NASA’s Curiosity rover has been exploring the surface of Mars for a decade in search of life beyond Earth, and made some intriguing findings that may hint at evidence of past life on the Red Planet.
Scientists have discovered that several of the powered rock samples collected from the surface of Mars are rich in a type of carbon that on Earth is linked to biological processes.
Carbon is important since this element is found in all life on Earth and flows through the air, water, and ground in a cycle that’s well understood thanks to isotope measurements.
Paul Mahaffy, who served as the principal investigator of the Sample Analysis at Mars (SAM) chemistry lab aboard Curiosity said that although the findings are interesting, they would need more evidence to be able to say they’ve identified life.
Various explanations for the unusual carbon signals detected were outlined in a report of the findings, but scientists warn that Mars and Earth are so different that they can’t draw conclusions based on Earth examples.
“The hardest thing is letting go of Earth and letting go of that bias that we have and really trying to get into the fundamentals of the chemistry, physics and environmental processes on Mars,” said Goddard astrobiologist Jennifer L. Eigenbrode, who participated in the carbon study.
Scientists have explored three possible explanations for the new find. They outline that the biological explanation presented is inspired by Earth life, and “involves ancient bacteria in the surface that would have produced a unique carbon signature as they released methane into the atmosphere where ultraviolet light would have converted that gas into larger, more complex molecules. These new molecules would have rained down to the surface and now could be preserved with their distinct carbon signature in Martian rocks,” a statement explains.
The other hypotheses explore nonbiological explanations as one suggests the carbon signature could have resulted from the interaction of ultraviolet light with carbon dioxide gas in the Martian atmosphere, while the other points to the carbon which could have been left behind from a rare event hundreds of millions of years ago.
According to the statement, “living creatures on Earth use the smaller, lighter carbon 12 atom to metabolize food or for photosynthesis versus the heavier carbon 13 atom. Thus, significantly more carbon 12 than carbon 13 in ancient rocks, along with other evidence, suggests to scientists they’re looking at signatures of life-related chemistry”.
Researchers have discovered that almost half of their samples had large amounts of carbon 12 which came from five distinct locations in Gale crater.
Andrew Steele, a Curiosity scientist based at the Carnegie Institution for Science in Washington, D.C said that scientists are in the early stages of understanding how carbon cycles on Mars work.
“Defining the carbon cycle on Mars is absolutely key to trying to understand how life could fit into that cycle,” Steele said. “We have done that really successfully on Earth, but we are just beginning to define that cycle for Mars.”
Picture: Twitter / @MarsCuriosity