The remnants of a violent, scorching meteor impact might not seem like the best place to look for signs of life, but the last couple of years have shown us that organic matter can—and does—survive these events, preserved in glass formed during the extreme temperatures. Researchers now believe they have detected deposits of this impact glass within craters on the surface of Mars, and suggest that it could also contain evidence of past life.
By analyzing the light reflected off the Red Planet’s surface, scientists are able to determine what rocks and minerals are present based on the different wavelengths of light that they either absorb or reflect, known as their spectrum. Using data collected by NASA’s Mars Reconnaissance Orbiter satellite, researchers from Brown University were able to detect the signatures unique to impact glass. That may sound simple enough, but the process was actually exceedingly complex.
“Glasses tend to be spectrally bland or weakly expressive, so signatures from the glass tend to be overwhelmed by the chunks of rock mixed in with it,” explained Jack Mustard, co-author of the paper published in the journal Geology. “But Kevin [Cannon, lead author] found a way to tease that signal out.”
To separate the signatures of rock and glass, the researchers mixed powdered rock in the lab in similar levels to those found on the surface of Mars, and then fired them in an oven to create glass. They were then able to read the spectrum of light reflected by the glass that formed, and build an algorithm that searched for these signatures in the data collected from the satellite orbiting the planet.
“Before this paper no one had been able to definitively detect [signatures of glass] on the surface [of Mars],” said Mustard. The scientists were able to pinpoint different glassy deposits around a number of different crater sites, generally on the peak that forms in the middle of craters after an impact event.
As mentioned, researchers have previously shown that organic matter can be preserved in impact glass formed when a meteor slams into the ground. This was first demonstrated when scientists from the University of Tasmania found remnants of an 800,000-year-old swamp in fragments of glass in Tasmania, and again when other researchers from Brown University discovered bits of leaves in glass formed by an impact millions of years ago.
These past discoveries have given credence to the theory of panspermia, which suggests that bits of organic matter stuck on comets and asteroids could survive the extreme conditions of space and the heat and pressure of impact, allowing them to seed other planets with life. The researchers of this new study hope that samples of the Martian glass can be collected, and hopefully returned to Earth for analysis.