Curiosity rover uncovers evidence of a past lake on Mars that
had the kind of chemicals that could have supported life.
"Is this the smoking gun that says there was life on Mars? No,"
says NASA soil mineralogist Douglas Ming, who took part in the
new research. "Is this a smoking gun that this was a habitable
environment? There's pretty good evidence for that. We have an
environment that is very much … like on Earth."  Despite the
difficulties of finding evidence of past life on Mars, "I've
always been an optimist that we will find it someday," says
astrobiologist Clark Johnson of the University of Wisconsin-
Madison, who was not involved with the study. "This is a
wonderful step forward."  After its triumphant arrival on the
Red Planet in August 2012, Curiosity trundled only a quarter-
mile from its landing spot to a tantalizing depression named
Yellowknife Bay. There it didn't take long for the rover's
instruments to reveal an expanse of thick, fine-grained rock,
the footprint of an ancient lake. Tests sho