Eigenbrode said the molecules are amazingly robust. They were found close to the surface and were exposed to ionizing radiation, which can degrade organics.
“We think they haven’t changed over time, as this form of organic matter is resistant to changes,” she said. “But if life was on early Mars and other conditions were favorable, this means the organic biosignatures would be preserved.”
A drill on the Curiosity rover made a 5 centimeter hole in mudstones in Gale Crater at sites called Mojave and Confidence Hills. The rover then heated the rock samples to over 900 degrees Fahrenheit (500 degrees Celsius) and analyzed the molecules that were released. The process revealed the presence of several organic molecules, including carbon, thiophenes, benzene, toluene, and small carbon chains, such as propane or butene.
Like the methane discovery, NASA had also announced in 2014 the detection of organic molecules.
“In 2014, we reported the detection of chlorinated molecules, which is a significant discovery,” Eigenbrode told Seeker. “We had hoped we would find it with the Viking landers in the 1970’s, but we didn’t. While Curiosity’s first detection in 2014 was not what you typically find in natural samples, it did give us a lot of motivation to keep looking because we thought there had to be other layers of organic molecules.”
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Curiosity found new organic layers just four miles away from the first site. And Eigenbrode said the new find provides another boost for research on the Red Planet.
Ashwin Vasavada, project scientist with the Curiosity team, said the longevity of the Curiosity mission was key to both finds
“Without having the rover surface for over 6 years, we couldn’t have made these detections,” he said. “And these findings give upcoming missions like ESA’s ExoMars and the Mars 2020 rover a lot of work ahead.”