Titan IV 
Not many folks go sailing at this time of year. The weather is too cold, and many of the lakes are too icy. That doesn't stop them from planning sailing excursions, though. Scientists in the United States and elsewhere, for example, are pondering an expedition to Ligeia Mare -- a sea on Titan, the largest moon of Saturn.
The Cassini spacecraft has revealed more than 400 lakes and seas on Titan, most of which are clustered around the poles. Ligeia Mare is one of the biggest. It covers about 40,000 square miles, making it bigger than Lake Superior here on Earth.
It's not filled with water, though; Titan is so cold that water is frozen as hard as granite. Instead, it's filled with liquid methane and ethane and other hydrocarbons.
Scientists hope to drop a probe into the lake and monitor it as it floats with the current. The mission is the Titan Mare Explorer, and it's still in the early planning stages. If it flies, though, it'll aim at Ligeia Mare.
Winds atop Ligeia vary from about one to two miles per hour. And because of the tides, the lake level varies by about three feet per day. The combination of tides and winds would push the probe several miles a day, allowing it to study much of the basin over the course of several weeks. And the tides are strong enough to stir up material from the bottom of the lake, so the probe's instruments could sample everything from the surface to the sea floor -- providing a thorough look at a frigid sea.
Script by Damond Benningfield, Copyright 2010