Analysis of Martian soil by NASA’s ongoing Mars Curiosity rover turned up a surprising amount of water, as well as a chemical that will make a search for life more complicated, scientists said on Thursday.
A scoop of fine-grained sand collected by the rover shortly after its August last year touchdown showed the soil contains about 2 percent water by weight.
“It was kind of a surprise to us,” Curiosity scientist Laurie Leshin of the Rensselaer Polytechnic Institute said.
“If you take a cubic foot [.09m2] of that soil you can basically get two pints [946ml] of water out it,” she said. “The soil on the surface is really a little like a sponge for sucking stuff out of the atmosphere.”
Scientists announced last week that so far the planet’s atmosphere shows no signs of methane, a gas which on Earth is strongly tied to life. Plumes of methane had been detected over the past decade by Mars orbiters and ground-based telescopes.
Methane, which should last about 200 years under Martian photochemistry, can also be produced by geologic events.
The water was found by heating a tiny bit of soil to 835°C inside Curiosity’s chemistry laboratory and analyzing the resulting gas releases.
Scientists found that in addition to water, sulfur dioxide, carbon dioxide and other materials, the sands of Mars also contain reactive chemicals known as perchlorates.
NASA’s now-defunct Phoenix lander had found perchlorate in the planet’s northern polar region, but scientists did not know until Curiosity’s analysis that the chemical is apparently widespread.
“They seem to accumulate on the surface [of Mars], almost like snow,” Curiosity lead scientist John Grotzinger with the California Institute of Technology said.
That is crucial to know because looking for organic material on Mars may require a new approach.
“The tried-and-true technique on Earth is to heat the sample and take a look at the gases that are produced,” Grotzinger said.
However, the heat can cause perchlorate to break down, in the process degrading the organic compounds scientists are looking for, Grotzinger said.
The presence of perchlorate in soil samples could explain why scientists have had a hard time finding organic material on Mars. They believe that even if life never evolved on Mars, the planet should have organic carbon deposits left by crashing asteroids and meteors.