath its icy shell makes Titan a possible abode for life.
This artist’s concept shows a possible scenario for the internal structure of Titan, as suggested by data from NASA’s Cassini spacecraft. Scientists have been trying to determine what is under Titan’s organic-rich atmosphere and icy crust. Data from the radio science experiment make the strongest case yet for a global subsurface ocean, sitting above a subsurface layer of high-pressure ice and a water-infused silicate core. (Credit: A. Tavani)
Straight from the Source
Titan is the only moon in our solar system with a dense atmosphere—denser than Earth’s. But most fascinating of all, says Jonathan Lunine, professor of physical sciences at Cornell University, is the large amount of methane, the simplest organic molecule, in its atmosphere.
Picture lakes and rivers on Titan’s surface not of water, but of bubbling methane and maybe even geysers like Old Faithful.
“All the things water does on Earth, methane does on Titan,” Lunine says. The presence of a liquid water layer within Titan can help scientists understand how methane is stored in the moon’s interior and how it may come up to the surface.
“Everything that is unique about Titan derives from the presence of abundant methane, yet the methane in the atmosphere is unstable and will be destroyed on geologically short timescales.”
The observations that led to the discovery of the ocean, Lunine adds, are impressive feats of precision data analysis by the international Cassini research team led by Luciano Iess of Sapienza University in Rome.
“The team was able to measure incredibly small accelerations of the spacecraft due to the presence of Titan—changes smaller than a millionth the acceleration due to gravity on the Earth. At those accelerations it would take a car roughly a month to go from 0 to 60 miles per hour,” Lunine says.
Because every season on Titan is seven years long, Lunine adds, researchers hope Cassini will continue to be supported by NASA through 2017 so they can observe Titan at the onset of southern winter and northern summer.
“Most of the methane lakes and seas are near the north pole . . . we’ve never actually seen what happens when the sun shines directly on the methane lakes, so we are looking forward to that,” Lunine says.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency, and is managed by Jet Propulsion Laboratory at the California Institute of Technology.
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