A NASA’s orbiting spacecraft has discovered the mineral evidence for a water environment capable of supporting life on Mars, according to media reports Friday.
Deposits of the 3.6 billion-year-old carbonate were spotted in the bedrock at the edge of a 930-mile-wide (1,490-km-wide) crater. The deposits are about the size of football fields and are visible in images taken by the Mars Reconnaissance Orbiter.
It is the first time scientists have found a site where carbonate formed.
"Obviously this is very exciting," said John Mustard of Brown University in Rhode Island. "It's white -- it's a bulbous, crusty material."
Carbonate is formed in neutral or alkaline water. It dissolves quickly in acid, so its discovery counters the theory that all water on Mars was at one time acidic.
The region "would have really been a clement, benign environment for early Martian life," said Bethany Ehlmann of Brown University.
Carbonate previously had been found in minuscule amounts in soil samples provided by the Phoenix Mars Lander, Martian dust and Martian meteorites on Earth.