Winter causes Mars’ largest volcano to freeze

As winter mornings dawn on Mars, the summits of the planet’s largest volcanoes are covered in frost — another indication of the presence of water on the Red Planet.

We already know that Mars has large deposits of ice in the form of polar ice caps and possibly buried beneath the surface near the equator, but scientists have yet to observe surface water anywhere else on the planet.

Now, Admas Valantinus Valantinas, of Brown University in Rhode Island, and his colleagues found frost, which appears to form only in the mornings during the Martian winter, near the summits of volcanoes in the Tharsis region, including Olympus Mons, one of the solar system’s largest volcanoes. “This is really exciting, because it not only shows how dynamic the Martian water system is, but also that water could be found in varying amounts basically everywhere on Mars,” Valantinas says.

He and his team used a color camera on the European Space Agency’s Trace Gas Orbiter, which studies the Martian atmosphere, to take morning photographs of the icy volcano’s summit and found widespread blue frost. They calculated the surface temperature and found that it was too hot for carbon dioxide to freeze, and that similar-looking frozen carbon dioxide was not the cause.

Ice could form from gases erupting from volcanoes, but if so, do Valantinas and his team expect to see it year-round? Instead, the fact that it only appears during the colder parts of the year makes it more likely that the frost is the result of water vapor in the atmosphere freezing.

Knowing where ice forms on the Martian surface, especially from atmospheric processes, is crucial for accurate weather forecasting, he said. Susan Conway A researcher at the University of Nantes in France, she says we know that polar ice flows into the atmosphere, but we don’t know where it goes. “This is a really cool observation, because now we actually know where it goes.”