This image shows Olympus Mons, the tallest volcano not only on Mars, but in the entire solar system. … [+]
Planetary scientists have long thought that the equatorial regions of Mars were too sunny and its atmosphere too thin to host frost or ice, but new images suggest otherwise.
A new article published in Nature Geoscience revealed that the European Space Agency’s ExoMars and Mars Express missions have for the first time observed water frost near the equator of Mars, on its Tharsis volcanoes, the tallest volcanoes in the solar system.
The area is home to the colossal Olympus Mons – three times taller than Mount Everest – and the Tharsis Montes shield volcanoes.
This high-resolution image shows newly discovered frost on top of Olympus Mons, the tallest … [+]
An exciting discovery
“We thought it was impossible for frost to form around the equator of Mars because the mixture of sunlight and thin atmosphere keeps the surface and mountaintop temperatures relatively high,” said lead author Adomas Valantinas, who made the discovery as a Ph.D. student at the University of Bern, Switzerland, and is now a postdoctoral fellow at Brown University in Providence, Rhode Island.
“Its existence is exciting and suggests that there are exceptional processes at play that allow ice to form,” he said.
Scientists discover ice on volcanoes near Martian equator for the first time – part … [+]
A unique microclimate
Mars is not like Earth, where frosty peaks are common. Mars has a low atmospheric pressure, which means that the mountain tops are about the same temperature as the plains. Scientists think what’s happening is that moist air is blowing up the mountainsides and condensing as frost in the cooler calderas of the Tharsis volcanoes. The air circulates in such a way that it creates an unprecedented microclimate.
The amount of frost on Mars is equivalent to about 60 Olympic swimming pools. It was detected in very thin areas but covers a large area. It only exists for a few hours around sunrise before it evaporates in the sunlight.
This simulated perspective oblique view shows Olympus Mons, the tallest volcano not only on Mars but also … [+]
A belated discovery?
The frost was discovered by the ExoMars TGO and Mars Express, which have been conducting orbital science since 2018 and 2003, respectively. So why did it take so long to find this microclimate on Mars? “We need an orbit that will allow us to observe the site early in the morning,” Valantinas said. Of the seven orbiters around Mars, all but ExoMars TGO and Mars Express are in sync with the Sun, so Mars can only be studied in the afternoon.
But there is another reason. “Frost deposition is associated with cooler Martian periods, making the window for observing it even narrower,” Valantinas said. “We have to know where and when to look for the passing frost. We happened to be looking for it near the equator for some other research, but we didn’t expect to see it on the tops of Martian volcanoes.”
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