Saturn moon's 'buoyant' mountains perplex, befuddle
What if Titan's crust isn't thin and brittle like an eggshell, but thick and rigid, with huge floating mountains? What does that do to the implications for ice volcanoes, subsurface seas, and life?
Titan is tricky. The enormous moon of Saturn has topography like Earth's, but it's made of ice instead of rock. Throw in an opaque (and poisonous) atmosphere and a space probe that only occasionally passes by to pick up a new swath of data, and you have a truly mysterious planet. Er, moon.Skip to next paragraph
In Pictures Cassini's view of Saturn
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"Titan has been a hard planet to study," says Chuck Wood, a member of the Cassini science team based at the Planetary Science Institute in Tucson, adding, "It's bigger than Mercury; that's why we call it a planet."
The opaque atmosphere has defeated Cassini's impressive cameras, leaving scientists relying on low-resolution radar and other instruments to interpret Titan's mysteries. "It's almost like seeing the moon with telescopes from Earth," says Dr. Wood. "It's hard to have enough resolution to be confident in what we're seeing."
Despite the challenges, scientists have been announcing new and bizarre findings from Titan, Saturn's biggest (and arguably weirdest) moon ever since NASA's Cassini-Huygens mission arrived at Saturn in 2004.
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Titan is a "deranged version of Earth!" scientists said. Titan has lakes! When scientists dropped the Huygens probe through Titan's thick atmosphere, they saw shorelines! Rivers! Evidence of "exotic and exciting" methane-ice-sludge volcanoes! Five years later, a methane rainstorm made more headlines, followed by Titan's potential for bizarre and smelly lifeforms, mile-wide dunes shaped by 'backward' winds, and theories about Titan-esque DNA.
Last year, the liquid story got more involved, with the discovery of a humongous methane lake in the (comparatively warm) tropics and growing evidence for a subsurface ocean underneath a frozen crust.
With that model, Titan is like an egg: liquid on the inside, thin and brittle on the outside. And there may or may not be a solid (or solid-ish) "yolk" somewhere deep inside.