Dust devils caught in action in the Martian arctic

See:


And the same image magnified a bit:

You can read the press release here.

September 11, 2008 --- NASA's Phoenix Mars Lander has photographed several dust devils dancing across the arctic plain this week and sensed a dip in air pressure as one passed near the lander.

These dust-lofting whirlwinds had been expected in the area, but none had been detected in earlier Phoenix images.

The Surface Stereo Imager camera on Phoenix took 29 images of the western and southwestern horizon on Sept. 8, during mid-day hours of the lander's 104th Martian day. The next day, after the images had been transmitted to Earth, the Phoenix science team noticed a dust devil right away.

"It was a surprise to have a dust devil so visible that it stood with just the normal processing we do," said Mark Lemmon of Texas A&M University, College Station, lead scientist for the stereo camera. "Once we saw a couple that way, we did some additional processing and found there are dust devils in 12 of the images."

At least six different dust devils appear in the images, some of them in more than one image. They range in diameter from about 2 meters (7 feet) to about 5 meters (16 feet).

"It will be very interesting to watch over the next days and weeks to see if there are lots of dust devils or if this was an isolated event," Lemmon said.

The Phoenix team is not worried about any damage to the spacecraft from these swirling winds. "With the thin atmosphere on Mars, the wind loads we might experience from dust devil winds are well within the design of the vehicle," said Ed Sedivy, Phoenix program manager at Lockheed Martin Space Systems Company, Denver, which made the spacecraft. "The lander is very rigid with the exception of the solar arrays, which once deployed, latched into position and became a tension structure."

That's also the reason why we've never tried sending a flying vehicle to Mars, because the atmosphere is so thin (along with much less solar power) that it's not really worth trying. Venus is the opposite situation however: the atmosphere 50 km above the surface has the same atmospheric pressure as sea level here, and the planet rotates so slowly that a flyer can stay in sunlight 24 hours a (Terran) day.