An international team of scientists has suggested that asteroid impact craters may be the best place to look for signs of life on Mars and other planets.
The study, published in the journal Astrobiology, reports the discovery of tiny organisms underneath a site where an asteroid crashed some 35 million years ago.
The team believes that the organisms are evidence that such craters provide refuge for microbes, sheltering them from the effects of the changing seasons and events such as global warming or ice ages. The research also suggests that crater sites on Mars may also be hiding life, and that drilling beneath them could lead to evidence of similar life forms.
The scientists drilled about 1.76 km below one of the largest asteroid impact craters on Earth – Chesapeake Bay impact structure in the United States.
Samples from below ground showed that microbes are unevenly spread throughout the rock, suggesting that the environment is continuing to settle 35 million years after impact.
The team suggests that heat from the impact of an asteroid collision would kill everything at the surface, but fractures to rocks deep below would enable water and nutrients to flow in and support life. Some organisms grow by absorbing elements such as iron from rock.
“The deeply fractured areas around impact craters can provide a safe haven in which microbes can flourish for long periods of time,” concluded lead author Prof. Charles Cockell of the University of Edinburgh’s School of Physics and Astronomy. “Our findings suggest that the subsurface of craters on Mars might be a promising place to search for evidence of life.”