Telescope may have found liquid seas on Titan
An image from the Keck telescope shows dark regions on Titan that may be seas of liquid hydrocarbons and bright regions that may be ice-and-rock continents or highlands
July 30, 1999
Web posted at: 3:18 p.m. EDT (1918 GMT)
By Robin Lloyd
CNN Interactive Senior Writer
(CNN) -- Scientists think they have found frigid seas on Saturn's largest moon, possibly the only known liquid bodies in the solar system other than those on Earth.
A telescope atop Mauna Kea detected dark areas on Titan that astronomers with the Lawrence Livermore National Laboratory believe are seas of methane, ethane and other hydrocarbons -- not water.
"It's been predicted a long time that there might be liquid hydrocarbons there, but to actually see it is pretty exciting," said Seran Gibbard, a planetary scientist with the national laboratory affiliated with UC Berkeley.
Gibbard doubts the seas harbor life because it is too cold at Titan -- minus 180 degrees C (minus 290 degrees F) on average.
"The kind of chemical reactions you need to make life work much better at higher temperatures," she said Friday.
Titan is swamped with hydrocarbons and a nitrogen-rich atmosphere like Earth's, so scientists think it may resemble the early conditions on our planet.
The turbulent, smog clouds that blanket Titan and make it hard to study. By taking hundreds of short snapshots that freeze the clouds, scientists were able to piece together the clearest image ever of Titan, which is larger than the planet Mercury and more than 800 million miles from Earth.
The lower left corner of the image, taken three years ago by the Keck telescope atop Mauna Kea -- the world's largest telescope, shows dark areas that astronomers interpret as evidence of the hydrocarbon seas.
"Of all the light they receive from the sun, they only reflect a tiny portion of it which is one thing we think might be characteristic of liquid hydrocarbons like ethane," Gibbard said.
The powerful Hubble Space Telescope has photographed Titan before, but those images were less sharp.
The Keck was able to map surface features 150 miles in size, said Lawrence Livermore astrophysicist Claire Max.
The results are published in this month's issue of the journal Icarus.
Scientists say the dark areas also might be solid hydrocarbons.
Results to help Cassini mission
The results will help the joint U.S.-European Cassini mission, a Saturn-bound spacecraft set to drop a probe to Titan's surface in 2004.
"One way it will help is to provide a context for what they're seeing," Gibbard said.
Although water would freeze at Titan's temperatures, hydrocarbons have lower freezing points and that is one reason that scientists theorize that the dark areas are liquid, not solid.
Liquid hydrocarbons are thought to collect in Titan's atmosphere, break down and recombine in the sunlight and condense as black rain that falls to the surface, collecting in bodies like lakes, ponds and seas.
Scientists found evidence of a frozen crust atop Jupiter's moon Europa in recent years. The Galileo spacecraft is completing a mission to study Europa in the coming months and there is talk of a NASA mission to probe beneath the crust to search for water and possibly life.
In the next couple years, scientists plan to install a spectrometer on the Keck I telescope that could return data on the chemical composition of Titan's surface and atmosphere, Gibbard said.
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