“Nature’s Fury: Unraveling the Mysteries of Avalanches, Frosty Eruptions, and Shifting Sands”

• Spring on Mars triggers explosive transformations. With rising temperatures, the northern hemisphere of Mars witnesses intense occurrences such as frost avalanches, geysers of carbon dioxide gas, and winds that reshape polar ice caps and dunes.
• Unlike on Earth, ice on Mars sublimates directly into gas. This sublimation leads to explosive phenomena like “spiders” (the scour marks created after ice sublimation) and dark fans of debris emerging from the gas geysers.
• The Mars Reconnaissance Orbiter is vital for investigating these dynamic processes for nearly two decades. It provides unparalleled images and insights into the transformation of the red planet’s surface.

NASA/JPL released this original article on December 20, 2024. Edits by EarthSky.

Mars is entering another 687-day-long cycle

While we here on Earth are welcoming New Year’s Eve, scientists studying Mars have already moved forward: The red planet completed its orbit around the sun on November 12, 2024, which prompted several researchers to celebrate.

However, the Martian year, spanning 687 Earth days, concludes in a significantly different manner in the planet’s northern hemisphere compared to Earth’s northern hemisphere. While winter approaches here, spring is beginning on Mars. This transition means rising temperatures and melting ice, resulting in frost avalanches cascading down cliffs, carbon dioxide gas bursting from the ground, and strong winds altering the landscape of the north pole.

Serina Diniega, who investigates planetary surfaces at NASA’s Jet Propulsion Laboratory in Southern California, remarked:

Spring on Earth features a gradual melting of water ice, but on Mars, everything happens explosively.

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Spring literally erupts on the red planet

Mars’ thin atmosphere prevents liquids from pooling on the surface as they do on Earth. Instead of melting, ice sublimates, transitioning directly into gas. The abrupt changes during spring lead to many explosive events as both water ice and carbon dioxide ice – dry ice, which is much more abundant on Mars compared to frozen water – weaken and fracture.

Diniega stated:

What you witness are numerous cracks and explosions instead of melting. I can imagine it gets quite noisy.

Utilizing the cameras and sensors onboard NASA’s Mars Reconnaissance Orbiter (MRO), which was launched in 2005, researchers observe this activity to advance their comprehension of the forces molding the ever-changing Martian surface. Here’s some of what they monitor.

Frost avalanches observed in real time on Mars

In 2015, MRO’s High-Resolution Imaging Science Experiment (HiRISE) camera documented a 66-foot-wide (20-meter-wide) piece of carbon dioxide frost in freefall. Chance observations like this highlight the stark differences between Mars and Earth, according to Diniega, particularly during spring when these surface alterations are most pronounced.

Diniega noted:

We’re fortunate to have a spacecraft like MRO observing Mars for such an extended period. Monitoring for nearly 20 years has allowed us to capture spectacular moments like these avalanches.

Gas geysers propel ‘spiders’ on the Martian southern hemisphere

Diniega has depended on HiRISE to investigate yet another unique characteristic of Martian springtime: gas geysers that explode from the surface, ejecting dark fans of sand and dust. These explosive jets arise from the vigorous sublimation of carbon dioxide ice. When sunlight shines through the ice, the lower layers convert to gas, building up pressure until it bursts, creating those dark fans of material.

However, in order to observe the most remarkable examples of these fresh fans, researchers must wait until December 2025, when spring begins in the southern hemisphere. There, the fans are larger and more distinctly formed.

Another distinction between the actions related to ice in the two hemispheres: after all the ice surrounding certain northern geysers sublimates during summer, the resulting soil is left with scour marks that resemble huge spider legs when viewed from space. Researchers have recently replicated this process in a JPL laboratory.

Intense winds create massive markings on Mars’ ice cap

For Isaac Smith from York University in Toronto, one of the most intriguing topics during spring is the Texas-size ice cap located at Mars’ northern pole. Carved into the icy surface are swirling channels, showcasing glimpses of the crimson ground beneath. The visual effect resembles the swirling of milk in a café latte.

Smith mentioned that some of these channels stretch as long as California:

These formations are immense. While you can find analogous channels in Antarctica, nothing matches this scale.

Rapid, warm winds have shaped the spiral patterns over millennia, and the channels function as conduits for springtime gusts that strengthen as the ice at the north pole begins to melt. Much like the Santa Ana winds in Southern California or the Chinook winds in the Rocky Mountains, these gusts increase in velocity and warmth as they descend through the channels in a process known as adiabatic process.

Sand dunes shift across the Martian terrain

The winds that sculpt the troughs of the north pole also modify Mars’ sand dunes, leading to the accumulation of sand on one side while simultaneously eroding sand from the other side. As a result, the dunes gradually migrate, similar to what occurs on Earth.

In September, Smith co-authored a paper outlining how carbon dioxide frost accumulates atop polar sand dunes during winter, effectively freezing them in place. As the frost melts away in spring, the dunes resume their migration.

Each northern spring varies slightly, with deviations causing ice to sublimate either more rapidly or slowly, influencing the rhythm of all these surface phenomena. Moreover, these peculiar occurrences form just a part of Mars’ seasonal transformations, as the southern hemisphere boasts its distinct activities.

In conclusion: A fresh and dynamic year commenced on Mars on November 14, 2024. NASA and its collaborators are observing the season’s peculiar and distinctive characteristics.

Read more: Mars is hastening toward opposition in January 2025: Start observing now!