Test results from NASA's Curiosity rover's drilling and chemical analysis of Martian rock show that the Red Planet could have supported life as we know it.
"A fundamental question for this mission is whether Mars could have supported a habitable environment," said Michael Meyer, lead scientist for NASA's Mars Exploration Program in a statement. "From what we know now, the answer is yes."
At a Tuesday press conference in Washington NASA scientists explained that the rock sample, taken from Yellowknife Bay near Mount Sharp, contains all the elements needed for microbial life, including sulfur, nitrogen, hydrogen, oxygen, phosphorus, and carbon. It has taken Curiosity seven months and six days since landing to achieve one of its primary missions.
The sample was 20 per cent clay and contained water-rounded stones, indicating that the spot was once covered either permanently or regularly by water. John Grotzinger, Mars Science Laboratory project scientist, said the water would have been neutral, or maybe slightly alkaline, and possibly safe to drink.
"We have characterized a very ancient, but strangely new 'gray Mars' where conditions once were favorable for life," he explained.
The sample also contained a mixture of oxidized, less-oxidized, and even non-oxidized chemicals such as those used by microbes to live on Earth, but NASA is not even close to making the call that Martian microbes are or even were alive, he said. Nevertheless, the test results showed that water had been present, and in conditions suitable for both organic and possible inorganic life, such as silicon-based organisms.
"This is only definitively habitable environment we've ever described and recorded," said David Blake, principal investigator for the Chemistry and Mineralogy (CheMin) instrument at NASA's Ames Research Center. "There are other places we could suggest but we haven't measured there."
The CheMin and Sample Analysis at Mars (SAM) instruments on Curiosity are responsible for the readings, and SAM's principal investigator Paul Mahaffy explained that the processing of the data was still turning up intriguing possibilities.
"We got really excited about seeing a CO2 spike," he said, "but we're still deconvoluting the spectrograph information. There's what look like nitrogen compounds in there and a fair bit of hydrogen chloride, showing chlorine not only as chloromethane but also as hydrochloric acid."
Grotzinger explained that NASA still had a "long row to hoe" before it could look for organic life itself, however. Curiosity will have to drill more sample to make sure the rock drilled isn't a meteorite – although the possibility is slight, since the sample is sedimentary rather than igneous, he said.
Curiosity will then have to test if the chemicals and compounds found are naturally occurring or if they have been produced by inorganic life, he said, which would require more sampling. Only when this data has been cleared can Curiosity begin to analyze it for signs of organics.
"This is a huge scientific question: did Mars have a habitable environment? And now we have an answer," said John Grunsfeld, former astronaut and now associate administrator of NASA's Science Mission Directorate. "We now have the food to imagine a very different Mars from modern times; it makes me want to go there." ®