

The watering hole near the Martian equator existed about 3.5 billion years ago, around the time when life evolved on Earth. Scientists say the Martian lake was neither salty nor acidic and contained life-friendly nutrients.

"This just looks like a pretty darn ordinary Earthlike lake in terms of its chemistry," said project scientist John Grotzinger of the California Institute of Technology. "If you were desperate, you could have a drink of this stuff."

The lake, about the size of a small Finger Lake in upstate New York, likely was around for tens of thousands - perhaps hundreds of thousands - of years. Even when the lake dried up, scientists said, microbes could have migrated underground and existed for potentially tens of millions of years.

It's not known whether simple life forms ever took hold on Mars, and Curiosity lacks the tools to search for any fossilized microbes. It can only analyze the chemical makeup of rocks and soil.


"The new results definitely reinforce the idea that past life on Mars was possible," planetary scientist David Paige at the University of California-Los Angeles said by e-mail.



Early in its history, Mars was more tropical, with streams and rivers. With water plentiful, scientists believe, it was a place where primitive life could have thrived by feeding on rocks and minerals similar to tiny organisms on Earth that hide in caves and underwater vents.



Analyzing a sedimentary rock known as a mudstone, the nuclear-powered rover found further evidence of favorable environmental conditions - an ancient lake that was theoretically drinkable, harboring some of the key ingredients for life including carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus.