The group of scientists working with NASA's Curiosity rover made a big announcement during a press conference today: "We have found a habitable environment that is so benign" if there was water there, "you be able to drink it," John P. Grotzinger, professor of geology at Caltech, said summing up the rover's latest findings.

That is, at one point Mars had the right conditions to support living microbes.

Scientists came to this conclusion after the rover drilled into a sedimentary rock near an ancient stream bed and found sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon — key ingredients for life.

NASA's Jet Propulsion Laboratory explains in a press release:

"Scientists were surprised to find a mixture of oxidized, less-oxidized, and even non-oxidized chemicals, providing an energy gradient of the sort many microbes on Earth exploit to live. This partial oxidation was first hinted at when the drill cuttings were revealed to be gray rather than red.

"'The range of chemical ingredients we have identified in the sample is impressive, and it suggests pairings such as sulfates and sulfides that indicate a possible chemical energy source for micro-organisms,' said Paul Mahaffy, principal investigator of the SAM suite of instruments at NASA's Goddard Space Flight Center in Greenbelt, Md."

One of the more controversial questions asked during the press conference was whether Earth and Mars may have been habitable at the same time. The scientists said they couldn't answer that question, yet.

But this is big news Michael Mayer, lead scientists for NASA's Mars Exploration Program, said in a statement.

"A fundamental question for this mission is whether Mars could have supported a habitable environment," he said. "From what we know now, the answer is yes."

Update at 2:35 p.m. ET. 'Achievement Unlocked':

Here's how Curiosity Rover broke the news on Twitter:

"I was sent to Mars to find evidence of past habitable environments. Achievement unlocked!"

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Source: NPR