The Lakes of Titan - Cassini Mission Detects "Molecules Like Amino Acids, the Building Blocks of Life"
NASA’s Cassini spacecraft has imaged methane lakes in the “tropics” of Saturn’s moon Titan. One of the lakes appears to be about half the size of Utah’s Great Salt Lake, with a depth of at least 3 feet (1 meter),an unexpected result, because models had assumed the long-standing bodies of liquid would only exist at the poles.
"A likely supplier is an underground aquifer," said Caitlin Griffith, the paper’s lead author and a Cassini team associate at the University of Arizona, Tucson. “In essence, Titan may have oases.”
“An aquifer could explain one of the puzzling questions about the existence of methane, which is continually depleted,” Griffith added. “Methane is a progenitor of Titan’s organic chemistry, which likely produces interesting molecules like amino acids, the building blocks of life.”
Global circulation models of Titan have theorized that liquid methane in the moon’s equatorial region evaporates and is carried by wind to the north and south poles, where cooler temperatures cause methane to condense. When it falls to the surface, it forms the polar lakes. On Earth, water is similarly transported by the circulation, yet the oceans also transport water, thereby countering the atmospheric effects.
Some regions could be shallow, ankle-deep puddles. Cassini’s radar mapper has seen lakes in the polar region, but hasn’t detected any lakes at low latitudes.
Ref.: Caitlin A. Griffith et al., Possible tropical lakes on Titan from observations of dark terrain, Nature, 2012, DOI: 10.1038/nature11165