Snow On Mars: NASA Spacecraft Spots "Dry Ice" Snowflakes
A NASA spacecraft orbiting Mars found snow falling on the red planet -- but it's not what you think. The snow is actually frozen carbon dioxide, and the red planet is the only body in the solar system known to host such a phenomenon.
The snow on mars fells from clouds on the planet's south pole during the 2006 and 2007 Martian winter, but scientists only discovered it while sifting through older observations by the Mars Reconnaissance Orbiter. The Martian south pole has a persistent dry ice cap, and the new discovery may explain how it forms and continues to build, researchers said.
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"These are the first definitive detections of carbon-dioxide snow clouds," Paul Hayne, a researcher at NASA's Jet Propulsion Laboratory, said, according to Space.com. 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 researchers studied data from the MRO's Climate Sounder instrument, which measures the brightness of nine wavelengths of light, which allows researchers to determine factors such as particle size and composition of characteristics of the Martian atmosphere.
The team investigated several clouds the Climate Sounder took measurement of, including one 300 miles wide. By looking at the cloud directly overhead and again from the side, researchers were able to determine that the snow falling was actually dry ice.
"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," David Kass, also from the Jet Propulsion Laboratory, told Space.com. "Another comes from observations when the instrument is pointed toward the horizon, instead of down at the surface."
Although it's clear that carbon dioxide snow is falling on the planet, researchers said they aren't sure how it built up into the thick cap seen on the south pole.
"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 said.
The finding will be published in an upcoming issue of the journal Geophysical Research.
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