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Archive for the ‘Astrobiology’ Category

More News of Life on Mars and Saturn’s Titan

For several years now, WSU astrobiologist¬†Dirk Schulze-Makuch has been building a case for extraterrestrial life. Just this spring, he and several colleagues reported finding microbial life in an incredibly inhospitable lake of asphalt in the Caribbean, suggesting life might similarly be found in the liquid hydrocarbon environments of Saturn’s moon, Titan.

Now comes word that ancient Mars seems to have had a wet, non-acidic environment favorable to life. Researchers led by NASA’s Richard Morris and writing in the journal Science say the evidence lies in an outcrop of rock with high amounts of carbonate, which forms in wet conditions and dissolves in acid.

Carbonate-Containing Martian Rocks (color added)/Image courtesy of NASA, JPL-Caltech, and Cornell University

The finding, says Schulze-Makuch, “supports the notion of a warmer and wetter early Mars with substantial amounts of liquid water on its surface, probably in the form of oceans. Thus, early Mars was certainly a habitable planet and the origin of single-cellular life on Mars or transfer of that type of life from Earth to Mars or vice versa is certainly plausible.”

No sooner does Schulze-Makuch say this when we read of the Cassini spacecraft finding no sign of acetylene on Titan. A separate study found evidence that hydrogen is disappearing near the moon’s surface. The discoveries support a theory that Titanic microbes could survive by breathing hydrogen gas and eating acetylene, producing methane as a result.

Schulze-Makuch calls the discoveries “extremely intriguing.”

“A biological explanation would be quite plausible as hydrogen is the most basic ingredient for metabolism on Earth and acetylene is an energy-rich molecule that could be harvested as part of a methanogenic metabolism on Titan,” he says.

In fact, he predicted as much in 2005, writing with David Grinspoon in the journal Astrobiology.

“Obviously, inorganic explanations have to be eliminated as a possibility before we conclude that biology is the cause,” he says. “However, an inorganic explanation is difficult to invoke since a strong catalyst would be needed to remove the hydrogen and acetylene falling from Titan’s atmosphere under the very cold surface temperatures on Titan. Indeed, what is observed is exactly what we would expect if life on Titan is present that uses hydrogen and acetylene in its metabolic pathway and produces methane as a result.”

Very cool video of how the Spirit¬†Mars Rover operates on rock can be seen here. You can also read a lot more about Schulze-Makuch’s thinking on extraterrestrial life in his recent and eminently readable book, We Are Not Alone.