Scientists continue to analyze rock and soil samples brought back by China’s Chang’e 5 lunar rover, and the latest results point to new types of geology in regions of the Moon that have yet to be discovered and explored.
Seven different types of rock have been identified among 1,731 kilograms (3,816 pounds) of 2 billion-year-old regolith – the loose, crumbly dirt and rubble on the Moon’s surface. One of the rocks is an entirely new type of lunar basalt, created at a time when the Moon was still volcanically active.
This regolith is the youngest to be brought back from the Moon to date, giving experts insight into a different time period than other samples and helping them chart a tumultuous period in our near neighbor’s history.
The seven rock types listed in the study are all considered “exotic” because they would have reached their current landing site from another location.
“In such a young geologic unit, a wide range of crustal components from various sources would be transported to the Chang’e-5 landing site by these latter ongoing surface processes on the Moon,” the researchers write. in their published article.
Some 3,000 particles smaller than 2 millimeters (0.08 inches) were sifted through by the researchers, as they searched for evidence of impact cratering and past volcanic activity. As on Earth, these types of igneous rocks can tell a geological story.
According to the researchers, three of the clasts exhibited unusual petrological and compositional characteristics. The high-titanium vitrophilic fragment — rich in titanium, with larger crystals embedded in glassy rock — has mineralogy we’ve never seen before on the Moon and likely represents a new type of lunar rock.
According to the study authors, these rock particles can be associated with sites on the Moon up to 400 kilometers (249 miles) from where they were picked up, thrown to the surface by a succession of impacts. asteroids over the millennia.
“These exotic igneous clasts would record lithological diversity and regolith gardening processes at [roughly 2 billion year old] young mare regions of the Moon,” the researchers write.
Put it all together, and the conclusion is that these fragments come from parts of the Moon’s surface that we don’t yet know about, in geological terms. There may even have been volcanic eruptions that we are not yet aware of.
However, only about 0.2% of the material in the samples was classified as exotic, instead of the expected 10-20%. This suggests that scientists may need to rethink how impact ejecta travel across the lunar surface, at least in this new region.
Chang’e 5 collected its samples from the Mons Rümker region north of the Moon’s Oceanus Procellarum, and other samples – as well as existing ones from past missions – will be useful in learning more about the evolution of the lunar surface and on the future. landing and base sites should be located.
The research has been published in natural astronomy.