Mars' missing carbon dioxide may be buried

Mar 09, 2011
This image from orbit covers an area about 460 meters (about 1,500 feet) across, in which carbonate minerals have been identified from spectrometer observations. Fractures and possible layers are visible in the light-toned rock exposure containing the carbonates. Credit: NASA/JPL-Caltech/Univ. of Arizona

(PhysOrg.com) -- Rocks on Mars dug from far underground by crater-blasting impacts are providing glimpses of one possible way Mars' atmosphere has become much less dense than it used to be.

At several places where cratering has exposed material from depths of about 5 kilometers (3 miles) or more beneath the surface, observations by a mineral-mapping instrument on NASA's Mars Reconnaissance Orbiter indicate carbonate minerals.

These are not the first detections of carbonates on Mars. However, compared to earlier findings, they bear closer resemblance to what some scientists have theorized for decades about the whereabouts of Mars' "missing" carbon. If deeply buried carbonate layers are found to be widespread, they would help answer questions about the disappearance of most of ancient Mars' atmosphere, which is deduced to have been thick and mostly carbon dioxide. The carbon that goes into formation of carbonate minerals can come from atmospheric carbon dioxide.

"We're looking at a pretty lucky location in terms of exposing something that was deep beneath the surface," said planetary scientist James Wray of Cornell University, Ithaca, N.Y., who reported the latest carbonate findings today at the Lunar and Planetary Science Conference near Houston. Huygens crater, a basin 467 kilometers (290 miles) in diameter in the southern highlands of Mars, had already hoisted material from far underground, and then the rim of Huygens, containing the lifted material, was drilled into by a smaller, unnamed cratering event.

Observations in the high-resolution mode of the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter show spectral characteristics of calcium or iron carbonate at this site. Detections of clay minerals in lower-resolution mapping mode by CRISM had prompted closer examination with the spectrometer, and the carbonates are found near the clay minerals. Both types of minerals typically form in wet environments.

This image shows the context for orbital observations of exposed rocks that had been buried an estimated 5 kilometers (3 miles) deep on Mars. Credit: NASA/JPL-Caltech/Univ. of Arizona

The occurrence of this type of carbonate in association with the largest impact features suggests that it was buried by a few kilometers (or miles) of younger rocks, possibly including volcanic flows and fragmented material ejected from other, nearby impacts.

These findings reinforce a report by other researchers five months ago identifying the same types of carbonate and clay minerals from CRISM observation of a site about 1,000 kilometers (600 miles) away. At that site, a meteor impact has exposed rocks from deep underground, inside Leighton crater. In their report of that discovery, Joseph Michalski of the Planetary Science Institute, Tucson, Ariz., and Paul Niles of NASA Johnson Space Center, Houston, proposed that the carbonates at Leighton "might be only a small part of a much more extensive ancient sedimentary record that has been buried by volcanic resurfacing and impact ejecta."

Carbonates found in rocks elsewhere on Mars, from orbit and by NASA's Spirit rover, are rich in magnesium. Those could form from reaction of volcanic deposits with moisture, Wray said. "The broader compositional range we're seeing that includes iron-rich and calcium-rich carbonates couldn't form as easily from just a little bit of water reacting with igneous rocks. Calcium carbonate is what you typically find on Earth's ocean and lake floors."

He said the carbonates at Huygens and Leighton "fit what would be expected from interacting with ancient bodies of water on Mars." Key additional evidence would be to find similar deposits in other regions of Mars. A hunting guide for that search is the CRISM low-resolution mapping, which has covered about three-fourths of the planet and revealed clay-mineral deposits at thousands of locations.

"A dramatic change in atmospheric density remains one of the most intriguing possibilities about early Mars," said Mars Reconnaissance Orbiter Project Scientist Richard Zurek, of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Increasing evidence for liquid water on the surface of ancient for extended periods continues to suggest that the atmosphere used to be much thicker."

Carbon dioxide makes up nearly all of today's Martian air and likely was most of a thicker early atmosphere, too. In today's thin, cold atmosphere, liquid water quickly freezes or boils away.

