01-01-2025

New year on Mars: Avalanches, icy explosions, and the arrival of spring

Earth.com staff writer

While Earth celebrates the advent of a northern hemisphere New Year amidst winter chills, Mars embraces the start of spring.

On November 12, 2024, the Red Planet completed another journey around the Sun, marking this the beginning of a Martian year – a cycle that lasts 687 Earth days.

Springtime on Mars triggers unique and explosive transformations, including avalanches, as temperatures rise and ice begins to thaw.

“Springtime on Earth has lots of trickling as water ice gradually melts. But on Mars, everything happens with a bang,” said Serina Diniega, a planetary surface researcher at NASA’s Jet Propulsion Laboratory (JPL).

Unlike on Earth, Mars’s thin atmosphere doesn’t support liquid water. Ice sublimates directly into gas, creating dramatic phenomena that NASA scientists are closely monitoring using the Mars Reconnaissance Orbiter (MRO).

The arrival of spring on Mars

Mars’s cliffs roar to life during spring as frost avalanches cascade down their slopes.

In 2015, the High-Resolution Imaging Science Experiment (HiRISE) camera aboard the MRO captured a remarkable moment – a 66-foot-wide chunk of frozen carbon dioxide in mid-fall.

Martian spring involves lots of cracking ice, which led to this 66-foot-wide (20-meter-wide) chunk of carbon dioxide frost captured in freefall by the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter in 2015. Credit: NASA/JPL-Caltech/University of Arizona

“We’re lucky we’ve had a spacecraft like MRO observing Mars for as long as it has,” Diniega shared. “Watching for almost 20 years has let us catch dramatic moments like these avalanches.”

These avalanches highlight the dramatic environmental shifts that occur on Mars, offering scientists a chance to understand its dynamic surface better.

Explosive gas geysers

As sunlight penetrates frozen carbon dioxide, the bottom layers sublimate into gas, causing pressure to build.

Eventually, the gas erupts through the surface, creating geysers that spray dark fans of sand and dust. These explosive jets are unique to Martian spring and offer a stark contrast to Earth’s gentle seasonal transitions.

“You get lots of cracks and explosions instead of melting,” Diniega said. “I imagine it gets really noisy.”

While these fans are visible across the planet, the most dramatic examples appear during southern spring, which starts in December 2025.

Spider-like scour marks on Mars

Mars’s southern hemisphere presents a fascinating phenomenon: spider-like patterns that form on its surface due to erupting geysers.

These patterns, known as “araneiforms,” are created when sunlight penetrates layers of translucent frozen carbon dioxide.

As the ice sublimates directly into gas during spring and summer, the trapped gas builds pressure until it bursts through the surface.

Sometimes, after carbon dioxide geysers have erupted from ice-covered areas on Mars, they leave scour marks on the surface. When the ice is all gone by summer, these long scour marks look like the legs of giant spiders. Credit: NASA/JPL-Caltech/University of Arizona

This eruption sends dust and debris outward, carving branching, spider-like marks into the ground. Once all the frozen carbon dioxide has sublimated, these marks remain visible, resembling the legs of giant spiders.

To understand this process, NASA scientists have recreated it in controlled conditions at the Jet Propulsion Laboratory.

Power of Mars’s spring winds

The Martian north pole, home to a Texas-sized ice cap, experiences the relentless power of springtime winds. These gusts carve spiral troughs into the ice cap, revealing traces of the red soil beneath.

“These things are enormous,” said Isaac Smith from Toronto’s York University. “You can find similar troughs in Antarctica but nothing at this scale.”

The winds accelerate as they move down the troughs, reshaping the icy surface through what scientists call an adiabatic process.

This process involves changes in air temperature and pressure, without the addition or removal of energy. Adiabatic processes on Earth give rise to the Santa Ana and Chinook winds.

Wandering dunes: Sand on the move

The powerful winds also affect the Martian sand dunes.

During winter, frozen carbon dioxide fixes the dunes in place. But when spring arrives, the frozen gas sublimates, allowing the dunes to resume their slow migration.

Surrounded by frost, these Martian dunes in Mars’ northern hemisphere were captured from above by NASA’s Mars Reconnaissance Orbiter using its HiRISE camera. Credit: NASA/JPL-Caltech/University of Arizona

This ongoing process, observed by researchers, highlights how seasonal changes impact Martian landscapes.

A different world of ice and fire

Every northern spring on Mars is slightly different. Variations in temperature and sublimation rates influence the speed and intensity of these natural phenomena.

The dynamic interactions between frozen carbon dioxide, winds, and sand are crucial for understanding Mars’s past and future.

NASA’s Mars Reconnaissance Orbiter, equipped with the HiRISE camera and other sensors, has been pivotal in uncovering these extraordinary events.

Managed by NASA’s JPL, the MRO has provided nearly two decades of continuous observations, allowing researchers to capture Mars’s explosive beauty in unprecedented detail.

With each Martian year that passes, scientists gain deeper insights into the planet’s extreme seasonal transformations, which differ vastly from Earth’s.

Whether it’s avalanches, geysers, “spider legs” or wandering dunes, spring on Mars is a spectacle of cosmic proportions.

Video Credit: NASA/JPL-Caltech

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