Category Archives: HiRise

dust devils, HiRise, Mars, Mars Reconnaissance Orbiter

It’s Windy on Mars!

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Dust Devils Just Keep on Dancing Across Mars

Okay, a few weeks ago we had a week’s worth of high winds where I live, typical for Colorado in the late winter.  We call ’em Chinook winds, and they tend to dry things out as they blow at speeds upwards of 70 to 90 mph (112-144 km/hour) and gusts up above 100 (160 km/hr).  That’s all part of a weather pattern that occurs here, and in other parts of the world as the seasons change.  Right now, as we saw in Texas a few days ago, the winds and the associated weather patterns whip up twisters, tornadoes, dust devils.

The winds blow on Mars, too, and the Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera has been very good at spying out Martian dust devils.  Unlike a tornado which we see here on Earth, a dust devil typically forms on a clear day when the ground gets heated by the Sun. That warms the air just above the ground, and that air rises quickly through a small pocket of cooler air above it. If the conditions are just right, the air can start to rotate, and as it does, it picks up dust.  This is a  frequent occurrence on Mars.

HiRise view of a dust devil on Mars, taken March 14, 2012. Courtesy NASA/HiRise Team.

On March 14th, HiRISE caught sight of a Martian dust devil roughly 12 miles high (20 kilometers) whirling through a region called Amazonis Planitia.   The dust devil about (70 yards, or just about 70 meters across). The image was taken during late northern spring, two weeks short of the northern summer solstice, a time when the ground in the northern mid-latitudes heats up in the sunlight.

One of the cool things about these dust devils is that they scour the ground of dust, leaving behind a thin, sinuous little path. When those little paths were discovered, their appearance and cause was unknown. It didn’t take long for scientists to connect them with the appearances of dust devils. It appears that these dust devils are one mechanism by which dust gets redistributed around the Martian surface.

Check out the full story and a very cool animation showing what the dust devil might look like from the side at the NASA Mars Reconnaissance Orbiter page. It’s full of wooty Mars goodness!  And, if you experience winds and dust devils where YOU live on Earth, then you have a good idea of what it’s like on Mars when one goes twisting by!

 

 

HiRise, Mars, Mars Reconnaissance Orbiter

Avalanche Season on Mars

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Whoosh!

Avalanche clouds on Mars

It’s springtime on Mars and with it comes avalanches near the north polar cap!

The Mars Reconnaissance Orbiter HiRiSE camera team released this spectacular image of an avalanche on Mars.  The dust-like particles are hanging a few tens of meters above the surface in a rugged region near the north pole of the Red Planet.

These are likely caused when a avalanche of carbon dioxide frost slide down the steep cliff wall you see here.  The cliff itself is about 700 meters (2,000 feet) high and is a melange of layered water ice and dust. It’s very similar to what we see on Earth  near our poles (and in fact, reminds me of some snow “dunes” we have near our house that have been piled up since early in the year).  The bright stuff on the top surface is ice and frost made of carbon dioxide ice.

The cool thing about this view is that it’s helping the Mars scientists understand the processes that affect the Martian surface throughout the seasons, but especially during the freeze-and-thaw cycle that the planet experiences during late winter into spring.  The HiRiSE teams have been spotting avalanches pretty regularly, which gives them a lot to study. They now know that these things come thundering down in the middle of spring — say during the Mars equivalent of April to early May.   All together, it seems this is a regular spring process at Mars’s north pole that may be expected every year.  Now, all they have to do is figure out the sequence of events that lead to these spectacular events.  Stay tuned!