Rover Finds "Bulletproof" Evidence of Water on Early Mars
Mineral vein "screams water"—and hints at conditions favorable to life.
The find is a vein of gypsum—a mineral that forms in the presence of liquid water—that's been nicknamed Homestake.
The mineral vein is "about as wide as your thumb and a few tens of centimeters long," Cornell University geologist Steve Squyres said yesterday at a meeting of the American Geophysical Union in San Francisco.
Opportunity has found water-related minerals on Mars before, but those discoveries were in sandstones. Before consolidating into rock, the stones' grains might have blown many miles from their sources, obscuring the history of the minerals.
(Related: "Mars Has Liquid Water Close to Surface, Study Hints.")
By contrast, the Homestake vein lies in bedrock, which means "this stuff formed right here," said Squyres, who is the