Hydrocarbon glaciers and seas may dot Titan's poles - space - 14 March 2007 - New Scientist Space

Something to look forward to when the next ice age hits ?!

Hydrocarbon glaciers and seas may dot Titan's poles

Glaciers made of acetylene – on Earth, a gas used in welder's torches – may tower over the polar regions of Saturn's moon, Titan, according to a new analysis. The region near Titan's north pole also appears to harbour huge hydrocarbon seas, new radar observations reveal.
Jeffrey Kargel of the University of Arizona in Tucson, US, led a team that surveyed the zoo of organic chemicals known or suspected of being present on Titan. Then, the team analysed what form they might take in the ultra-cold, hydrocarbon-rich environment of the enigmatic moon.
At the -180º Celsius temperatures on Titan, it is cold enough for acetylene, which is a gas on Earth, to freeze solid, the researchers say.
Because the poles are a little colder than the rest of the moon, the acetylene may have accumulated there, forming kilometre-thick glaciers. Vapour could rise like steam from the glaciers, perhaps accounting for the acetylene observed in Titan's atmosphere.
Other strange things may burble up from Titan's interior from time to time. These include volcanic eruptions of liquid polyethylene, which in its solid form is used to make plastic bags on Earth.
Blobs of plastic
"Masses of polyethylene might be exuded in the liquid state to the top of the core," says Kargel, who presented the results on Tuesday at the Lunar and Planetary Science Conference in Houston, Texas, US. "And if it accumulates, big blobs of plastic could come floating up."
Icy moon expert Jeff Moore of NASA's Ames Research Center in Moffett Field, California, US, says these bizarre scenarios are possible. "Our understanding of Titan is so unconstrained that there is nothing [Kargel] said that is ruled out," Moore told New Scientist.
Ralph Lorenz of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, US, agrees that future observations are likely to reveal unexpected features on the moon.
"We do have to keep an open mind because we don't understand all the material properties," he told New Scientist. But as exciting as it would be to find something like an acetylene glacier, nothing like this has been seen so far, he adds.
Giant seas
There do appear to be plenty of liquid hydrocarbons on Titan, however. Recent observations have revealed the largest lake-like features ever seen on the moon (see Titan's largest lake rivals Earth's Caspian Sea). One of these is about as big as the Caspian Sea on Earth. Watch an animation showing lake features on Titan (large file, 28 MB).
Now, scientists studying recent radar observations by the Cassini spacecraft have turned up what appear to be even more large seas, with the largest measuring at least 100,000 square kilometres.
"We've long hypothesised about oceans on Titan and now with multiple instruments we have a first indication of seas that dwarf the lakes seen previously," says Jonathan Lunine of the University of Arizona.
Missing ethane
Oceans of liquid methane were once suggested to explain why Titan's atmosphere contains so much of the hydrocarbon, but Cassini and ground-based observatories failed to find the large bodies of liquid, instead discovering disconnected lakes and now apparent seas.
Recently, however, scientists have recalculated how much liquid methane would have to lie on the surface to account for the atmospheric observations. "Looking at what we've seen of Titan so far, there is easily that much," Lorenz says.
Still missing is a global ocean of ethane. The lakes may be a mixture of methane and ethane, but the breakdown of methane in the atmosphere over Titan's lifetime should have produced a global ocean of ethane by now.
This might be an indication that the rate of ethane production is much lower than believed, or that there is extra ethane hidden underground, Lorenz says.