We have been exploring the surface of Mars for a good few decades now, and in the process have discovered evidence for water and an ancient habitable environment. One thing remained elusive though – any signs of the building blocks of life.
Now that looming problem has been solved by the Curiosity rover. Reporting in the journal Science, researchers have announced that the rover’s Sample Analysis at Mars (SAM) instrument has successfully detected organics on Mars, a major breakthrough in our search for life on the Red Planet. A second paper also reports some interesting findings about methane.
“It’s a really, really big stepping stone,” Sanjeev Gupta from Imperial College London in the UK, one of the co-authors on the study, told IFLScience. “It gives us great confidence that future missions have the potential to discover life.”
Using the SAM instrument, the team led by Jennifer Eigenbrode from NASA’s Goddard Space Flight Center examined samples of Martian soil about three years ago from mudstone in Gale Crater. It was collected by Curiosity’s drill from 5 centimeters (2 inches) beneath the surface, preserved in sulfur and dating back in time between 3.2 and 3.8 billion years, when water was once present here.
While we have seen organics on Mars before, this is the first time they have been linked to larger molecules that could be indicative of life.
Heating the sample in the instrument, the team found evidence for several organic materials, including thiophene, methanethiol, and dimethyl sulfide. These are not compounds directly related to life, but they are signatures of larger molecules that could have been produced by life.
Organic molecules are ones that contain carbon and hydrogen. They can come from non-life sources, such as meteorites, and also from interactions with rocks and water. However, they also come from living matter. So we needed to find some on Mars to prove we were heading in the right direction.
“The detection of organic matter on Mars is the next step in the search for life on Mars,” Eigenbrode told IFLScience. “If the organic matter we discovered was derived from life, then it could contain signatures of that ancient life.”
Previous attempts to find organics on Mars, including the Viking missions in 1976 and the Phoenix lander in 2008, had been inconclusive. Curiosity’s discovery marks the first time we have truly known about organic compounds on the surface of Mars.
It’s important to stress that this is not a detection of life, nor is it proof that past or present life exists on Mars. It instead gives us ever-growing evidence that parts of Mars, such as Gale Crater in which Curiosity now resides, was capable of supporting life as we know it.