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Huge amount of water frost "unexpectedly" found on Mars' volcanoes

An international team of planetary scientists has recently discovered patches of water frost atop the Tharsis volcanoes on Mars. These volcanoes are not only the tallest on Mars but in the entire solar system. 

This is the first time frost has been observed near Mars’ equator, challenging existing views of the planet’s climate.

Remnants of an ancient climate cycle 

“We thought it was improbable for frost to form around Mars’ equator, as the mix of sunshine and thin atmosphere keeps temperatures during the day relatively high at both the surface and mountaintop — unlike what we see on Earth, where you might expect to see frosty peaks,” said lead author Adomas Valantinas, a postdoctoral fellow at Brown University who led the work as a PhD student at the University of Bern

“What we’re seeing may be a remnant of an ancient climate cycle on modern Mars, where you had precipitation and maybe even snowfall on these volcanoes in the past.”

The study revealed that this frost is present only for a few hours after sunrise before evaporating in the sunlight. It is incredibly thin, likely about one-hundredth of a millimeter thick, roughly the width of a human hair. 

Water frost on Tharsis volcanoes

Despite its thinness, the frost covers a significant area. Researchers estimate that at least 150,000 tons of water cycles between the surface and atmosphere daily during the cold seasons, equivalent to about 60 Olympic-size swimming pools.

Water frost found on Mars' volcano Olympus Mons. Credit: ESA/NASA
Water frost found on Mars’ volcano Olympus Mons. Credit: ESA/NASA

The Tharsis region, where the frost was found, contains numerous towering volcanoes, some of which are one to two times the height of Earth’s Mount Everest. Olympus Mons, for example, is as wide as France. 

The frost is located in the calderas of these volcanoes, large hollows at their summits formed during past eruptions. The team suggests that air circulation above these mountains creates a unique microclimate allowing the frost to form.

Significance of frost on Mars

Modeling the formation of these frosts could help scientists uncover more of Mars’ secrets, including the distribution and movement of water and the planet’s complex atmospheric dynamics.

This is crucial for future exploration and the search for potential signs of life.

Perspective view of water frost on Mars' Olympus Mons. Credit: ESA/NASA
Perspective view of water frost on Mars’ Olympus Mons. Credit: ESA/NASA

The frost was detected using high-resolution color images from the Colour and Stereo Surface Imaging System (CaSSIS) onboard the European Space Agency’s Trace Gas Orbiter. 

The findings were validated with observations from the High Resolution Stereo Camera on the ESA’s Mars Express orbiter and the Nadir and Occultation for Mars Discovery spectrometer on the Trace Gas Orbiter.

Tracing the signatures of frost on Mars

The researchers analyzed over 30,000 images to initially find and then confirm the frost. Valantinas filtered the images based on their location, time of day, and season to isolate spectral signatures indicative of water frost and identify where it formed on Mars’ surface.

“This notion of a second genesis, of life beyond Earth, has always fascinated me,” said Valantinas, who began analyzing the images in 2018.

As he transitions to his role at Brown, Valantinas plans to continue exploring Martian mysteries, pivoting towards astrobiology.

Working with Brown planetary scientist Jack Mustard, he aims to characterize ancient hydrothermal environments that could have supported microbial life

Samples from these environments might be returned to Earth by the NASA-led Mars Sample Return mission.

Signs of life on Mars

Signs of life on Mars have been a subject of intense scientific investigation. Researchers have been particularly interested in the presence of water, as it’s a crucial ingredient for life. 

Liquid water

Mars rovers like Curiosity and Perseverance have found evidence of ancient riverbeds, lake beds, and mineral deposits that typically form in water, suggesting that Mars once had liquid water on its surface. 

Organic molecules 

Additionally, organic molecules, which are the building blocks of life, have been detected in Martian soil samples. 


Methane detection has also piqued interest because on Earth, methane is predominantly produced by biological processes. However, methane can also be generated by geological processes, so its presence alone does not confirm life. 

The seasonal fluctuations of methane observed by the Curiosity rover suggest that the gas may be produced and destroyed through unknown processes. 

Future missions

Despite these promising signs, no definitive evidence of current or past life on Mars has been found yet. Future missions aim to bring back samples to Earth for detailed analysis, which may provide clearer answers.

The study is published in the journal Nature Geoscience.

Image Credit: ESA/DLR/FU Berlin


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