Category Archives: Mars

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!

Mars, Mars Express, water

Mars Express and the Story of Water on Mars

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Looking for Evidence of Mars Water

Mars 3d image
A 3D image of Aurorae Chaos and Ganges Chasma from Mars Express. Courtesy ESA.

I haven’t written about Mars lately, and since I’m still gathering material for my annual “gift” column, let’s look at the Red Planet. I got a press release from the Mars Express mission (run by the European Space Agency), talking about a region that connects the great Valles Marineris to nearby lowlands. If you ever get a chance to go to Mars (and that could be a distinct possibility for some in the next generation of explorers, Valles Marineris should be a “must see” stopping point. It’s a huge collection of canyons carved out by various geological processes on the Red Planet. Flooding certainly seems to have played a role there, so scientists have focused on the landforms in the regions in and around the Valles Marineris to see how they might have been created. I would imagine that future explorers will head there as soon as they can to get a better and more in-depth understanding of this fascinating region.

A Vision of Formerly Wet Chaos

Mars Express sent back an image of a region called Aurora Chaos, looks as if it has been wet (not to mention inundated) in the past. It what is called “chaotic terrain”, which is jumbled and blocky and was probably formed as the surface collapsed when subsurface ice melted and the water flowed away. Aurora, at its deepest point, is 4.8 kilometers (about 3 miles) lower than the surrounding surface area. That’s much deeper than the Grand Canyon here on Earth.

Aurora Chaos connects to a smoother, flatter area called Ganges Chasma, which also looks like it has been shaped by flowing water. It ends at a plateau region that has carved rocky regions that were likely formed by water or ice deposits that were at different levels during various parts of Mars’s geologic past. The whole area has faults cutting across it, which mean that some sort of activity cracked and broke the “rock basement” that formed these regions. Faults in rock can form when the surface drops, from earthquake activity, or from underground pressure related to volcanism (to name a few reasons).

Whatever activities shaped this region, they occurred early on in Martian history perhaps only in its first couple of billion years.

When the first Martians from Earth make their homes and do their science on the Red Planet, they’ll be able to dig into the surface and do “first person” surveys. What they find will supply rich details for the story of early Mars that spacecraft probes such as the Mars Express mission are telling us from orbit.