Organic carbon on Mars comes from natural "batteries"

For years, astronomers have wondered where the red planet gets its organic carbon compounds, associated with life as we know it on Earth. Organic carbon often comes from biological sources on Earth, but researchers strive to understand how they are created on Mars. Now, a new analysis of Martian meteorites indicates that organic carbon on Mars could come from natural "batteries".

By analyzing three meteorites that have fallen on Earth since March, a research team led by Andrew Steele of the Carnegie Institution for Science found that meteorites contain organic carbon similar to that detected on Mars by NASA's Curiosity robot. This allowed Steele and his team to study and reveal how organic carbon compounds are synthesized on Mars.

Martian batteries

The team found that the compounds were probably due to electrochemical corrosion of Martian minerals by salty liquid brine. This process works like a natural "battery" fueled by corrosion, providing energy to the reactions that create the compounds, Steele said in a press release.

This work stems from research conducted in 2012, during which Steele and his team confirmed that the organic carbon from these meteorites actually came from Mars and not from any terrestrial contamination. They also found that carbon did not come from a biological source. The purpose of this new work was to determine the source of carbon if it was not created by life.

"Revealing the processes by which organic carbon compounds form on Mars has been a subject of great interest to understand its livability potential," Steele said.

"The reactions that occur are probably very similar to those of the early Earth," he adds. In fact, wherever igneous rocks are surrounded by salty brines, such as in the Europa and Enceladus submarine oceans, this process could occur.