Mars Becomes the Only Known Planet to Snow Dry Ice

A blizzard here on Earth is characterized by the dense, rapidly falling solid form of water. Recent research of a blizzard on the red planet though has found water might not be the only thing that can come down in the form of snow.

Now identified as the only planet in the solar system to exhibit this characteristic, Discovery News reports a NASA study finding that Mars has been precipitating dry ice -- or carbon dioxide at -193 degrees Fahrenheit. Although the presence of dry ice has been known on Mars for some time, how it came to compose much of the planet's ice caps and frost was unknown until now.

Evidence collected from Mars Reconnaissance Orbiter has found what Discovery News calls a "dry ice blizzard."

"These are the first definitive detections of carbon-dioxide snow clouds," the report's lead author, Paul Hayne of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. "We firmly establish the clouds are composed of carbon dioxide -- flakes of Martian air -- and they are thick enough to result in snowfall accumulation at the surface."

The data composing the evidence for the study was collected in the Mars winter of 2006-2007.

"One line of evidence for snow is that the carbon-dioxide ice particles in the clouds are large enough to fall to the ground during the lifespan of the clouds," co-author David Kass of JPL said in a statement. "Another comes from observations when the instrument is pointed toward the horizon, instead of down at the surface. The infrared spectra signature of the clouds viewed from this angle is clearly carbon-dioxide ice particles and they extend to the surface. By observing this way, the Mars Climate Sounder is able to distinguish the particles in the atmosphere from the dry ice on the surface."

This does not discount more traditional, water-based snow and frost on the planet. The research states that water-ice snow was observed falling on Mars in 2008.

This research was published in the Journal of Geophysical Research.

In other Mars news, the car-size rover Curiosity that landed on the planet in early August finishes up its diagnostic checks of its instruments this week before embarking on a mission to examine whether the environment could have been hospitable to microbial life.

Here are some recent photos from the rover:

It still has to do a final check of its robotic arm and aim its camera to track one of Mars' moons, Phobos, passing in front of the sun before hitting the road Friday night.

Curiosity is headed toward a spot called Glenelg where three types of terrain meet. Its ultimate destination will be Mount Sharp.

The Associated Press contributed to this report.