Category Archives: Curiosity

astronomy, Curiosity, Mars

Dunes! Mars! Yikes! Go Curiosity!

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Curiosity Shows a Dune World

Dunes on Mars
The rippled surface of the first Martian sand dune ever studied up close. It’s called “High Dune” as seen by the Curiosity rover.  NASA/JPL-Caltech/MSSS

The Mars Curiosity rover has been hitting them out of the park lately with one great image after another. The rover has been investigating active sand dunes rippling across the landscapes near Mt. Sharp on the Red Planet. Check out this high-resolution strip image to get an idea of this fantastic landscape and the dunes that lay scattered across this region of Mars.

Check Out Those Dunes!

This dune field is traveling across the Mars landscape, pushed by the action of the wind. On Earth, we know that dunes need a speed of around 17 miles per hour in order to travel. Sand particles travel up the windward side of the dune (that is, the part of the dune that faces toward the direction of the wind). Their motion is called “saltation”. The particles jump around, moving up the dune, as the wind toys with them. Then, once they reach the top, they fall down the other side, and get deposited in smooth hills.   Over time, the dune’s sand particles all move this way. That’s a general look at how a dune inches forward over time.

I’ve watched this happen at Sand Dunes National Park in Colorado, and more recently, I watched a similar action near my house. There’s a huge pile of snow, and as the wind blows, snow flakes and snow “balls” (tiny ones), move UP the windward side of the pile, and then deposit themselves on the other side.

Take a good close-up look at this image; click on it to enlarge. You’ll see all kinds of details in these dunes. It’s really impressive, and gives you a chance to explore Mars and its dues as Curiosity sees them!

Curiosity, Mars

Reading the Rock Record on Mars

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Mars Rocks!

This view from the Mast Camera (Mastcam) on NASA’s Curiosity Mars rover shows a site where two different types of bedrock meet on lower Mount Sharp. The rover is in a valley just below “Marias Pass.” The color has been approximately white-balanced to resemble how the scene would appear under daytime lighting conditions on Earth. The paler part of the outcrop, in the foreground, is mudstone similar to what Curiosity examined at “Pahrump Hills.” The darker, finely bedded bedrock higher in the image and overlying the mudstone stratigraphically is sandstone that the rover team calls the “Stimson” unit. The scene covers an area about 10 feet (3 meters) wide in the foreground. Courtesy: NASA/JPL-Caltech/MSSS

While we’re waiting for more news from New Horizons, I wandered over to the Mars Curiosity web site to look at what our intrepid rover has been doing since scientists regained communications with it. They didn’t have much contact with it when Mars was on the “other side” of the Sun during much of June, so the images slowed to a halt for a short time.

Curiosity is now exploring a region where the rocks are telling us a story about the environmental conditions on Mars in the distant past. The image here shows an area where two different rock types meet. One type is made up of light-colored mudstone, which indicates that the region was once under water that wasn’t moving very fast (if at all). The other type is a sandstone that appears to have been laid down in multiple layers as water moved across the surface.

What does that tell us about the long-term history of the planet? For now, it means that water once clearly existed in the region where Curiosity is studying the rocks. The mudstone was laid down by standing water, perhaps in a lake or a pond or a deep-ocean region. Mudstone is made of fine particles of rock that wafted to the bottom of the body of water and was allowed to rest before the water went away and the mud hardened to rock.

The sandstone is larger grained than the mud and silt, and it was likely carried along by a slow-moving current in a lake or sea, or by a quiet river. It had time to settle into layers and harden, so it’s unlikely that there were many catastrophic floods at the time the sandstone was laid down. If there had been floods, we’d see larger rocks embedded in the sand.

Rocks can tell us many stories about the environment, if we know how to read what they have to say. That’s the job of geology — to help us make sense of how the rocks were made, deposited, and perhaps carried along by water and wind.