Glass detected in impact craters on the surface of Mars could hold evidence of ancient life on the Red Planet, scientists say.
As the molten glass created in the extreme heat of violent impacts cooled and solidified, it may have encapsulated biosignatures of any ancient life existing at the time of the impact, they suggest.
The process has been seen on the Earth, says Brown University geologist Peter Schultz.
In a study published last year, Brown and his colleagues described finding organic molecules and even plant matter preserved in glass created in an impact in Argentina millions of years ago.
There is no reason to believe similar processes could not have occurred on Mars, say other Brown researchers who conducted a new study analyzing data from NASA's Mars Reconnaissance Orbiter to confirm the present of impact glass on Mars.
"The work done by Pete and others showed us that glasses are potentially important for preserving biosignatures," says lead author and Brown doctoral student Kevin Cannon. "Knowing that, we wanted to go look for them on Mars and that's what we did here."
Cannon and his co-author Jack Mustard, a professor of Earth, environmental and planetary sciences, report their study confirms large deposits of glass exist in a number of ancient but well-preserved impact craters in various spots on the Martian surface.
In laboratory experiments, the researchers determined what the spectral signal of Martian glass would be as sunlight bounces off it, then designed a computer algorithm that went searching for that signal in the mass of data gathered by the NASA orbiter.
"The researchers' analysis suggests glass deposits are relatively common impact features on Mars," said Jim Green, director of the space agency's planetary science division. "These areas could be targets for future exploration as our robotic scientific explorers pave the way on the journey to Mars with humans in the 2030s."
The Brown researchers say they have the perfect target in mind, an impact crater called Hargraves in a region that is a leading candidate for a landing site for NASA's Mars 2020 rover mission.
A rover landing there would be perfectly situated to study Martian impact glass for evidence of ancient life, says Mustard.
"If you had an impact that dug in and sampled that subsurface environment, it's possible that some of it might be preserved in a glassy component," he says. "That makes this a pretty compelling place to go look around, and possibly return a sample."
