First signs of boron on Mars hint at past groundwater, habitability

SAN FRANCISCO — Another element has been found in Mars’ chemical arsenal. While sampling rocks from the Gale crater, the Curiosity rover detected boron concentrations of about 10 to 100 parts per billion. It’s the first find of boron on the Red Planet and hints that the Martian subsurface may have once been habitable for microbes, scientists reported December 13 at the American Geophysical Union’s fall meeting.

The boron was discovered in veins of calcium sulfate. Such features on Earth indicate that nonacidic groundwater with a temperature of around zero to 60° Celsius once flowed through the area — conditions favorable to microbial life. As groundwater evaporates, boron and calcium sulfate are left behind. How this process unfolded on Mars is uncertain; researchers expect more clues to be uncovered as Curiosity continues its trek (SN: 5/2/15, p. 24).