Moon was volcanically active more recently than thought
Samples of Moon rock collected by China’s Chang’e-5 mission have confirmed that lava was still flowing on our closest celestial neighbour as recently as 1.97 billion years ago.
The findings paint a picture of a much more dynamic subsurface compared to the mostly static Moon from the present era.
The Chinese National Space Agency have allowed international collaborators to access some of the material for analysis that it collected after touching down on the lunar surface in December last year. It is the first time any nation has collected rocks from the Moon since 1976.
Analysis from researchers at The University of Manchester determined that the basaltic volcanic rocks were two billion years old: one billion years younger than any other dated basaltic lava from the Moon.
They believe this presents a new mystery about how such a small rocky planetary body could retain enough heat to enable melting of its interior, and volcanic eruptions at its surface, two and a half billion years after it formed.
The lead researchers from the Beijing SHRIMP Center in China sorted through the material to pick out fragments around two millimetres in size which they then analysed by building upon a range of laboratory analytical techniques that were originally developed in the 1970s for the analysis of the first Apollo samples.
Dr Romain Tartese from The University of Manchester, said: “Continuous laboratory developments over the past decade, initially developed for analysis of lunar samples returned half a century ago by the Apollo missions, have allowed colleagues in China to extract crucial age information from these millimetre-sized particles scooped on the Moon’s surface.
“These young eruption ages are really exciting as it is a complete mystery how the interior of the Moon stayed hot enough to generate such young lava flows only two billion years ago.”
Dr Joshua Snape, a Royal Society University Research Fellow at The University of Manchester, said: “Samples like this allow us to not only understand the history of the Moon, but to also relate the age of the geological unit they were collected from to the number and size of impact craters that scar its surface. Combining these records helps us to calibrate the rates of impact cratering across the wider Solar System, helping us understand the geological records of other planetary bodies”
Co-lead international author Professor Alexander Nemchin, from Curtin University, said: “This was a truly international effort when having people in different time zones gave us ability to work on the project 24 hours a day, seven days a week. Some of us on the team still remember excitement of working with the samples nobody ever seen before from the Apollo era, others experienced this for the first time”.
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