The surprise discoveries, made using an orbiting spacecraft, are revealed by two separate teams reporting in two science publications, Icarus and the Journal of Geophysical Research.
Data from NASA’s Cassini probe has analysed the complex chemisty on the surface of Titan – the only moon known to have a dense atmosphere.
Its surface is covered with mountains, lakes and rivers which has led astronomers to call it the most Earth-like world in the solar system. It is thought there could also be a vast underground ocean.
Organic chemicals had already been detected on the 3,200-mile wide moon. But the liquid on Titan is not water but methane and the scientists expect life there to be methane-based.
The paper in Icarus shows that hydrogen gas flowing down through Titan’s atmosphere mysteriously disappears at the surface, suggesting it could be being breathed by alien bugs.
The second paper reports that there is a lack of the chemical acetylene on the surface, leading scientists to believe that it may be being consumed like food by life.
Scientists had expected sunlight interacting with chemicals in the atmosphere to produce acetylene that falls down to coat the Titan surface. But Cassini detected no acetylene on the surface.
Experts caution that there could be other expananations for the results observed. But taken together, they fulfll two important conditions necessary for methane-based life to exist, according to NASA’s news release.
NASA astrobiologist Chris McKay, of California, who drew up the list of conditions, said: “We suggested hydrogen consumption because it’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth.
“If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth.”
The disappearing hydrogen was noted by Cassini scientist Darrell Strobel, of Johns Hopkins University in Baltimore, Maryland. The absence of acetylene was discovered by a team led by colleague Roger Clark, of the U.S. Geological Survey in Denver, Colorado.
Scientists say Titan resembles Earth as it was four billion years ago and so could be a new cradle for life. They believe that when the sun swells up, swallowing the Earth, conditions for life could be ideal on a warmed-up Titan.
Professor John Zarnecki, of the Open University, who landed a probe called Huygens on Titan in January 2005, has told Skymania: “We believe the chemistry is there for life to form. It just needs heat and warmth to kick-start the process. In four billion years time, when the sun swells into a red giant, it could be paradise on Titan.”
Professor Zarnecki is part of a UK/US team proposing an exciting mission to send a probe to float on Titan’s lakes.
★ Keep up with space news and observing tips. Click here to sign up for alerts to our latest reports. No spam ever – we promise!
