ASU: Instrument helps identify rare rock on Mars

[bystander]

Instrument helps identify rare rock on Mars
Arizona State University - 03 June 2010

It's amazing what cleaning your glasses can reveal. A mineral-scouting instrument developed at ASU's Mars Space Flight Facility has found an outcrop of rock rich in carbonate minerals in the Columbia Hills of Gusev Crater on Mars, according to a report published online June 3 in the journal Science. The instrument is onboard NASA's Mars Exploration Rover Spirit.

What makes the discovery unusual is that Spirit visited the outcrop, dubbed Comanche, back in December 2005. Yet the data pointing to the discovery languished since then because one of the instruments that detected the carbonate minerals was partly blinded by dust.

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PIA13175: Carbonate-Containing Martian Rocks

More than four years after Mars rover Spirit visited the Comanche outcrop in Gusev Crater's Columbia Hills, scientists armed with a new instrument calibration have discovered the rocks are rich in long-sought carbonate minerals. Comanche (left) and Comanche Spur (right) appear reddish-brown in this false-color image from Spirit's Pancam. (The bluish-wite rocks in the foreground belong to an unrelated outcrop.)

(Credit: NASA/JPL-Caltech/Cornell University)

NASA Rover Finds Clue to Mars' Past and Environment for Life
NASA JPL MER (2010-189) - 03 June 2010

Rocks examined by NASA's Spirit Mars Rover hold evidence of a wet, non-acidic ancient environment that may have been favorable for life. Confirming this mineral clue took four years of analysis by several scientists.

An outcrop that Spirit examined in late 2005 revealed high concentrations of carbonate, which originates in wet, near-neutral conditions, but dissolves in acid. The ancient water indicated by this find was not acidic.

NASA's rovers have found other evidence of formerly wet Martian environments. However the data for those environments indicate conditions that may have been acidic. In other cases, the conditions were definitely acidic, and therefore less favorable as habitats for life.

Laboratory tests helped confirm the carbonate identification.The findings were published online Thursday, June 3 by the journal Science.

"This is one of the most significant findings by the rovers," said Steve Squyres of Cornell University in Ithaca, N.Y. Squyres is principal investigator for the Mars twin rovers, Spirit and Opportunity, and a co-author of the new report. "A substantial carbonate deposit in a Mars outcrop tells us that conditions that could have been quite favorable for life were present at one time in that place. "

Identification of Carbonate-Rich Outcrops on Mars by the Spirit Rover

• Science Express, 03 June 2010, DOI: 10.1126/science.1189667

Water Spirit: Rover Findings Hint of a Warmer, Wetter Era on Mars
Scientific American - 03 June 2010

Bountiful carbonate minerals in a rock outcrop on the Red Planet could have formed under watery greenhouse conditions billions of years ago

For NASA's Spirit rover, the days of roaming the Red Planet may now be in the past, but the observations the wheeled bot made in its travels are still paying scientific dividends. A new analysis of geologic data gathered by the rover nearly five years ago finds that a rock outcrop on Mars is rich in carbonates, which are minerals that form readily in watery, carbon-rich environments. According to the study, the finding lends more credence to the hypothesis that Mars may have once had a wetter, warmer climate thanks to a dense carbon dioxide atmosphere. What is more, the aqueous processes implicated in the carbonate formation point to a neutral environment more hospitable to life than the acidic waters thought to have existed elsewhere on Mars.

Multiple lines of evidence point to past flows of water across the Martian surface, but conditions on the planet now preclude the existence of liquid water. In the past Mars's surface could have been much warmer, particularly if a robust atmosphere had provided a significant greenhouse effect on the planet. The dense carbon dioxide atmosphere often invoked to explain the warm era should have left its mark on the planet's geology, as carbon and oxygen sequestered in carbonate minerals. But prior to the new study, carbonates had only been found in small amounts on Mars, creating an evidentiary problem for the carbon dioxide hypothesis.

In January NASA declared Spirit a stationary science platform after months of efforts to free the rover from a patch of soft soil came up short. But in late 2005, when the rover was still mobile, it had investigated a group of rock outcrops in a region of Gusev Crater known as the Columbia Hills. Equipped with a rock-abrasion tool and a suite of spectrometers, the robotic geologist poked around the formation known as the Comanche outcrops, but its findings were not conclusive at the time. Now, however, evidence from Spirit's three spectrometers points to a large carbonate component in Comanche, according to the study published online June 3 by Science.

