Ice on Mercury in permanently shaded craters at the poles

There might actually be ice on Mercury, the closest planet to the Sun in our solar system. Although it’s hard to believe that ice could be present on a planet that exceeds 400 °C in surface temperatures, a new study shows that ice could exist thanks to the same heat as the planet.

On Mercury, in fact, there are small areas in craters at the poles that basically never see sunlight. Ice can form in these areas, as scientists at the Georgia Institute of Technology explain.
The model developed by the researchers sees first of all the extreme heat of the planet releasing the so-called hydroxyl groups, minerals present in the surface soil of the planet. This process leads to the production of water and hydrogen molecules that rise up as they move around the planet.

Most water molecules are decomposed by sunlight or rise far above the surface of the planet itself. However, some of these molecules end up landing in the above areas near the poles, areas in permanent shade due to the crater formation.
Since there is no atmosphere on Mercury, there is not even a transmission of air that can conduct heat. This means that these water molecules that go to rest inside these shaded craters freeze permanently.

“It’s a bit like the Hotel California song. Water molecules can get into the shadows but they can never leave,” explains Thomas Orlando, the studio’s lead author.
This process would form up to 10 percent of the total ice on the planet and could form up to 1013 kilograms of ice in 3 million years.

On the other hand, already in 2011, NASA’s MESSENGER space probe had identified the presence of typical signs of ice around the poles, signs that indicated the presence of “dirty” ice hiding in the permanent shadow in the polar craters, craters naturally formed by the impact of asteroids and meteorites in the planet’s past.