Frozen ice on the ground left polygonal patterns on the Martian surface. (NASA, JPL-Caltech, University of Arizona)
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ATLANTA — Mars may seem like a dry, desolate place, but the red planet is transforming into another winter wonderland, according to a new video shared by NASA.
It is late winter in the Northern Hemisphere of Mars, where the pirate Perseverance and Ingenuity are exploring the ancient Delta River that once fed the Lake Crater billions of years ago.
As a major planet, dust also drives Mars’ weather. Dust usually heralds the coming of winter, but the planet is no stranger to snow, frost and frost. At the poles of Mars, the temperature can dip as low as 190 degrees Fahrenheit.
There are two types of snow on Mars. One type that we experience on earth is made of frozen water. Mars’ thin air and subzero temperatures mean that traditional snow sublimates, or transitions from solid directly to gas, before reaching the ground on Mars.
Another type of Martian snow is carbon dioxide-based, or dry ice, that can land on the surface. A few feet of snow usually fall on their plains around the poles.
“It falls enough that you could snow through it,” said Sylvain Piqueux, a Mars scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, in a statement released by NASA. “If you were looking for skil, though, you’d have to go into a crater or a cliff, where the snow could build up in the highest drift.”
So far no orbiters or snow pirates have been able to see the snow on the red planet because the weather phenomenon only occurs at the poles under cloud cover at night. Cameras in orbit can’t see through clouds, and they haven’t developed robotic explorers that can survive the cold temperatures at the poles.
However, the Mars Climate Sensor Orbiter Mars Reconnaissance Orbiter can detect light that is invisible to the human eye. He made detections of carbon dioxide falling from the snow at the Martian poles. The Phoenix lander, which landed on Mars in 2008, also used a laser instrument to detect water-ice snow from its spot about 1,000 miles from the Martian north pole.
Thanks to photographers, we know that snow on Earth is unique and has six trilines. Under a microscope, Martian snow would look a little different.
“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.”
Ice and carbon dioxide-based ice also form on Mars and can reach far from the poles. The Odyssey orbiter (which entered Mars orbit in 2001) observed solar ice forming and turning on the Sun, while the Viking landers spotted ice on Mars when they arrived in the 1970s.
At the end of winter, the building ice of the season can turn and turn into steam, creating unique shapes that NASA scientists have mentioned as Swiss cheese, Dalmatian spots, fried eggs, spiders and other unusual formations.
In the winter, the recent high temperatures in Jezero Crater have been about 8 F, while the lows have been around 120 F.
Meanwhile, at Gale Crater in the Southern Hemisphere near the Martian equator, the Curiosity rover, which landed on Mars in 2012, has experienced temperatures as high as 5 F and as low as 105 F.
The seasons on Mars tend to last longer because the planet’s oval-shaped orbit around the sun means one Martian year is 687 days, or roughly two Earth years.
NASA scientists celebrated the Martian New Year on December 26, which coincides with the vernal equinox in the Northern Hemisphere.
“Scientists calculate Mars years from the northern vernal equinox that occurred in 1955 — an arbitrary point to start with, but a useful system to have,” according to a post on the NASA Mars Facebook page. “Counting the years of Mars helps scientists keep track of long-term observations, such as space weather data collected over a decade by NASA.”
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