China finds rocks never seen on the Moon

by time news

Despite the fact that it is the only world other than Earth that human beings have stepped on with their own feet, the Moon continues to keep secrets. At least according to the samples collected by the Chinese rover Chang’e 5, remains that returned to our planet in December 2020 and that continue to surprise us. So far, up to seven different types of rock have been identified among the almost two kilos of regolith formed 2,000 million years ago. Now Chinese researchers have just discovered that one of the rocks is an entirely new type of lunar basalt, created at a time when the Moon was still volcanically active. The results have just been published in ‘Nature Astronomy’.

It is the youngest regolith to have been returned from the Moon to date (to date, only the Apollo missions and three Soviet missions from the 1970s had returned lunar samples), giving experts a window into a different time period and piece together a tumultuous period in our neighbor’s history.

The seven rock types listed in the study are considered “exotic,” and are believed to have arrived at their current landing site from elsewhere. “In such a young geologic unit, a wide range of crustal components from diverse sources would be transported to the Chang’e-5 landing site by the latest ongoing surface processes on the Moon,” the researchers write in their published paper. . That is to say, that the remains collected by the rover did not form there, but were transported by some type of geological mechanism.

The researchers sieved about 3,000 particles less than 2 millimeters in size. There they were looking for evidence of impact craters and past volcanic activity, in the same way that igneous rocks on Earth are looked for. “Three of the fragments were notable for displaying unusual petrological and compositional features,” the researchers say. The high-titanium vitrophic shard has mineralogy we haven’t seen before on the Moon and likely represents a new type of lunar rock, they say.

According to the authors, these rock particles may be associated with areas on the Moon as far as 400 kilometers from where they were collected, hurled across the surface by a succession of asteroid impacts over millennia. The bottom line is that these strange bits come from parts of the Moon’s surface that we don’t yet know about, in geological terms. There might even have been hidden volcanic eruptions.

Less exotic material than expected

Finding previously unseen components was something to be expected; however, forecasts said that these ‘exotic’ materials would make up between 10 and 20 percent of the total samples, but it only makes up around 0.2 percent. That suggests that scientists may need to rethink the way materials travel from one part of the surface to another after a meteorite impact. Or, at least, in this newer region.

Chang’e 5 collected its samples in the Mons Rümker region, an isolated volcano located in the northwestern part of the Moon’s near side, in the northern part of Oceanus Procellarum. Its main peculiarity is that it presents a concentration of 302 lunar domes, a series of rounded bulges at the top, which in many cases have a small crater at the top. They are believed to be the result of lava erupting through localized groups of vents, followed by relatively slow cooling.

These and the other samples collected in previous programs are crucial to learning more about the evolution of the lunar surface and where landing sites should be located for future human missions.

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