Scientists Find the Lakes They Were Looking for ... on Titan ; Images of Saturn's Moon Reveal Landforms That Look a Lot, Scientists Say, like Minnesota
Peter N. Spotts writer of The Christian Science Monitor, The Christian Science Monitor
Minnesota may have a new rival for the label "land of 10,000 lakes" - but don't break out the jet skis. The rival is 944 million miles from Earth.
New images of Titan, Saturn's largest moon, reveal lakes that appear as odd-shaped splotches across the moon's far north. Lakes seen thus far range in size from just over half a mile to more than 60 miles long. Researchers say they contain liquid ethane and methane at a frosty -256 degrees F.
The find caps a month of jaw-dropping discoveries about Titan's Australia-size highlands, dubbed Xanadu, and insights into rainfall patterns on the moon - an active world sculpted by processes that are remarkably Earthlike.
"Looking at these images, they could be from Minnesota or Finland," says planetary scientist Ralph Lorenz, a member of the team announcing the results.
With the discovery, unveiled Friday, scientists heaved a sigh of relief. They had long suspected that Titan had a version of Earth's water cycle, but until now had no evidence of standing bodies of liquids that should be part of that cycle. Indeed, when NASA's Cassini spacecraft arrived at Saturn two years ago and began sending back radar images, it initially failed to turn up any convincing reservoirs.
"We were getting pretty puzzled," says Rosaly Lopes, a researcher on the Cassini radar team at NASA's Jet Propulsion Laboratory in California. Now, with the Cassini images taken July 22, the puzzle's pieces appear to be falling into place.
The lakes show up as dark patches on the surface. Several appear to be fed via liquid-carved channels. Several display what look like rims.
These are the darkest features seen so far on Titan's surface, indicating something very smooth. "It's really hard to say whether the lakes hold liquid or not," notes Dr. Lopes. "They're full of black stuff," she says, but it's unclear if the smoothness represents a glassy liquid surface or uniform deposits of hydrocarbon "meringue topping" left on lake bottoms after liquids evaporate.
Giddy, scientists await October
Confirmation could come in October, when Cassini makes another pass close by Titan that will allow the radar to cover some of the same features from a different angle. This will enable scientists to build a 3-D image that could pick up the signatures of tiny wavelets, if they are there.
The nonliquid alternatives, such as hydrocarbon sand or "fluffy soot," would yield a poorer radar signal than the ones the team has already received, Dr. …