Space liquids
December 18, 2009
Astronomers in Berlin have spotted a gigantic sea of liquid on Saturn's moon Titan. With an area of as many as 400,000 square kilometers (154,400 square miles), the "Kraken Mare" is larger than the largest sea on earth, the Caspian Sea.
While data sent back to earth by the Cassini spacecraft since 2004 has suggested fluids are present on Titan, latest infrared spectrometer images of sunlight reflecting off an area of the moon's northern pole indicates the presence of liquid methane or other hydrocarbons.
The images were made in July during Cassini's 59th orbit around Titan from a distance of 200,000 kilometers (124,274 miles).
Smooth surface
Professor Ralf Jaumann of the German Aerospace Center said the evidence of fluids is conclusive.
"We have been searching for this for a long time, and our idea was it would be possible to prove the presence of fluids if we could capture the reflection of the sun. The sun only reflects off liquids, and we saw it do so."
Ice surfaces would be rough and non-reflective because of erosion and sediments of atmospheric particles, he said.
Titan is the largest of Saturn's moons. It is cloaked in a thick atmosphere which obscures visibility of its surface, and the scientists studied images based on infrared wavelengths which penetrate the atmosphere. A smaller sea of liquid ethane was discovered in 2008 on Titan's southern pole.
Spacecraft outlives mission
German Aerospace Center researcher Ulrich Köhler said radar images from 2006 confirmed the coastline of Kraken Mare, but it wasn't then possible to prove the presence of liquids.
"Until recently it has not been completely clear if the individual traces of fluids on this moon were current or left over from the distant past," he said. "And now this seems to acknowledge that there currently really are liquids on a planetary body other than the Earth. It must be a very smooth surface, so it can really only be a liquid."
The Cassini spacecraft was launched in 1997 and completed the four-year mission it was designed for in 2008, but is still functioning well. The Kraken Mare was named after a sea monster in Norse mythology.
Researchers from the German Aerospace Center will present their findings Friday at the yearly conference of the American Geophysical Union in San Francisco.
Author: Gerhard Schneibel
Editor: Nigel Tandy