Instead of a winter wonderland, the Red Planet’s northern hemisphere undergoes an active — even explosive — spring thaw.
While New Year’s Eve is right around the corner here on Earth, Mars scientists are ahead of the game: The red planet completed one trip around the Sun on November 12, 2024, prompting a few researchers to raise a toast. .
But the Martian year, which is 687 Earth days, ends very differently in the planet’s northern hemisphere than it does in Earth’s northern hemisphere: as winter begins here, spring begins there. has been That means temperatures are rising and ice is thinning, causing avalanches to hit mountains, carbon dioxide gas from the ground, and powerful winds to reshape the Arctic. have been
“On Earth there’s a lot of movement as the water ice slowly melts in the spring. But on Mars, everything happens with a bang,” said Serena Danega, at NASA’s Jet Propulsion Laboratory in Southern California. Studies the surfaces of the planets.
The thin atmosphere of Mars does not allow liquids to accumulate on the surface like on Earth. Instead of melting, the ice turns directly into a gas. The sudden transition to spring means much more violent changes as both water ice and carbon dioxide ice — dry ice, which is much more abundant than frozen water on Mars — weakens and breaks up.
“You get a lot of cracks and explosions instead of melting,” Danega said. “I imagine it gets really noisy.”
Using cameras and other sensors aboard NASA’s Mars Reconnaissance Orbiter (MRO), launched in 2005, scientists study all of this activity to improve their understanding of the forces shaping Mars’ dynamic surface. Here’s some of what they track.
In 2015, MRO’s High Resolution Imaging Science Experiment (HiRISE) camera captured a 66-foot-wide (20-meter-wide) Carbon Dioxide Frostbite Observing such possibilities in freefall is a reminder of how different Mars is from Earth, Danega said, especially in the spring, when these surface changes are most noticeable.
“We’re lucky to have a spacecraft like MRO to observe Mars for as long as it takes,” Deniga said. “Nearly 20 years of observation have allowed us to capture dramatic moments like these avalanches.”
Danega has relied on HiRISE to study another quirk of the Martian spring: gas geysers that erupt from the surface, spewing black fans of sand and dust. These explosive jets are formed by the energetic sublimation of carbon dioxide ice. As sunlight shines through the ice, its lower layers turn into gas, building up pressure until it bursts into the air, creating dark fans of material.
But to see the best examples of the latest fans, researchers will have to wait until December 2025, when spring begins in the Southern Hemisphere. There, the fans are larger and more clearly defined.
Another difference between ice-related action in the two hemispheres: Once all the ice around some northern geysers melts in the summer, what’s left behind is a trail of dirt that’s been spewed from space by giant spider legs. look like The researchers Recently recreated the process At JPL Lab.
One of the most interesting subjects this spring is for Isaac Smith of Toronto’s York University A snow cap the size of Texas At the North Pole of Mars. The ice dome has swirling troughs that reveal traces of the red surface below. The effect is similar to the swirling of milk in a cafe latte.
“These things are huge,” Smith said, noting that some are as tall as California. “You can find similar troughs in Antarctica but nothing on this scale.”
Strong, warm air has carved the spiral shapes over the years, and the troughs serve as channels for springtime winds that become stronger as the Arctic ice melts. Just like the Santa Ana winds in Southern California or the Chinook winds in the Rocky Mountains, these gusts pick up speed and temperature as they move down troughs—known as the adiabatic process.
The winds that carve the Arctic troughs also take on new forms. Mars sand dunesThis leads to accumulation of sand on one side while removal of sand on the other side. Over time, this process causes the dunes to migrate, just as it does with dunes on land.
This past September, Smith had a Paper Explaining how carbon dioxide freezes over polar sand dunes during winter, freezing them in place. When all the frost melts in the spring, the dunes begin to migrate again.
Every northern spring is a little different, with variations in the snow making faster or slower, which controls the speed of all these phenomena on the surface. And these strange phenomena are only part of the seasonal changes on Mars: the southern hemisphere has its own unique activity.
The University of Arizona, in Tucson, operates HiRISE, which was built by Ball Aerospace and Technologies Corp. in Boulder, Colorado. NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Exploration Orbiter project for NASA’s Science Mission Directorate, Washington.
For more information, visit:
https://science.nasa.gov/mission/mars-reconnaissance-orbiter
Andrew Good
Jet Propulsion Laboratory, Pasadena, California
818-393-2433
andrew.c.good@jpl.nasa.gov
Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
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