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.
In fact, the interior of the region is crossed by mountain chains that rise more than a kilometre high â€“ 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 â€“ 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 â€“ most likely porous water ice,” says another team member, Steve Wall of NASA’s Jet Propulsion Laboratory in Pasadena, California, US.
He suggests the region might be filled with caverns, presumably carved out by the methane rain that is thought to fall on Titan…
(Another piece of colour for IGNITION CITY)