It was December 1972. The three American astronauts from the Apollo 17 mission were returning to Earth. Clap of end of the program and beginning of a spatial disinterest. “Take the seismometers, there haven’t been any on the lunar surface since, so all the data we have goes back to the Apollo program”quotes Jessica Flahaut, specialist in lunar geology at the CNRS and the University of Lorraine. “As a result, we still don’t know for sure whether the Moon has a liquid or solid core. »
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Many other questions remain unanswered about our pale neighbor. Where did the strong magnetic field that existed in the past come from and why did it disappear? Why are the hidden side and the visible side so geologically different? And even, how exactly was this natural satellite born? “General consensus is that the Moon formed after a large object slammed into Earth, but its past evolution remains very unclear”recognizes Agnès Fienga, astronomer at the observatory of the Côte d’Azur.
Its present too: while we thought it was completely dry, the Moon actually contains water. With the evolution of the instruments, further analyzes of the samples brought back by Apollo showed an infinitesimal presence in the rocks, while in 2009 the Indian probe Chandrayaan-1 highlighted water ice at the level of the pole. South. This is where the next Artemis missions will go.
Learn about the Moon, Earth and the Universe
Agnès Fienga concedes it, “we can easily imagine it dead and dreary, but the Moon is a beautiful laboratory close to home which has so much to teach us”. On itself, but also on Earth. It is, for example, thanks to our nocturnal companion that scientists have understood the existence of “magma oceans”, which must have covered the surface of rocky planets like the Earth at the very beginning of their history.
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“Everything that has happened for 4.5 billion years is still inscribed on the lunar surface, unlike the Earth where the crust is constantly renewed by plate tectonics and volcanism”, recalls Jessica Flahaut. As summarized by Agnès Fienga: “The mechanisms that can be studied on the Moon are comparable to others in the solar system. »
Finally, in the longer term, the Moon could serve as a basis for studies of deep space. For example, installing on its hidden side an observatory in the field of X-rays, which would watch the Universe without interference. Fifty years after Apollo 17, it is therefore an understatement to say that the “lunar reconquest” delights scientists. Expectations are huge. And this, even if after the launch of the first mission in the spring, it will probably be necessary to wait until 2026 for astronauts to set foot on the lunar regolith.