NASA Explores Winter in Wonderland on Mars – No Other Scenes Cube-Ancient Snow

data-gt-translate-attributes”[{” attribute=””>NASA’s spacecraft on and orbiting the Red Planet reveal the similarities to and differences from how we experience winter on Earth. Mars scientist Sylvain Piqueux of

Still, the planet offers unique winter phenomena that scientists have been able to study, thanks to NASA’s robotic Mars explorers. Here are a few of the things they’ve discovered:

Two Kinds of Snow

Martian snow comes in two varieties: water ice and carbon dioxide, or dry ice. Because Martian air is so thin and the temperatures so cold, water-ice snow sublimates, or becomes a gas, before it even touches the ground. Dry-ice snow actually does reach the ground.

“Enough falls that you could snowshoe across it,” said Sylvain Piqueux, a Mars scientist at NASA’s Jet Propulsion Laboratory in Southern California whose research includes a variety of winter phenomena. “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.”

HiRISE captured these “megadunes,” also called barchans. Carbon dioxide frost and ice have formed over the dunes during the winter; as this starts to sublimate during spring, the darker-colored dune sand is revealed. Credit: NASA/JPL-Caltech/University of Arizona

How We Know It Snows

Snow occurs only at the coldest extremes of Mars: at the poles, under cloud cover, and at night. Cameras on orbiting spacecraft can’t see through those clouds, and surface missions can’t survive in the extreme cold. As a result, no images of falling snow have ever been captured. But scientists know it happens, thanks to a few special science instruments.

NASA’s Mars Reconnaissance Orbiter can peer through cloud cover using its Mars Climate Sounder instrument, which detects light in wavelengths imperceptible to the human eye. That ability has allowed scientists to detect carbon dioxide snow falling to the ground. And in 2008, NASA sent the Phoenix lander within 1,000 miles (about 1,600 kilometers) of Mars’ north pole, where it used a laser instrument to detect water-ice snow falling to the surface.

NASA scientists can measure the size and shape of the distribution of snow particles, layer by layer, in a storm. The Global Precipitation Measurement mission is an international satellite project that provides next-generation observations of rain and snow every three hours around the world. Credit: NASA Goddard Space Flight Center/Ryan Fitzgibbons

Snow room

Because of how the water molecules bond with the solidification, snow on Earth has six sides. The same principle applies to all crystals: the way in which the atoms arrange themselves determines the shape of the crystal. In the case of carbon dioxide, the molecules in dry ice are always frozen in four forms.

“Because carbon dioxide ice has four-fold symmetry, we know that dry snow would be shaped like cubic ice,” Piqueux said. “Thanks to the Mars Climate Sounder we can say these snows will be smaller than the width of a human hair.”

The HiRISE camera captured this image on the rim of the crater in mid-winter. To the south of the slope of the crater, which receives less light, a variegated, bright frost has formed, enhanced by the blue in this image. Credit: NASA/JPL-Caltech/University of Arizona

Jack Frost Nipping at Your Rover

Water and carbon dioxide can each form ice on Mars, and both types of ice appear much more widely across the planet than snow. Viking landers saw frost water when they studied Mars in the 1970s, while NASA’s Odyssey orbiter observed frost forming and sublimating in the early morning sun.

Yesterday, the scene really captured this, when the frozen water on the ground split the ground into polygons. Translucent carbon dioxide ice allows sunlight to shine through and heat gases to escape through vents, releasing vents of darker material to the surface (as shown in blue in this enhanced-color image). Credit: NASA/JPL-Caltech/University of Arizona

A wonderful end to winter

Perhaps the most legendary discovery comes at the end of winter, when all the ice that has built up begins to “leak” and sublimate into the atmosphere. When he does this, these ices take on strange and beautiful shapes that have reminded scientists of spiders, Dalmatian spots, fried eggs, and Swiss cheese.

This “melting” also causes geysers to erupt: the translucent ice allows sunlight to heat the gas underneath, and the gas eventually erupts, sending fans of dust to the surface. Scientists really began to study these fans to learn more about which way the winds of March blow.