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Titan may be riddled with caves

Posted by zaran_klreza on July 26, 2006, 9:56 am
200.77.66.100

Strange, but true, from:
http://www.newscientistspace.com/article/dn9588-
The highlands of Titan may be riddled with caves, according to the latest images of Saturn's giant moon.
On 30 April, the Cassini spacecraft flew over a large bright region called Xanadu that spans about 4000 kilometres.
Xanadu was already thought to be a highland area, where bright hills of ice poke up above Titan's dark sooty plains. A new picture made with the spacecraft's haze-penetrating radar confirms this (watch a 6.7 Mb QuickTime movie of the radar images).
In fact, the interior of the region is crossed by mountain chains that rise more than a kilometre high – while most of the moon appears relatively flat. "These are the highest mountains measured on Titan so far," says radar team member Ralph Lorenz of the University of Arizona in Tucson, US.
But it seems that the mountains are not solid. The radio waves bouncing off Xanadu reveal that it has peculiar electrical properties – specifically a low dielectric constant.
"The only reasonable material makeup that could have a very low dielectric constant and still hold together enough to form the structures that we see would be some sort of porous stuff – most likely porous water ice," says another team member, Steve Wall of NASA's Jet Propulsion Laboratory in Pasadena, California, US.
Dark patches
He suggests the region might be filled with caverns, presumably carved out by the methane rain that is thought to fall on Titan (see Methane rivers and rain shape Titan's surface).
That rain would also have created the long river valleys that meander among the hills nearer the fringes of Xanadu. Cassini scientists speculate that these rivers could carry ice grains down to the plains to form the dunes seen on much of Titan's surface (see Colossal dunes swathe Saturn's giant moon).
The highlands are also marked by small, dark patches that may be methane lakes – although, as elsewhere on the moon, there is no strong evidence of liquid still present on the surface.
That could change this weekend when Cassini makes its first pass above the wintry north pole of Titan. The poles are the most likely places for lakes or seas to survive because they are cold enough to prevent any liquid methane on the surface from evaporating quickly.
But what if there are no lakes near the pole? "If we don't find them there, then I will begin to wonder if they are visible on Titan at all," Lorenz told New Scientist

Message Thread

Titan may be riddled with caves - zaran_klreza July 26, 2006, 9:56 am
- Life imitates art? *nt* - Michael Hoskin July 30, 2006, 6:52 am
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--Previous Message-- : Strange, but true, from: : http://www.newscientistspace.com/article/dn9588- : : The highlands of Titan may be riddled with : caves, according to the latest images of : Saturn's giant moon. : : On 30 April, the Cassini spacecraft flew : over a large bright region called Xanadu : that spans about 4000 kilometres. : : Xanadu was already thought to be a highland : area, where bright hills of ice poke up : above Titan's dark sooty plains. A new : picture made with the spacecraft's : haze-penetrating radar confirms this (watch : a 6.7 Mb QuickTime movie of the radar : images). : : In fact, the interior of the region is : crossed by mountain chains that rise more : than a kilometre high – while most of the : moon appears relatively flat. "These : are the highest mountains measured on Titan : so far," says radar team member Ralph : Lorenz of the University of Arizona in : Tucson, US. : : But it seems that the mountains are not : solid. The radio waves bouncing off Xanadu : reveal that it has peculiar electrical : properties – specifically a low dielectric : constant. : : "The only reasonable material makeup : that could have a very low dielectric : constant and still hold together enough to : form the structures that we see would be : some sort of porous stuff – most likely : porous water ice," says another team : member, Steve Wall of NASA's Jet Propulsion : Laboratory in Pasadena, California, US. : : Dark patches : He suggests the region might be filled with : caverns, presumably carved out by the : methane rain that is thought to fall on : Titan (see Methane rivers and rain shape : Titan's surface). : : That rain would also have created the long : river valleys that meander among the hills : nearer the fringes of Xanadu. Cassini : scientists speculate that these rivers could : carry ice grains down to the plains to form : the dunes seen on much of Titan's surface : (see Colossal dunes swathe Saturn's giant : moon). : : The highlands are also marked by small, dark : patches that may be methane lakes – : although, as elsewhere on the moon, there is : no strong evidence of liquid still present : on the surface. : : That could change this weekend when Cassini : makes its first pass above the wintry north : pole of Titan. The poles are the most likely : places for lakes or seas to survive because : they are cold enough to prevent any liquid : methane on the surface from evaporating : quickly. : : But what if there are no lakes near the : pole? "If we don't find them there, : then I will begin to wonder if they are : visible on Titan at all," Lorenz told : New Scientist : :

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