Dry Ice Snowfalls on Mars Confirmed

First Posted: Sep 12, 2012 08:19 AM EDT

The data revealed by NASA's Mars Reconnaissance Orbiter data clearly indicates the presence of carbon dioxide snowfalls on Mars. This is the only example of carbon dioxide snow falling anywhere in the solar system.

Dry ice is formed in temperature of minus 193 degrees Fahrenheit. Carbon dioxide snowfalls reminds scientists that the red planet that is considered as inhabitable may look similar to Earth, but in real is very different.

The report is being carried in the Journal of Geophysical Research.

"These are the first definitive detections of carbon-dioxide snow clouds," said the report's lead author, Paul Hayne of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "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 presence of carbon dioxide ice in Mars has been for decades. It was in the year 2008 that NASA's Phoenix Lander mission observed falling water ice snow on the northern Mars.

The authors analyzed the data produced by the Mars Climate sounder that records brightness in nine wavebands of visible and infrared light as a way to examine particles and gases in the Martian atmosphere. The researchers learnt the temperatures, particle sizes and their concentrations.

"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. "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."

Mars' south polar residual ice cap is the only place on the Red Planet where frozen carbon dioxide persists on the surface year-round. 

"The finding of snowfall could mean that the type of deposition -- snow or frost -- is somehow linked to the year-to-year preservation of the residual cap," Hayne, a post-doctoral fellow at the California Institute of Technology in Pasadena said.

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