Mars was capable of supporting microbial life in the distant past, scientists announced today.
They reached this conclusion after studying the latest observations from NASA's Curiosity rover, which just analyzed the first-ever sample collected from the interior of a Red Planet rock.
Here are answers to a few basic questions about Curiosity's discovery, and what it means about the Red Planet's past and the rover's future.
What exactly did Curiosity find?
Last month, Curiosity drilled 2.5 inches (6.4 centimeters) into a rock on a Martian outcrop that mission scientists have dubbed "John Klein." [The Search for Life on Mars (Photo Timeline)]
The rover's onboard Chemistry & Mineralogy (CheMin) and Sample Analysis at Mars (SAM) instruments found some of the chemical ingredients for life in the collected powder, including sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon. The mix of compounds also suggests that the area may have contained chemical energy sources for potential Red Planet microbes, researchers said.
In addition, the sample contains clay minerals, indicating that the rock was exposed to a benign aqueous environment — such as a neutral-pH lake, for example — billions of years ago.
To be clear, Curiosity found no evidence that life has ever existed on the Red Planet. But its results suggest that the John Klein site could have supported microbes long ago, if they ever evolved on Mars or were transported there.
So what? Didn't we already know that ancient Mars was wet?
Scientists have known for years that water flowed or pooled on the surface of Mars in the ancient past. But there's more to habitability than the mere existence of liquid water.
For primitive microbial life to survive, a site must also have the right chemical makeup and a potential energy source, researchers say. And all of these ingredients were apparently present at John Klein.
Doesn't the right chemical makeup include organic compounds? Did Curiosity find any of those?
The SAM instrument can detect complex organics — the carbon-containing building blocks of life as we know it — and Curiosity is looking for these molecules on Mars, but it hasn't found anything conclusive yet.
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