NASA explores a winter wonderland on Mars

Dice-shaped snow, icy landscapes, and frost are all a part of the Purple Planet’s coldest season.

When winter involves Mars, the floor is reworked into a really otherworldly vacation scene. Snow, ice, and frost accompany the season’s sub-zero temperatures. A few of the coldest of those happen on the planet’s poles, the place it will get as little as minus 190 levels Fahrenheit (minus 123 levels Celsius).

Chilly as it’s, do not anticipate snow drifts worthy of the Rocky Mountains. No area of Mars will get various toes of snow, most of which falls over extraordinarily flat areas. And the Purple Planet’s elliptical orbit means it takes many extra months for winter to return round: a single Mars yr is round two Earth years.

Nonetheless, the planet affords distinctive winter phenomena that scientists have been in a position to research, due to NASA’s robotic Mars explorers. Listed below are just a few of the issues they’ve found:

Two sorts of snow

Martian snow is available in two varieties: water ice and carbon dioxide, or dry ice. As a result of Martian air is so skinny and the temperatures so chilly, water-ice snow sublimates, or turns into a fuel, earlier than it even touches the bottom. Dry-ice snow really does attain the bottom.

“Sufficient falls that you could possibly snowshoe throughout it,” stated Sylvain Piqueux, a Mars scientist at NASA’s Jet Propulsion Laboratory in Southern California whose analysis contains a wide range of winter phenomena. “In case you had been on the lookout for snowboarding, although, you’d have to enter a crater or cliffside, the place snow might construct up on a sloped floor.”

How we all know it snows

Snow happens solely on the coldest extremes of Mars: on the poles, underneath cloud cowl, and at night time. Cameras on orbiting spacecraft cannot see by way of these clouds, and floor missions cannot survive within the excessive chilly. Consequently, no photographs of falling snow have ever been captured. However scientists realize it occurs, thanks to a couple particular science devices.

NASA’s Mars Reconnaissance Orbiter can peer by way of cloud cover utilizing its Mars Local weather Sounder instrument, which detects mild in wavelengths imperceptible to the human eye. That skill has allowed scientists to detect carbon dioxide snow falling to the bottom. And in 2008, NASA despatched the Phoenix lander inside 1,000 miles (about 1,600 kilometers) of Mars’ north pole, the place it used a laser instrument to detect water-ice snow falling to the floor.

Cubic snowflakes

Due to how water molecules bond collectively once they freeze, snowflakes on Earth have six sides. The identical precept applies to all crystals: The best way during which atoms prepare themselves determines a crystal’s form. Within the case of carbon dioxide, molecules in dry ice all the time bond in types of 4 when frozen.

“As a result of carbon dioxide ice has a symmetry of 4, we all know dry-ice snowflakes could be cube-shaped,” Piqueux stated. “Due to the Mars Local weather Sounder, we will inform these snowflakes could be smaller than the width of a human hair.”

Jack Frost nipping at your rover

Water and carbon dioxide can every kind frost on Mars, and each varieties of frost seem much more extensively throughout the planet than snow does. The Viking landers noticed water frost once they studied Mars within the Seventies, whereas NASA’s Odyssey orbiter has noticed frost forming and sublimating away within the morning sun.

Winter’s wondrous finish

Maybe probably the most fabulous discovery comes on the finish of winter, when all of the ice that constructed up begins to “thaw” and sublimate into the ambiance. Because it does so, this ice takes on weird and delightful shapes which have reminded scientists of spiders, Dalmatian spots, fried eggs, and Swiss cheese.

This “thawing” additionally causes geysers to erupt: Translucent ice permits daylight to warmth up fuel beneath it, and that fuel finally bursts out, sending followers of dust onto the floor. Scientists have really begun to review these followers as a method to be taught extra about which approach Martian winds are blowing.