Life found on Saturn moon - Titan

Hydrocarbon lakes on Titan may harbour exotic forms of life (Illustration: NASA/JPL)

Hints of life found on Saturn moon

Two potential signatures of life on Saturn's moon Titan have been found by the Cassini spacecraft. But scientists are quick to point out that non-biological chemical reactions could also be behind the observations.

Titan is much too cold to support liquid water on its surface, but some scientists have suggested that exotic life-forms could live in the lakes of liquid methane or ethane that dot the surface.

In 2005, Chris McKay of NASA's Ames Research Center in Moffett Field and Heather R Smith of the International Space University in Strasbourg, France, calculated that such microbes could eke out an existance by breathing in hydrogen gas and eating the organic molecule acetylene, creating methane in the process.

This would result in a lack of acetylene on Titan and a depletion of hydrogen close to the moon's surface, where the microbes would live, they said.

Now, measurements from the Cassini spacecraft have borne out these predictions, hinting that life may be present.

Hungry for hydrogen

Infrared spectra of Titan's surface taken with the Visual and Infrared Mapping Spectrometer (VIMS) showed no sign of acetylene, even though ultraviolet sunlight should constantly trigger its production in the moon's thick atmosphere.

Cassini measurements also suggest hydrogen is disappearing near Titan's surface, according to a study to appear in Icarus.

Observations with the spacecraft's Ion and Neutral Mass Spectrometer and its Composite Infrared Spectrometer revealed that hydrogen produced by UV-triggered chemical reactions in the atmosphere is flowing both upwards and off into space as well as down towards the surface.