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Last Updated: Friday, 22 April 2005, 17:29 GMT 18:29 UK
Mars dust devils caught in action
Dust devil on Mars, Nasa
The images give scientists their best look yet at the "dust devils"
One of the US space agency's robot rovers on the Red Planet has captured whirlwinds, or "dust devils", churning their way across the Martian plain.

Spirit recorded images of the dust devils on 15 and 18 April; and these have now been turned into an animation.

The movies give mission scientists their best look yet at these mysterious planetary phenomena as they swirl across the surface of the Red Planet.

The Spirit rover has been exploring Gusev Crater since January 2004.

It has been using its navigation camera to routinely check for dust devils and began seeing the whirlwinds last month in individual frames captured with the camera.

Kicking dust

Mission scientist Dr Mark Lemmon, a rover team member from Texas A&M University in College Station, said: "We're hoping to learn about how dust is kicked up into the atmosphere and how the wind is interacting with the surface.

"It's exciting that we now have a systematic way of capturing dust devils in movies rather than isolated still images."

Similar phenomena - also called dust devils - occur on Earth. The Martian whirlwinds also resemble the tornadoes and waterspouts seen on our own planet.

The ultimate cause of the Martian phenomena remains unknown, but may be related to rising air heated by sun-warmed rocks and soil.

Intriguingly, rover engineers have noticed unexplained increases in the power available to Spirit.

One possibility is that dust devils passing nearby or above the rover have been cleaning its solar panels.

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