There’s Methane in Them Thar Hills

JPL’s Cassini orbiter around Saturn got another look at its methane-clouded moon, Titan, on October 25. These closest-ever shots from the Visual and Infrared Mapping Spectrometer have a maximum resolution of 400 meters per pixel—about the size of the JPL campus, excluding parking lots—and in the image below left are overlaid on previous VIMS data. The close-up below right reveals a mountain range about 150 kilometers long and 1.5 kilometers high. This mini-Sierra Nevada has “snow”-clad summits (possibly of frozen methane) and appears to have been formed when subsurface material welled up in cracks between diverging tectonic plates, much as the mid-ocean ridges formed on Earth. “These mountains are probably hard as rock, made of icy materials, and are coated with different layers of organics,” says Larry Soderblom (PhD ’70), a Cassini interdisciplinary scientist with the U.S. Geological Survey in Flagstaff, Arizona. The mountain range had been seen in previous radar-mapping passes, but its signature had been difficult to interpret. In the infrared, however, the shadow it casts is clearly visible.