Impact glass, the glass formed from the heat produced when a meteorite or comet crashes into a planet, could hold within it evidence of past Martian life. NASA’s Mars Reconnaissance Orbiter has recently detected some of this glass in Martian craters. A team of Brown University scientists has written a report about Martian impact glass data in the online journal Geology.
Impact glass on Earth has also preserved ancient signs of life.
The reason that scientists believe impact craters on Mars may hold traces of past life is that the same thing happened on Earth. Impact glass from craters formed by collisions with meteorites and comets on our own planet has preserved life before. In 2014, a study found organic molecules as well as plant matter contained in glass made during an impact that took place millions of years ago in Argentina.
Finding Martian impact glass was a tricky process.
In order to find the large impact glass deposits in certain craters on Mars, scientists had to measure the spectral band of light reflected off the surface of the planet. The tough part in this is that the glass’s signal is a weak one which tends to get drowned out by bits of rock signal. Yet, one of the Brown researchers, Kevin Cannon, figured out a way to isolate that spectral signal and measure it so as to be able to precisely identify it. Cannon, working in a lab, mixed powders of similar composition to Martian rocks and baked them in an oven to make glass. After that, he measured that glass’s spectral signal. That signal would then be compared to the one detected by the Mars Reconnaissance Orbiter.
Some of these impact features may be targets of future manned Mars missions.
When the human mission to Mars will happen sometime in the 2030s, possible targets include some of these glass-containing impact craters. One of them is called Hargraves, and it’s near a 400 mile-long trough called Nili Fossae. Nili Fossae has been singled out as a possible landing site for the rover NASA will have on the red planet in the year 2020.