Mars rover finds conditions 'more conducive to life'
Nature News - 03 June 2010

Carbonate-rock outcrop holds clues to red planet's history.

More than four years after they were gathered, hard-to-interpret data from the Mars rover Spirit have finally been cracked. They reveal carbonate minerals to be a major component of a rock formation known as Comanche in the Columbia Hills region of the Gusev Crater.

"The discovery is significant," says Oded Aharonson, a planetary scientist at the California Institute of Technology in Pasadena who was not directly involved in the find, "because of the intimate connection between the formation of carbonates and persistent liquid water." That connection helps to solidify the view that Mars was once warm, wet and perhaps capable of supporting life.

One way for the planet to have been warm in its youth would have been greenhouse warming from a thick carbon dioxide atmosphere, but, if so, where did all the carbon dioxide go? "One possibility is that meteorites blew it out into space," says Richard Morris, a planetary scientist at NASA's Johnson Space Center in Houston, Texas, and lead author of the study1. "Another is that it got tied up interacting with water and precipitated out as carbonate minerals."

Because carbonate minerals dissolve easily in acid, their continued, unaltered existence also indicates that they not only formed in chemically neutral — rather than acidic — conditions, but that the conditions remained that way. That was not the case for other water-related rocks found on the far side of the planet by the rover Opportunity2. "That's certainly more conducive to life," says Morris, "but it doesn't prove one way or another that there was life."

[bystander]

Big hunks of carbonate rock on Mars at last
Planetary Society Blog - 10 June 2010

Carbonate rocks should be all over Mars. Mars' atmosphere is mostly carbon dioxide, and there is clear evidence for past water acting to modify its surface. If you have liquid water under an atmosphere of carbon dioxide it's actually kind of hard, chemically speaking, not to make carbonate rocks.

But it's been hard to find carbonates, surprisingly so. It's not that they're totally absent; they make up a couple of percent of the weight of Martian meteorites (usually found as crystals precipitated within fractures within the rock). And there's one spot on Mars, Nili Fossae, where spectroscopists are pretty sure that carbonate minerals crop out at the surface, but they can't tell how much of the rock the carbonates make up there. But we should really see carbonate as a major component of substantial quantities of Martian rock, and we just don't.

So it was pretty significant last week when a team of geologists working with Mars Exploration Rover Spirit data announced that Spirit had touched a rock that contained substantial amounts of carbonate minerals, 16 to 34 percent by weight. The first author of the paper, published in Science Express, was Richard Morris, but I exchanged emails with the paper's second author, Steve Ruff.

The rock was named "Comanche," and Spirit encountered it as she was descending from the summit of Husband Hill around sol 700, in December 2005. That was a long time ago, back when Spirit was still a mountain-climbing rover!

Martian soda water, on the rocks
Bad Astronomy - 10 June 2010

Wow, that’s like three puns in one title.

Anyway, scientists have revealed they have found large amounts of carbonates (minerals containing CO3 in them) in rocks on Mars. That’s kind of a big deal: it’s been expected that a lot of rocks would have this compound in them, because there’s lots of carbon dioxide afoot there, and plenty of evidence that Mars was once wet. Those two ingredients lead to carbonates. Yet the rocks looked at closely by the rovers have been strangely devoid of them.

For the rover Opportunity it’s not all that strange; the water on that part of Mars was acidic, and that makes carbonates tough to form. But Spirit is on the other side of the planet, and it was expected it would find carbonates all over the place. Well, turns out it finally has. Some rocks it examined back in 2005 are loaded with carbonates, but it took this long to figure that out because dust that got in the instrument on the rover screwed things up. The scientists had to do some heroic work to tease the data out.

At this point we’ve pretty much exhausted my knowledge of this, but happily we have access to Emily Lakdawalla and her blog, where she goes into detail about the rocks, talking to a scientist involved in all this, too. So go over there and get the rest of this interesting story.

And when you’re over there, don’t forget: we’re talking about a whole planet here. A world. And it was once warmer, wetter, with a thicker atmosphere. Sure, it was over a billion years ago, but it’s always a good idea to keep an eye on Mars when thinking about Earth. There but for the grace of random chance go us.