Springtime Dynamics on Mars: Geysers and Avalanches Emerge

The arrival of spring on Mars is marked by intense geological activity, a phenomenon distinct from the seasonal changes experienced on Earth. Due to its axial tilt of approximately 25 degrees, Mars experiences four seasons, but each lasting nearly twice as long as those on our planet, given that a Martian year spans about 687 Earth days.

As the northern hemisphere transitions into spring, which officially commenced on November 12, 2024, the planet's surface undergoes dramatic transformations. Selina Diniega, a researcher at NASA's Jet Propulsion Laboratory, describes this seasonal shift as a period characterized by explosive geological phenomena.

With the thin Martian atmosphere, the frozen water and carbon dioxide present on the surface transition directly from solid to gas as temperatures rise. This process results in a highly active and often violent springtime, unlike the gentle awakenings of spring on Earth.

NASA's Mars Reconnaissance Orbiter (MRO), operational since August 2005, has been pivotal in observing these changes from above. The orbiter has captured striking images that illustrate the explosive nature of Martian spring.

One notable image reveals an avalanche on Mars, showcasing a 20-meter segment of frozen carbon dioxide breaking off from a cliff. Rising temperatures during this season lead to the cracking of ice, making such avalanches a common occurrence. Diniega notes that the MRO has been crucial in documenting these dramatic events over its nearly two-decade mission.

Another fascinating phenomenon observed is the explosive geysers on the Martian surface, which emerge as dark, fan-shaped formations. When sunlight penetrates the carbon dioxide ice, it heats the ground beneath, causing the ice to sublimate and build pressure that eventually results in eruptions. These geysers are expected to be most visible in December 2025, coinciding with spring in the southern hemisphere, where they are typically larger and more prominent.

As spring progresses, the melting of frozen carbon dioxide reveals unique landforms known as "araneidoform terrain," or spider-like structures, which can be over a kilometer wide and are characterized by numerous appendages. Although the exact processes that create these formations are not fully understood, researchers at JPL are actively trying to replicate Martian conditions to gain insights into their development.

The northern polar ice cap of Mars, approximately the size of Texas at 1,000 kilometers in diameter, also experiences notable changes during spring. Winds contribute to the unique spiral patterns observed in the ice cap, a result of the Coriolis effect, which bends wind paths due to the planet's rotation. These winds have carved deep canyons over time, with features like the Chasma Boreale, which rivals the Grand Canyon in both length and depth.

Moreover, the vigorous winds of Martian spring are instrumental in shifting sand dunes across the landscape, similar to the processes observed in Earth's deserts. The images captured by the MRO depict sand dunes surrounded by frost, remaining static while frozen, but becoming mobile as temperatures rise and the frost melts.

In summary, the onset of spring on Mars is a period of significant geological activity, characterized by explosive geysers, avalanches, and unique landforms. Researchers continue to study these phenomena to deepen our understanding of the Martian environment.