Category Archives: mars climate

jet Propulsion Laboratory, Mars, mars climate, Mars Reconnaissance Orbiter, NASA

Mars Missing Carbon Dioxide May Not Be Missing

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It Might Just Be Buried

This image shows the context for orbital observations of exposed rocks that had been buried an estimated 5 kilometers (3 miles) deep on Mars. It covers an area about 560 kilometers (350 miles) across, dominated by the Huygens crater, which is about the size of Wisconsin. The impact that excavated Huygens lifted material from far underground and piled some of it in the crater's rim. At about the 10 o'clock position around the rim of Huygens lies an unnamed crater about 35 kilometers (22 miles) in diameter that has punched into the uplifted rim material and exposed rocks containing carbonate minerals. The minerals were identified by observations with the Compact Reconnaissance Imaging Spectrometer for Mars on NASA's Mars Reconnaissance Orbiter. North is toward the top of this image, which is centered at 14 degrees south latitude, 304.4 degrees west longitude. The image combines topographical information from the Mars Orbiter Laser Altimeter instrument on NASA's Mars Global Surveyor with daytime infrared imaging by the Thermal Emission Imaging System camera on NASA's Mars Odyssey orbiter. Image credit: NASA/JPL-Caltech/Arizona State Univ. Click to enlarge.

I am a long-time Mars junkie. When I was growing up, I used to play at exploring Mars, and I probably expected to be living on the Red Planet some day.  Childhood dreams are like that — and the reality they lead to is a far different place.

For example, my “play” Mars looked a lot like Earth. Oh, the sky was red (I figured it had to have a red atmosphere).  It had red trees and red monsters and red food.  But, it never occurred to me that I wouldn’t be able to stand on its surface and breathe the air.  That’s a lesson I had to wait to learn when I grew up and studied the results of ongoing Mars missions. That was when I found out that Mars doesn’t have air like we do here on Earth. it’s got a carbon dioxide (CO2) atmosphere. A thin one, at that.  But, scientists suspect that the Red Planet used to have MORE atmosphere.

One of the recurring questions about Mars is the location of all its carbon dioxide. The Red Planet has a cold, thin, carbon-dioxide-rich atmosphere. Liquid water quicky boils away in that environment.

CO2 can get squirreled away in rocks, so-called carbonate minerals or carbonate layers. If they’re underground (under the surface), then that material isn’t easily found — unless you can dig it up and study it.

Essentially, that’s what planetary scientists using the Mars Reconnaissance Orbiter (MRO) have done. Oh, they haven’t used the orbiter to dig underground. They used it as it orbited above the surface to study rocks that have been dug up for us — by cratering events. Such an event was reported on at a meeting of planetary scientists this week.

The target studied was in Huygens crater, a basin 467 kilometers (290 miles) in diameter in the southern highlands of Mar. There are actually two cratering events in the area.  When Huygens was dug out by an incoming impactor, that action hoisted material from far underground. Then, the rim of Huygens, containing the earlier lifted material, was drilled into by a smaller, unnamed cratering event.

The occurrence 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.

So, how does an impact dredge up rocks that show us what Mars was like in the past? When a meteor blasts into the surface of Mars (or any surface), it sends material flying away from the impact zone. That uncovers buried rocks. The MRO has an instrument that can study the chemical makeup of those rocks that have been uncovered.

At several places on Mars where cratering has exposed material from depths of about five kilometers (three miles) or more beneath the surface, MRO’s instrument has found evidence of carbonate minerals. This isn’t the first time carbonates have been found, but the finding does seem to confirm the speculated-on whereabouts of the missing Mars carbon.  And, if there are deeply buried carbonate layers are widespread on Mars, that would go a  long ways toward explaining what happened to the early Martian atmosphere, whihc was likely a much thicker carbon dioxide layer than we see on the Red Planet today.  In essence, the carbon that goes into formation of carbonate minerals can come from atmospheric carbon dioxide.

A dramatic change in atmospheric density remains one of the most intriguing possibilities about early Mars. Increasing evidence for liquid water on the surface of ancient Mars for extended periods continues to suggest that the atmosphere used to be much thicker.

The Technical Low-Down

The observations for this study were made using 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, which raises a number of questions about Mars’s early atmosphere and interactions of that atmosphere with the surface.

HiRise, Mars, mars climate, Mars Phoenix Lander, Mars Reconnaissance Orbiter

“I Can See the Lander from Here…”

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Spotting Evidence of Human Exploration of Mars

As the Mars Phoenix lander started to get a glimpse of the Sun towards the end of the northern hemisphere winter, the Mars Reconnaissance Orbiters HiRISE camera was used to imaging the Phoenix landing site despite the low light levels.
As the Mars Phoenix lander started to get a glimpse of the Sun towards the end of the northern hemisphere winter, the Mars Reconnaissance Orbiter's HiRISE camera was used to image the Phoenix landing site despite the low light levels. (Courtesy NASA/JPL/University of Arizona)

Back in late (Earth) summer, the Mars Reconnaissance Orbiter HIRISE Camera  (MOR-HIRISE) took an image of an area near the north pole of Mars.  It shows that the region looks like a frigid wasteland — which it is during Mars winter.  But, smack in the middle of the image is something kinda neat — the Mars Phoenix Lander — standing out against the background terrain.

Phoenix was sent to measure conditions for a short time near the pole. It performed quite well before going to sleep during the onset of northern hemisphere winter. For now it is dormant and quite possibly dead.  Scientists are going to try and communicate with it as spring approaches. In the meantime, though, the MRO continues to study the surface in the polar regions to help us understand what sorts of changes it goes through during the yearly freeze and thaw cycle.

In this portion of the larger image returned by the HIRISE camera, the large expanse of white area doesn’t actually doesn’t indicate the amount of frost surrounding the lander.  Since this image was taken in a low-light situation, its bright and dark values have been stretched to bring out the contrast and allows us to see details in the surface near the lander. Many factors affect how the surface looks in an image. Scientists need to take into account the size of carbon dioxide ice grains mixed in with the surface soil, the amount of dust mixed in with the ice, the amount of sunlight hitting the surface, and different lighting angles and slopes. In addition, the winds blow here constantly, and their directions change all the time.  Depending on how strong the winds are,they can move loose frost and dust around, changing the way the surface looks. Studying these changes will help planetary scientists understand the nature of the seasonal frost and winter weather patterns in this area of Mars.

I think it’s pretty amazing we can spot evidence of our robotic exploration on Mars. So far as the evidence from the various mappers and orbiters have shown us, humans are the ONLY ones to have explored Mars in its history — and that makes this pretty darned unique!