Life On Titan

Whether there is life on Titan, the largest moon of Saturn, is at present an open question and a topic of scientific evaluation and research.

Titan is far colder than Earth, and its surface seems to lack liquid water; factors which have led some scientists to consider life there unlikely. On the other hand, the following points have been made in favor of Titan's suitability to sustain some form of life:

• Titan appears to have lakes of liquid ethane and/or liquid methane on its surface, as well as rivers and seas, which some scientific models (still tentative and debated) suggest could support non-water-based life.
• It has also been suggested that life may exist in a sub-surface ocean consisting of water and ammonia. Recent data from NASA's Cassini spacecraft have strengthened evidence that Titan likely harbors a layer of liquid water under its ice shell.
• Titan is the only known natural satellite (moon) in the Solar System that is known to have a fully developed atmosphere that consists of more than trace gases. Titan's atmosphere is thick, chemically active, and is known to be rich in organic compounds; this has led to speculation about whether chemical precursors of life may have been generated there.
• The atmosphere also contains hydrogen gas, which is cycling through the atmosphere and the surface environment, and which living things comparable to Earth methanogens could combine with some of the organic compounds (such as acetylene) to obtain energy.

In June 2010, scientists analysing data from the Cassini–Huygens mission reported anomalies in the atmosphere near the surface which could be consistent with the presence of methane-producing organisms, but may alternatively be due to non-living chemical or meteorological processes. The Cassini–Huygens mission was not equipped to provide direct evidence for biology or complex organics.