The researchers found that around 99% of the basalt fragments collected at the landing site were from around 2.8 billion years ago, but they also found a sample that dated back 4.2 billion years, implying that volcanoes were active on the far side of the moon for at least 1.4 billion years.
Lunar samples returned to Earth by the Apollo, Luna and Chang’e-5 missions have established that volcanism took place on the nearside of the Moon between 4–2 billion years ago. However, the lack of samples from the farside means it has not been possible to confirm the timing of volcanic activity for that region. Earlier this year, the Chang’e-6 mission retrieved samples from the Apollo basin located in the north-eastern South Pole–Aitken basin, an area with the thinnest crust on the Moon, providing an opportunity to study farside volcanism.
The authors suggest this represents the age of the main volcanic episode at the Chang’e-6 landing site, which they note is a surprisingly young eruption and not recognized from observations taken from samples from the nearside of the Moon.
