Rover finds conditions once suited life on Mars
NASA says analysis of rock samples from Mars has shown that the red planet would once have been capable of supporting life.
Analysis of Mars rocks by the Curiosity rover uncovered the building blocks of life - hydrogen, carbon and oxygen - and evidence the planet could once have supported organisms, NASA said.
"A fundamental question for this mission is whether Mars could have supported a habitable environment," Michael Meyer, lead scientist for NASA's Mars Exploration Program said.
"From what we know now, the answer is yes."
At a televised press conference, the NASA team said this was the first definitive proof a life-supporting environment had existed beyond Earth.
"There are places we've suggested could be habitable, but we haven't measured there," Dave Blake, principal investigator for Curiosity's Chemistry and Mineralogy investigation, said.
Curiosity, a six-wheeled robot with 10 scientific instruments on board, is the most sophisticated vehicle ever sent to another planet.
The sample was drilled from sedimentary bedrock in an area which previous research had shown to be an ancient river system or lake bed.
It was found to contain clay minerals, sulfate minerals and other chemicals.
Based on the analysis of those chemicals, researchers were able to determine that the water in which the rocks were formed was of a relatively neutral pH - not overly salty, acidic, or oxidising.
"We have found a habitable environment that is so benign and supportive of life, that probably if this water was around and you had been there, you would have been able to drink it," John Grotzinger, the principal investigator for the Rover mission, said.
Mr Grotzinger described an ancient lake bed where NASA's Curiosity rover collected its first sample.
"The lake bed was filled by sediment, derived from streams," he said.
"But we don't know how long-lived it was. And so that's always a challenge we've got on Mars. It's not like the rocks come with numbers on them that tell you how long the water was there or how much there was there ultimately.
"I think what can do now, with the issue of habitability in the bag [is] we can undertake a more systematic search for a brighter carbon signal.
Speaking at the same press conference, one of NASA's top officials, John Grunsfeld, said the discovery made him "feel giddy".
He said the new data helps add to the picture of what the red planet may have looked in a previous era, with a possible freshwater lake and a snow-capped Mount Sharp.
But it would not have looked like that any time recently, the researchers cautioned.
Although it is hard to confirm an exact date, it was probably at least 3 billion years ago, Mr Grotzinger said.
Researchers also noted that future rock samples will be needed to confirm these results, because it is possible that residual carbon on the drill affected the analysis.
But "the instrument is working beautifully," Paul Mahaffy, principal investigator for Curiosity's Sample Analysis at Mars investigation, enthused.
The team is already planning out where and when to take the next rock samples, as well as planning out the rover's route to nearby Mount Sharp, where mineral analysis should help with dating calculations.
The $US2.5 billion nuclear-powered Curiosity has been exploring the planet's surface since its dramatic landing on August 6, for an anticipated two-year mission.
Scientists do not expect Curiosity to find aliens or living creatures - and indeed, they said Tuesday, the rover does not have the capability to identify microbial life or fossils, even if they were present today.
But the analysis of soil and rocks is aimed at finding evidence Mars may have supported life in the past.
- Photo: An artist's impression of the Mars Science Laboratory, aka Curiosity, part of NASA's Mars Exploration Program. (jpl.nasa.gov)
- Photo: A NASA graphic shows what the sky crane landing system will look like when Curiosity is lowered onto the Martian surface. (NASA)
- Photo: A graphic shows NASA's Curiosity rover inspect a rock on Mars. (NASA)
- Photo: The shadow of the Mars Curiosity Rover is seen on the surface of the planet soon after landing on August 6, 2012. (NASA)
- Photo: This image taken by NASA's Curiosity shows what lies ahead for the rover -- its main science target, Mount Sharp. The rover's shadow can be seen in the foreground, and the dark bands beyond are dunes. Rising up in the distance is the highest peak Mount Sharp at a height of about 3.4 miles, taller than Mt. Whitney in California. The Curiosity team hopes to drive the rover to the mountain to investigate its lower layers, which scientists think hold clues to past environmental change. (NASA/JPL-Caltech )
- Photo: A NASA image showing the projected landing site for the Curiosity rover circled, near the foot of Mount Sharp in the Gale crater on Mars. (NASA)
- Photo: Tracks left by NASA's Curiosity rover as it completed its first test drive on Mars, August 22, 2012. The rover went forward 4.5 metres, rotated 120 degrees and then reversed 2.5 metres. Curiosity is now 6 metres from its landing site, named Bradbury Landing. (NASA/JPL-Caltech)
- Photo: An image taken by NASA's Mars Rover showing the base of Mount Sharp, the rover's eventual destination. (NASA/JPL-Caltech/MSSS)