NASA reveals the mysterious beauty of winter on Mars; see images

Mars may seem like a dry and inhospitable place, but the red planet transforms into an otherworldly paradise 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 the Ingenuity helicopter are exploring an ancient river delta that once fed Jezero Crater billions of years ago.

As the main feature of the planet, dust also determines the Martian climate. Dust often 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 123 degrees Celsius.

There are two types of snow on Mars. One is the kind we experience on Earth, made from frozen water. Thin Martian air and subzero temperatures mean that traditional snow sublimates, or transitions from a solid directly to a gas, before touching down on Mars.

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

“Enough drops that you can snowshoe across it,” Sylvain Piqueux, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. “If you were looking to ski, though, you would have to go into a crater or cliff, where snow could build up on a sloping surface.”

Until now, no orbiters or rovers have been able to see snow fall on the red planet because the weather phenomenon only occurs at the poles under cloud cover at night. Orbiters’ cameras cannot peer through clouds, and no robotic explorers that could survive the freezing temperatures at the poles have been developed.

However, the Mars Climate Sounder instrument on the Mars Reconnaissance Orbiter can detect light that is invisible to the human eye. He made detections of carbon dioxide snow falling at the Martian poles. The Phoenix spacecraft, which arrived at Mars in 2008, also used one of its laser instruments to detect frozen snow from its location about 1,000 miles (1,609 km) away from the Martian North Pole.

Thanks to photographers, we know that snowflakes on Earth are unique and have six sides. Under a microscope, Martian snowflakes would probably look a little different.

“Since carbon dioxide ice has a symmetry of four, we know that dry ice snowflakes would be cube-shaped,” Piqueux said. “Thanks to the Mars Climate Sounder, we can say that these snowflakes would be smaller than the width of a human hair.”

Ice and carbon dioxide-based frosts also form on Mars and can occur farther from the poles. The Odyssey orbiter (which entered Mars orbit in 2001) observed ice forming and turning to gas in sunlight, while Viking landers spotted ice on Mars when they arrived in the 1970s.

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

During the winter at Jezero Crater, recent highs were around -13°C, while lows were around minus -84°C.

Meanwhile, in Gale Crater in the southern hemisphere near the Martian equator, the Curiosity rover, which landed on Mars in 2012, experienced maximums of -15°C and minimums of -76°C.

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

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

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