In 1991, astronomers on Earth sent radar signals to Mercury, and the feedback they received revealed that there might be ice layers at the poles of Mercury. At that time, astronomers were extremely interested in exploration. However, this phenomenon was not confirmed until 20 years later-in 2012, NASA’s “Messenger” spacecraft arrived in the sky above Mercury, and the spacecraft found huge water ice deposits in the Arctic region from Mercury’s 85° north latitude to the extreme. Things. So far, Mercury has officially joined the “Water Planet Club”. In the past nearly ten years, scientists have gained in-depth understanding of the specific location, thickness, and state of Mercury’s ice layer, but a core problem has not been resolved-where does the ice on Mercury come from?
The latest research shows that the water molecules in the ice layer on Mercury are actually produced under a high temperature environment of up to 400°C on the surface of Mercury. This is a bit surprising. In our opinion, it seems that high temperature and water cannot exist at the same time. According to common sense, as long as the temperature is higher than 100°C, water molecules will evaporate without a trace. A large part of the reason why the desert has become a desert is because the temperature is too high and the water has evaporated. How is the water on Mercury produced at high temperatures?
It turns out that the composition of minerals on the surface of Mercury contains hydroxyl groups. Hydroxyl is a common polar group consisting of a hydrogen atom and an oxygen atom. The chemical formula is -OH, which is only one hydrogen atom behind a water molecule. The reaction between the hydroxyl groups can produce water molecules, but the required reaction conditions are high. However, Mercury meets these reaction conditions. Because Mercury has almost no atmosphere and magnetic field, it cannot block the flow of charged particles from the sun (mainly protons and protons). Electronic) attack. Therefore, protons from the sun can directly rush into the soil on the surface of Mercury and combine with hydroxyl groups, reducing the ability of hydroxyl groups to combine with minerals. In addition, the extremely high temperature on the surface of Mercury excites the hydroxyl groups, causing them to collide frequently with each other, and finally the reaction of the hydroxyl groups to produce water and hydrogen molecules occurs. Some of the water molecules produced are decomposed by sunlight to produce hydrogen and oxygen; some escaped into space and left Mercury; some floated to the poles of Mercury, deep below the crater where the sun never shines. The temperature there can be as low as -172°C, so this part of the molecules solidified into ice and fell underground, forming a thick layer of ice.
Although many planets also have hydroxyl groups, these planets cannot meet the high temperature conditions, so they can only obtain water by colliding with meteorites that carry large amounts of water or water components (hydrogen and oxygen). Therefore, unlike other water-bearing planets, Mercury’s water is created by itself under high temperature conditions. Moreover, Mercury’s high-temperature ice-making behavior has been continuing: It is estimated that in the next 3 million years, Mercury will accumulate 10 trillion tons of ice in this way, which is approximately equivalent to the total amount of ice that can be observed on Earth. 10% of the amount.
