The first analysis of lava samples from the far side of the Moon showed that volcanic eruptions occurred there 2.8 billion years ago.
The Moon is permanently turned to one side of the Earth, so exploring the invisible side of the moon remains a challenge. Only two Chinese landers have visited this part of the Moon.
The study, published on November 15 in the journal Science, is based on rock samples delivered to Earth by the Chang’e-6 lander in 2024. The mission delivered 1.9 kilograms of samples from the South Pole-Aitken basin — the first samples brought from the far side of the Moon.
Scientists from the Institute of Geochemistry in Guangzhou, led by Zexian Cui, studied the isotopes and chemical composition of the samples to determine their age and source. Isotopes are atoms of the same element that differ in the number of neutrons. The change in isotope ratios during radioactive decay helps determine the age of the samples.
Results of the study of samples from the far side of the Moon
The results have revealed that the lava from which the basalt formed is 2.8 billion years old. Previously, volcanism on the Moon has been dated to 2 billion years ago, but those conclusions were based on samples on the visible side. New evidence suggests that volcanic activity existed on the other side of the moon as well.
A study of Chang’e-5 lunar rover samples revealed that volcanoes could have erupted on the Moon even 120 million years ago, a time of the Late Cretaceous period when the Earth was still dominated by dinosaurs.
The samples also showed that the lava from which the basalt formed originated from a region of the Moon’s mantle with low levels of potassium, rare earth elements and phosphorus, elements found in lava on the visible side. This may be related to the impact crater that formed the South Pole-Aitken basin. The consequences of the impact were so catastrophic that they redistributed the rocks containing these elements and also melted the mantle directly beneath the impact site, depriving it of these elements.
The imbalance of elements also explains another interesting feature: large lava flows covering 30% of the visible side of the Moon, but only 2% of the back. The absence of elements such as potassium and uranium on the far side may explain the smaller amount of basalts, as these elements are radioactive and release heat as they decay. Their absence in the mantle on the other side of the Moon may be the reason for the lack of molten lava flows.
Earlier we reported on how unusual activity was recorded on the far side of the Moon.
Provided by Space
