NASA's Curiosity rover has found what it was looking for in its very first taste of Martian rock – much to everyone's surprise. The scoop of grey powder contains definitive evidence that the Red Planet was once suited to life. All the signs are that Mars had plentiful, slightly salty water that could have supported primitive microbes.
The hope is that Mars can help us understand the origins of life – even if the planet's early transformation into a cold, dry, hostile world meant life never got started there.
Determining the habitability of Mars was Curiosity's chief goal when it landed in Gale crater in August 2012. But the rover was expected to hit pay dirt months from now, when it reached a 5-kilometre-high mound of layered sediments in the middle of the crater. Instead, it struck lucky with a sample of rock drilled on 9 February in an area called Yellowknife Bay, near what was probably an ancient streambed.
According to Curiosity's on-board chemistry lab, the sample is between 20 and 30 per cent smectite, a clay mineral that forms in the presence of water. The instruments also detected minerals indicating that this water was pH neutral and carried substances capable of supplying microbes with energy.
"We have found a habitable environment that is so benign and supportive of life that probably if this water had been around and you had been on the planet, you would have been able to drink it," says rover project scientist John Grotzinger.
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