Вид на гору Олімп, де видно широку ділянку тонкого льоду. Зображення: ESA/DLR/FU Berlin
Previously, it was believed that there was no water ice in this region (equivalent to the tropics on Earth), so the latest discovery should radically change the modeling of future Mars exploration missions.
The European Space Agency’s (ESA) spacecraft, first the ExoMars Trace Gas Orbiter and then the Mars Express, have spotted water ice at the equator of Mars, namely in Farsidia, the largest volcanic region of the Red Planet.
Tharsis contains 12 volcanoes and boasts the highest peak in the entire solar system, Mount Olympus, at —29.9 km (2.5 times higher than Mount Everest).
«We thought that frost could not form around the equator of Mars because the combination of sunlight and a thin atmosphere keeps the temperature relatively high both on the surface and on top of the mountain — unlike what we see on Earth», — said Adomas Valantinas, a doctoral student at the University of Bern, Switzerland.
Frost spots appear only for a few hours before sunrise, and when the light hits the equator, they evaporate. Despite the fact that this frost is quite thin (equivalent to the thickness of a human hair — about one hundredth of a millimeter), it covers a huge area of each of the volcanoes. According to the researchers, this volume is enough to fill about 60 Olympic swimming pools (111 million liters of water) with water.
Each of the volcanoes where the frozen water was spotted contains deep depressions on their summits — so-called calderas, which form as magma chambers during eruptions. The team believes that the strange way the air circulates over the Farsida region creates a certain microclimate in these calderas that differs from the climate in which other volcanoes are located, and it is this microclimate that contributes to the formation of frost.
«Winds move up mountain slopes, bringing relatively humid air from the surface to higher altitudes, where it condenses and settles as frost», explains Nicholas Thomas, principal investigator of the ExoMars Trace Gas Orbiter mission.
Thomas added that the frost the team noticed on the tops of Mars’ volcanoes seems to be deposited in shaded areas of the calderas, especially in regions with lower temperatures.
Adomas explained that there are several reasons why this frost on the equator of Mars has not been detected until now:
«First, we needed an orbit that would allow us to observe the location in the early morning. While two ESA orbiters – Mars Express and TGO – have such orbits and can conduct observations at any time of the day, many other agencies are instead synchronized with the Sun and can only conduct observations in the afternoon. Second, frost deposition is associated with colder Martian seasons, making the window for detecting it even narrower».
The team’s study was published on Monday (June 10) in the journal Nature Geoscience (via Space.com).