Mars craters a 'safe haven' for life?

Asteroid craters on Earth shelter life -- and they might do so on planets like Mars as well, a new study suggests.

Micro-organisms have been discovered living deep underneath a site in the U.S. where an asteroid crashed some 35 million years ago, wrote Charles Cockell of the University of Edinburgh’s School of Physics and Astronomy – and similar craters on Mars would be a great spot to probe for aliens.

“The subsurface of craters on Mars might be a promising place to search for evidence of life,” Cockell wrote in this month’s edition of the science journal Astrobiology. “The deeply fractured areas around impact craters can provide a safe haven in which microbes can flourish for long periods of time.”

NASA and other leading scientists told they agree -- and the discovery by Cockell and colleagues should impact future U.S. research on Mars.

“The planetary science community recognizes that the deep subsurface promises to be a protected habitat for potential Martian life," NASA spokesman Dwayne C. Brown told

To get beneath the crater on Earth, Cockell and co. drilled nearly two kilometers under one of the largest asteroid impact craters around, in the Chesapeake Bay area. Rock samples showed microbes are unevenly spread throughout the crater formation, which implies the environment is still settling 35 million years after impact.

Heat from the impact of an asteroid collision would have killed everything at the surface of the crater, but fractures on rocks deep below enabled water and nutrients to flow in and support life.

The surface of Mars is seemingly inhospitable to life. But the new research shows that a few inches underground, Mars may be a very different planet, agreed a former leading NASA scientist.


"Due to its very thin atmosphere and lack of a planetary dipole magnetic field, the surface of Mars is consistently bombarded by solar ultraviolet radiation and solar-emitted particulate radiation, e.g., the solar wind, making the surface of Mars an inhospitabe site for living systems," Dr. Joel Levine told

"However, the sub-surface of Mars, even a few inches below the surface, may be protected from solar ultraviolet and particulate radiation and life may find a hospitable zone there. Asteroid and meteor impacts provide a 'window' to the near-surface, the subsurface of Mars -- and may provide a unique opportunity to search for life there."

Levine retired from the NASA Langley Research Center last year after 41 years of federal service and joined the College of William and Mary as Research Professor in the Department of Applied Science, where he continues his research on the question of life on Mars -- including the possibility of flying a rocket-powered, robotic airplane a mile above the surface of Mars to detect trace gases of biological origin that may be produced by sub-surface life.

According to James Wray, an assistant professor in Georgia Tech's School of Earth and Atmospheric Sciences and a scientific team member for an upcoming NASA mission to Mars, the Martian surface today is too cold -- and the air too thin -- for liquid water. But there’s water ice in the subsurface, and if a source of heat is supplied, it could be melted.

"Asteroid impacts definitely provide heat, and we know that they happen once or more per week on Mars," he told

Wray said NASA's HiRISE camera has directly observed over 200 new impact craters formed during the past few years.

But he sounds a note of scientific caution about the Edinburgh researchers' findings.

"To create a long-term wet environment in the subsurface would require a large impact, and craters as large as the Chesapeake Bay structure described in this study probably only form every few million years or even tens of millions of years apart on Mars," Wray told

Another challenge is that it would be very difficult to drill over a mile into the Martian subsurface without having astronauts on the surface.

"But when we do send humans to Mars in the future, choosing a landing site near a relatively fresh large crater in an icy terrain would not be a bad idea," he said.

Deeper exploration of the Martian surface, without astronauts, is poised to start this summer, with the arrival in August of NASA’s Curiosity Rover on the Martian surface.

"The full suite of instruments on Curiosity are designed to assess whether Mars once could have had conditions to support life,” Brown told

“Certainly, finding evidence of any kind on this subject would be incredibly exciting."