A new analysis of 40-year-old data has revealed that NASA’s exploration spacecraft may have detected evidence of life on Mars decades before the discovery of organic matter on the Red Planet, but the results likely were destroyed before reaching Earth.
The 1976 Viking rovers were sent to Mars in search of organic matter, but returned empty-handed.
By reexamining data from the Viking mission, the researchers identified chlorobenzene, a chlorinated organic material created in reaction with salt in Martian soil, according to findings published in the Journal of Geophysical Research: Planets .
In 2008, a NASA mission exploring the north pole of Mars discovered that this salt, called perchlorate and used in rockets and fireworks, became explosive when heated excessively.
This means that Viking, who used an instrument to heat soil samples to locate organic matter, was able to burn off the carbon molecules in the soil when the perchlorate caught fire.
Most Martian missions have searched for organic matter by a heating method, which is likely the cause of the data lag.
The Curiosity rover, which identified organic molecules in three-billion-year-old Martian rocks, used the same method, heating the samples in a furnace to over 900 degrees Fahrenheit to release concentrates of sulfur and carbon organic, NASA said.
The sedimentary rock, called mudstone, probably did not contain perchlorate.
“It was completely unexpected and inconsistent with what we knew,” NASA planetary scientist Chris McKay told New Scientist magazine. “You have a new vision and you realize that everything you knew was wrong. »
The presence of organic molecules could mean that life exists on Mars, or once did. But organic molecules can also be created by non-biological processes, like chemical reactions that don’t require life.
The study’s lead author, Melissa Guzman, speculated that chlorobenzene may have traveled from Earth on the Viking landers, contaminating their instruments.
The Curiosity team also reported seasonally varying levels of methane, the simplest organic molecule, providing further evidence for the possibility of living things on Mars.
And while 95% of Earth’s methane is generated by biological processes, such as the decay of livestock and natural gas leaks, the presence of methane is no guarantee of life on the planet.
“This is a gas in the atmosphere of Mars that shouldn’t be there,” Chris Webster, a scientist at NASA’s Jet Propulsion Laboratory, told National Geographic.
Another study published a few weeks earlier in the same journal revealed inorganic secrets about the Red Planet’s past.
The researchers found nearly 800 “ghost dunes” or sand shells of ancient dunes, evidence that water and lava covered the Martian sand dunes with sediments that hardened before being blown away.
According to the researchers, ancient microbes could still be living in dunes containing ancient sand.
“There’s probably nothing there,” study author Mackenzie Day told the American Geophysical Union. “But if there was ever anything on Mars, it’s a better than average place to look. »