Mars is Weird: NASA Orbiter Shows “Dry Ice” Snow on Red Planet
While Curiosity has been getting a lot of well-deserved attention lately, it’s worth remembering that everyone’s favorite rover isn’t the only one doing cool stuff with Mars. When it’s not getting some glamour shots of its ground-based cousin, the Mars Reconaissance Orbiter (MRO) is still finding out all sorts of neat things about our nearest sibling in the solar system, like confirming the suspicion that Mars has instances in which it snows dry ice — carbon dioxide that has frozen at temperatures below -193 degrees Fahrenheit.
The super-cold snowfall takes place at the Martian poles, where solid dry ice has been known to exist for some time. It has never been observed as falling snow, though, so its origins, though suspected, remained uncertain. Not anymore, though. Analysis of clouds of CO2 imaged by the MRO in the Martian winter of 2006-2007 demonstrates that in addition to familiar, hydrogen dioxide snow, which was seen on the planet in 2008 by the Phoenix lander, the red planet gets snowstorms of frozen carbon dioxide.
“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,” points out JPL’s David Kass, one of the authors of the study released today. Combined with an angling of the MRO’s instrumentation that allows it to tell dry ice frozen on the ground from fresh snowfall, the conclusion that frozen, solid carbon dioxide is precipitating to the Martian surface is inescapable.
It is also, for the record, really badass, and seeing that stuff is absolutely another argument for getting some manned missions to Mars.