Curiosity Asks: Where Are the Mars Organics?
Curiosity inspects the drill hole with its robotic arm-mounted Mars Hand Lens Imager (MAHLI) camera.
Organic carbon, even if it didn’t come from life, should be all over Mars, which, like Earth, is believed to have been pummeled by organic-rich comets and asteroids early in its history.
The destructive effects of ultraviolet and cosmic radiation, combined with what appears to be a ubiquitous layer of organic-consuming chemicals produced by so-called perchlorates on the surface of Mars, have driven the quest for organics underground. Inside rocks may be evidence of a different, organic-friendlier time in the planet’s history.
On Tuesday, scientists with NASA’s Mars Curiosity rover mission are due to report the first chemical analysis of powder drilled out from inside a rock at the Gale Crater landing site.
Scientists already know that the inside of the target rock is not as oxidized as its exterior.
The powder was delivered into a sampling scoop and photographed before being processed by two onboard laboratory instruments. The powder appeared gray, while the rock’s surface, like most of Mars, is red due to oxidized iron, or rust, that is globally distributed by the planet’s winds.
“The oxidation layer at least here is pretty thin, so that is encouraging,” NASA’s Mars exploration lead scientist Michael Meyer said at a Feb. 27 Mars program planning group meeting.
Curiosity touched down on Aug. 6 inside a 93-mile wide impact crater located near the planet’s equator. Scientists were drawn to a three-mile high mound of what appears to be layered sediments as a place to assess if the planet most like Earth has or ever had the ingredients to support and preserve life.
The building blocks for life, at least life as we know it, includes water, an energy source and organics.
Curiosity’s first science target was not Mount Sharp, which rises from the center of Gale Crater, but a region in the opposite direction originally named Gleneg and later referred to as Yellowknife Bay.
Images and analysis from Mars orbiters show the area has three different types of terrain and that it has a low elevation.
“If water flows downhill on Mars, then this may be where it could have ponded,” Meyers said.
The rover's Mars Hand Lens Imager (MAHLI) camera recorded this close-up view of the drill test results during the 180th Martian day, or sol, of the rover's work on Mars. NASA/JPL-Caltech
Curiosity used its precision drill, the first instrument of its type sent to another planet, to core two small holes in a particularly interesting looking rock named John Klein. The first drilling was a test run, but the second produced a tablespoon of powder that was fed into the rover’s Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM) instruments for analysis.
Four results were radioed back to ground controllers before a computer glitch suspended science operations last week.
The John Klein rock appears to be shot through with veins of minerals that are deposited by flowing water.
“There’s definitely evidence that water has been at work here,” said geochemist and Mars exploration planning group chairman David Des Marais, with NASA’s Ames Research Center in Moffett Field, Calif.
“The geochemical consequences are yet to be determined,” he added.
“One of the of the nice things about this landing site is the low elevation. If there ever was a crater lake on Mars, it should have been in Gale, so I think in that sense we’re on to something here,” Des Marais said.
With ample evidence of past surface water on Mars, scientists hope to answer a far more taxing questions about organics.
“Organics on Mars should be there even if there is no life from meteorites,” geochemist Samuel Kounaves with Tufts University in Medford, Mass., told Discovery News.
Like most scientists Kounaves suspects the surface of Mars is devoid of organics due to radiation and perchlorates, but the question of what lies beyond is only beginning to be answered.
“If you dig inside a rock, or if you dig down far enough, or back in time far enough, there may not have been enough perchlorates or exposure to ultraviolet light to cause these reactions (that destroy organics) so going deep in rocks or deep underground there’s a good chance that organics may have survived there,” Kounaves said.
“The big puzzle has been are we not finding organics because the instruments can’t detect them, or we not finding them because they really aren’t there?” he said.
“It’s possible Mars 2 billion years ago had less oxidizing properties and organics were surviving and they got buried and they’re inside the rock right there waiting for us,” Kounaves said.
A press conference to discuss Curiosity’s first drill sample results begins at 1 p.m. EDT Tuesday.