NASA images showcase eerie beauty of winter on Mars

Frozen ground ice left polygonal patterns on the Martian surface. (NASA, JPL-Caltech, University of Arizona)

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ATLANTA – Mars may seem like a dry and desolate place, but the red planet transforms into an otherworldly wonderland in winter, according to a new video shared by NASA.

It’s late winter in the northern hemisphere of Mars, where the Perseverance rover and Ingenuity helicopter are exploring an ancient river delta that once fed into Lake Jezero billions of years ago.

As a major feature of the planet, dust also drives the Martian weather. Dust usually heralds the arrival of winter, but the planet is no stranger to snow, ice and frost. At the Martian poles, the temperature can drop to minus 190 degrees Fahrenheit.

There are two types of snow on Mars. One is the kind we experience on Earth, made of frozen water. The thin Martian air and sub-zero temperatures mean that traditional snow sublimates, or goes from a solid directly into a gas, before it hits the ground on Mars.

The other type of Martian snow is carbon dioxide-based, or dry ice, and can land on the surface. Several meters of snow tend to fall on Mars in its flat regions near the poles.

“Enough precipitation to snowshoe across,” Sylvain Piqueux, a Mars scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement from a NASA news release. “If you were looking for skiing, however, you would have to go to a crater or cliff, where snow could pile up on a steep surface.”

So far, no orbiters or rovers have been able to see snowfall on the red planet, because the weather phenomenon only occurs at the poles under cloud cover at night. Cameras in orbit cannot see through clouds, and no robotic explorers have been developed that can survive the freezing temperatures at the poles.

Cracked carbon dioxide frost, or dry ice, can be seen inside a crater during winter in the Martian southern hemisphere. (Photo: NASA/JPL-Caltech/University of Arizona)

However, the Mars Climate Sounder instrument on the Mars Reconnaissance Orbiter can detect light that is invisible to the human eye. He has made discoveries of carbon dioxide snow falling on 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 location about 1,000 miles from the Martian north pole.

Thanks to photographers, we know that snowflakes on Earth are unique and six-sided. Under a microscope, Martian snowflakes would likely look a little different.

“Because carbon dioxide ice has a symmetry of four, we know that dry snowflakes would be cubic in shape,” Piqueux said. “Thanks to the Mars Climate Sounder, we can tell that these snowflakes would be smaller than the width of a human hair.”

Frosts based on ice and carbon dioxide also form on Mars and can occur further away from the poles. The Odyssey orbiter (which entered Mars orbit in 2001) has seen frost form and turn into gas in sunlight, while the Viking landers observed icy frost on Mars when they arrived in the 1970s.

In late winter, the season’s ice accumulation can melt and turn into gas, creating unique shapes that have reminded NASA scientists of Swiss cheese, Dalmatian spots, fried eggs, spiders and other formations. unusual.

During the winter at Jezero Crater, recent high temperatures have been around 8 F, while lows have been around minus 120 F.

Meanwhile, in Gale Crater in the southern hemisphere near the Martian equator, the Curiosity rover, which landed on Mars in 2012, has experienced highs of 5F and lows of minus 105F.

Seasons on Mars tend to be longer, because the planet’s oval-shaped orbit around the sun means that a single Martian year is 687 days, or nearly two Earth years.

NASA scientists celebrated the Martian New Year on December 26, which coincided with the arrival of the vernal equinox in the Northern Hemisphere.

“Scientists count the years of Mars starting from the planet’s northern vernal equinox that occurred in 1955 — an arbitrary point to start, but it’s useful to have a system,” according to a post on the NASA Mars Facebook page. “Counting Mars years helps scientists keep track of long-term observations, such as weather data collected by NASA spacecraft over decades.”

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