According to experts, high temperatures help in the formation of hydroxyls, molecules essential for the formation of water.
Although it is already surprising that there is ice on Mercury, where daytime temperatures reach 400ºC, a new article published in Astrophysical Journal Letters argues that it is this heat that makes ice possible on the planet. Crazy, right?
Just as on Earth, most of the water on the planet was brought in by asteroids. Experts believe that the high temperatures, combined with the negative 200ºC cold (temperature in the planet’s polar craters), form a kind of “chemical laboratory”.
“This is not a strange idea, outside the [astronomy] field. The basic chemical mechanism has been observed dozens of times in studies since the late 1960s,” said Brant Jones, one of the researchers, in a statement. “But that was on well-defined surfaces. Applying that chemistry to complicated surfaces like those on a planet is groundbreaking research.”
How heat helps to form ice
As scientists explain, minerals in Mercury’s soil contain hydroxyls (OH), which are mainly formed by protons. The extreme heat helps to release these substances from the surface, which end up energized, and collide, producing water and hydrogen molecules that float around the planet.
Some of these molecules are broken by sunlight, others end up moving too far from the surface, however, some lucky ones fall close to the icy poles of Mercury, in places permanently protected from heat.
“The total amount we postulate that would become ice is 10 ^ 13 kg (10,000,000,000,000 kg) over 3 million years,” explained Jones. “The process can easily be responsible for up to 10% of Mercury’s total ice.”
Now, remember that hydroxyls are mainly made up of protons? Where do these protons come from?
They come from the Sun, of course! Protons derived from solar winds are more abundant on Mercury than on Earth, where our powerful magnetic field forms a barrier and prevents these particles from entering the atmosphere. Mercury’s magnetic field is equivalent to just 1% of that of Earth, which allows protons and other particles to easily reach the planet’s surface.
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According to the scientists, the protons sent by the Sun are implanted in Mercury’s soil all over the planet, allowing the formation of hydroxyls. “They are like great magnetic tornadoes. They cause immense proton migrations over most of Mercury’s surface over time,” said Thomas Orlando, who also participated in the research.
Still, scholars believe that most of the water on Mercury comes from falling asteroids. “A comet or asteroid actually doesn’t need to carry water because the collision alone with a planet or moon can also make water,” explained Orlando. “Both Mercury and the Moon are always being hit by small meteoroids, so it happens all the time.”