Researchers Have Found 150,000 Tons of Ice on Mars Hidden in Plain Sight: In Its Volcanoes

It’s a fragile layer of frost that covers several volcanic craters.

Martian volcanoes
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Pablo Martínez-Juarez

Martian climatology has given us a new surprise. We’ve known for some time that it’s possible to find snow at the poles of the neighboring planet. Snow on Mars is like that on Earth but with an essential difference in its composition: carbon dioxide. Now, researchers have found frozen water on the Red Planet, but in a surprising location.

Icy craters. The new ice patches researchers found on Mars are in craters like those on Mount Olympus, the largest volcano in the Solar System. What’s surprising, however, is that some of these ice patches are in the planet’s equatorial belt, far from its poles.

“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,” Brown University postdoctoral student Adomas Valantinas explained.

Snow or frost? It’s tempting to imagine these Martian volcanoes as similar to Mount Rainier: a lone, snow-covered volcanic peak. However, the study refers to something more similar to frost.

According to initial analyses, it’s a fragile layer of frost with a thickness equivalent to a hundredth of a millimeter, or 10 microns (µm). Nevertheless, the area covered is so vast that the volume would be comparable to 60 Olympic-sized swimming pools, or a mass of 150,000 tons of water.

The research team believes that all of this water freezes during the Martian night and then melts when temperatures rise in the morning.

H2O or CO2? When we talk about snow on Mars, we usually refer to what we sometimes call dry ice, or frozen carbon dioxide. The Martian atmosphere contains a large amount of CO2. At the poles, low temperatures can cause this CO2 to freeze on the surface, forming large areas of snow.

How do we know that experts detected water and not carbon dioxide? No one has been able to verify this in situ. However, the team used some models that suggest these craters aren’t cold enough to freeze carbon dioxide. (It would be surprising if water ice could exist there).

Mars Express and TGO. The researchers analyzed the data by combining information from several instruments, including the European Space Agency’s Trace Gas Orbiter (TGO). This spacecraft carriesthe  CaSSIS (Color and Stereo Surface Imaging System), which captured some of the sunrise images of the Martian volcanoes.

The team validated these observations with other instruments, including the Nadir and Occultation for Mars Discovery spectrometer on the identical spacecraft and the high-resolution camera on the Mars Express spacecraft.

They examined 30,000 images of the Martian surface and published the results in Nature Geoscience earlier this week.

A climatic “remnant.” The research team explains that this may be one of the few remnants of the water cycle on Mars, a planet that probably lost its oceans billions of years ago.

We still have much to learn about this ice’s past and present. As the researchers explained, applying new models could reveal some of Mars’ secrets, such as where the remaining water is and what its dynamics look like. It could also highlight some critical aspects of future human missions to the neighboring planet.

Image | ESA/DLR/FU Berlin, A. Valantinas, CC BY-SA 3.0 IGO

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