When re-analyzing images and data from the Messenger probe, quite significant ice reserves were revealed not only in large, but also in small craters at the poles of Mercury, according to an article published in the journal Geophysical Research Letters.
“We believed that ice was present on the surface of Mercury only in large craters. But we found traces that there are also small deposits of water. If we calculate their total area and volume, then it is obvious that the water reserves on Mercury are significantly higher,”says Ariel Deutsch from Brown University (USA).
The US Aerospace Agency NASA launched the Messenger probe in 2004. It became the first spacecraft sent to Mercury after the Mariner-10 probe, which flew in close proximity to the "messenger" planet on March 16, 1975. In April 2015, after the depletion of fuel reserves, the Messenger was smashed against the surface of Mercury.
In June 2011, scientists discovered that the magnetic center of Mercury is not located in the center of the planet, but is displaced to the north, which is why the planet carries its magnetic field to one side. In addition, the "Messenger" found traces of "stormy volcanic youth" on Mercury and proved the possibility of the existence of frozen water in deep craters at the poles.
This discovery, according to Deutsch, was a big surprise for planetary scientists, but the conditions at the permanently dark poles of Mercury turned out to be favorable enough for the ice there not to melt under the influence of the solar wind and the rays of the sun. Trying to understand how he got there, Deutsch and his colleagues mapped the ice deposits on Mercury using data from the Messenger instruments.
According to planetary scientists, they looked for ice in a very simple way - they tracked how the albedo (reflectivity) changed at the bottom of large and small craters. Ice reflects light much better than the rocks of the first planet of the solar system, so you can find not only open deposits of frozen water, but also its reserves hidden under a thin layer of dust and debris.
As it turned out, the volume of ice reserves on Mercury was greatly underestimated: their total area in only the three largest craters, according to Deutsch and his colleagues, is at least 3.4 thousand square kilometers. No less ice reserves, according to planetary scientists, lie under the ground on the plains surrounding these craters, and in four small craters about five kilometers in diameter in the far north and south of Mercury.
This discovery makes the story of the appearance of ice on the surface of Mercury even more mysterious than before. According to planetary scientists, both comets and asteroids and the solar wind can be its source, and it is not yet clear which two hypotheses are closer to the truth. It is possible that the launch of the Russian-European probe BepiColombo next October will help uncover this mystery.
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