NASA's Curiosity rover finds clues for Mars' missing carbonate

LOS ANGELES, April 18 (Xinhua) -- NASA's Curiosity rover has uncovered a hidden chemical archive of ancient Mars' atmosphere, which suggests that large amounts of carbon dioxide have been locked into the crust of the Red Planet, according to a new study published Friday.

Researchers have long believed that Mars once had a thick, carbon dioxide-rich atmosphere and liquid water on the planet's surface. That carbon dioxide and water should have reacted with Martian rocks to create carbonate minerals. But rover missions and near-infrared spectroscopy analysis from Mars-orbiting satellites have not yet found the amounts of carbonate on the planet's surface predicted by this theory.

Data from three of Curiosity rover's drill sites revealed the presence of siderite, an iron carbonate mineral, within the sulfate-rich rocky layers of Mount Sharp in Mars' Gale Crater, according to the study published in the Science journal.

"The discovery of abundant siderite in Gale Crater represents both a surprising and important breakthrough in our understanding of the geologic and atmospheric evolution of Mars," said Benjamin Tutolo, associate professor at the University of Calgary, Canada, and lead author of the paper.

The discovery of this carbonate mineral in rocks beneath the Martian surface suggests that carbonate may be masked by other minerals in near-infrared satellite analysis, according to NASA. ■