What became of that carbon dioxide? NASA will launch the and Volatile Evolution Mission (MAVEN) in 2013 to investigate processes that could have stripped the gas from the top of the atmosphere into interplanetary space. Meanwhile, CRISM and other instruments now in orbit continue to look for evidence that some of the in that ancient atmosphere was removed, in the presence of liquid water, by formation of carbonate minerals now buried far beneath the present surface.

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Mike_Bailey
1 / 5 (3) Mar 09, 2011
So. if carbon makes up the sub surface surface of mars, it seems logical to oxidize it into carbon di-oxide by carbon ignition... Carpet-bomb Mars! Then when the carbon re-unites with the minimal oxygen latent in the existing Martian atmosphere, and the dust has settled, it would provide an environment that would support plant life introduction. Remember that the arctic region water Ice would evaporate and dissipate into the resulting swirl of ash and smoke, providing water vapor and then eventual condensation at the habitable zones near but not on the equator. The plants then would have to thrive on iron rich Earth (Marsth?) and be able to produce enough sugars from the minimal sunlight they receive, in order to produce (and re-introduce) O2.

The plan for terraforming Mars by Mike Bailey aka Angus
Wolf358
1 / 5 (1) Mar 09, 2011
I think you'd still want some kind of planetary magnetic field to keep cosmic rays out... Maybe a small nuclear power plant, and a few turns of superconductor cable wrapped around the equator?
Mike_Bailey
1 / 5 (3) Mar 09, 2011
And there you have it! That thought had ocurred to me, the firestorm I described above would have to be a bit more than simple detonated material, it would have to penetrate to a depth of several kilometers and literally churn up the martian sub layers and ignite the resulting exposed carbon layers at the same time. Thinking bunker buster class to the 3rd or 4th power with each detonation. That sort of pounding could have the by product of heating up the core and magma layers (not to mention exposing the shallow areas), possibly re-igniting the furnace that is supposedly responsible for the magnetic fields you spoke of, however that may not work so your idea is very sensible.
Mike_Bailey
1 / 5 (3) Mar 09, 2011
And there you have it! That thought had ocurred to me, the firestorm I described above would have to be a bit more than simple detonated material, it would have to penetrate to a depth of several kilometers and literally churn up the martian sub layers and ignite the resulting exposed carbon layers at the same time. Thinking bunker buster class to the 3rd or 4th power with each detonation. That sort of pounding could have the by product of heating up the core and magma layers (not to mention exposing the shallow areas), possibly re-igniting the furnace that is supposedly responsible for the magnetic fields in the first place, however that may not work so your idea is very sensible.

Ramael
3 / 5 (1) Mar 09, 2011
Couple problems, your biggest is that plants breathe oxygen, co2 of a by product of photosynthesis, but they this use that energy through cellular respiration. Why do you think forests get smokey at night, a thin layer of co2 forms on the ground from all the stationary respiration.

Plus you still have the problem with the temperature on mars, which rises and drops sparatically, and lets not forget, its farther from the sun than we are, and its core is practically cold.

barakn
5 / 5 (1) Mar 10, 2011
Mike - your use of the words "oxidize" and "ignite" suggests you think the carbonate is somehow going to burn, something that's not going to happen in an atmosphere devoid of O2, and especially since the carbon in the carbonate is as about as oxidized as it can get. The only kind of "carpet bombing" that would work would be with nuclear bombs. They'd heat the carbonate, releasing CO2 and leaving behind calcium oxide (a.k.a. quicklime) and magnesium oxide. Subsequent precipitation would hydrate these, forming caustic lakes. Volcanic ash and other atmospheric grit would fall in, and eventually the lakes would solidify into a radioactive concrete that would slowly absorb the CO2 back into itself. Brilliant. Just brilliant.
jmlvu
not rated yet Mar 10, 2011
Why not redirect a few comets or a planetoid to do the terra forming for you?
Terrible_Bohr
5 / 5 (1) Mar 10, 2011
Let's stick to searching for signs of past life on Mars before we go about potentially destroying the evidence.
GaryB
not rated yet Mar 13, 2011
You can either terraform a planet over 10,000 years, 100,000 asteroids, nuclear bombs etc ... or just spend about 50 years and a couple thousand bucks creating organisms that are adapted to the planet.