NASA Images Showcase the Eerie Beauty of Winter on Mars

CNN reports:Mars may seem like a dry, desolate place, but the red planet transforms into an otherworldly wonderland in winter, according to a new video shared by NASA.... "Enough snow falls that you could snowshoe across it," said Sylvain Piqueux, a Mars scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, in a statement from a NASA release. "If you were looking for skiing, though, you'd have to go into a crater or cliffside, where snow could build up on a sloped surface." So far, no orbiters or rovers have been able to see snow fall on the red planet because the weather phenomenon only occurs at the poles beneath cloud cover at night. The cameras on the orbiters can't peer through the clouds, and no robotic explorers have been developed that could survive the freezing temperatures at the poles. [ -190 degrees Fahrenheit, or -123 degrees Celsius) ] However, the Mars Climate Sounder instrument on the Mars Reconnaissance Orbiter can detect light that's invisible to the human eye. It has made detections of carbon dioxide snow falling at the Martian poles. The Phoenix lander, which arrived on Mars in 2008, also used one of its laser instruments to detect water-ice snow from its spot about 1,000 miles (1,609 kilometers) away from the Martian north pole.... "Because carbon dioxide ice has a symmetry of four, we know dry-ice snowflakes would be cube-shaped," Piqueux said. "Thanks to the Mars Climate Sounder, we can tell these snowflakes would be smaller than the width of a human hair." Ice and carbon dioxide-based frosts also form on Mars, and they can occur farther away from the poles. The Odyssey orbiter (which entered Mars' orbit in 2001) has watched frost forming and turning to a gas in the sunlight, while the Viking landers spotted icy frost on Mars when they arrived in the 1970s. At the end of winter, the season's buildup of ice can thaw and turn into gas, creating unique shapes that have reminded NASA scientists of Swiss cheese, Dalmatian spots, fried eggs, spiders and other unusual formations. That's just the beginning, according to a press release from NASA's Jet Propulsion Lab:This "thawing" also causes geysers to erupt: Translucent ice allows sunlight to heat up gas underneath it, and that gas eventually bursts out, sending fans of dust onto the surface. Scientists have actually begun to study these fans as a way to learn more about which way Martian winds are blowing. And they also note that the camera aboard NASA's Mars Reconnaissance Orbiter also captured some surprisingly colorful images of sand dunes covered by frost

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