Carolyn Porco, Imaging Team Lead. Titan is unlike Mars and the icy moons of Jupiter, which have little or no atmosphere. So the "techniques that we've used for interpreting airless bodies, all those methods of examining solid surfaces from planetary spacecraft that we have learned over the last half century," don't apply, says Porco. "We can't use that on Titan, because it's a very different environment." Image Credit: NASA/JPL