Last year’s Chinese lunar mission brought back the youngest rocks ever found on the moon, international researchers have found.
An analysis of the basaltic volcanic rocks collected by the Chang’e-5 probe last December concluded that they had been formed from magma from a volcanic eruption about 2 billion years ago – around a billion years later than the formation of the moon rocks that have previously been analysed.
The results confirmed what experts had long predicted based on remotely obtained images of the moon and showed that the moon was volcanically active later than expected.
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The findings were published in the journal Science on Friday by a team of 25 researchers from Australia, Britain, China, Sweden and the United States.
“There was an indication from remote observations that there are young basalts on the moon, but this is the first direct confirmation that they truly exist,” lead author Alexander Nemchin, a professor from Curtin University’s Space Science and Technology Centre in Australia, said.
“It also confirms that our remote observation techniques work, which is good news for people studying not only the moon, but also other planets, like Mars.”
The Chang’e 5 probe completed a 23-day mission in December and returned with the first moon samples in 44 years, making China the third country to do so after the United States and Soviet Union.
The samples collected during the Apollo and Luna missions were found to be more than three billion years old.
The latest mission brought back 1.7kg (3.74lbs) of rocks and dust from Oceanus Procellarum, or the Ocean of Storms, which was formed from solidified lava after an ancient volcanic eruption.
The region has high levels of heat-producing elements, including potassium, thorium and uranium, according to the article. They “generate heat through long-lived radioactive decay and may have sustained prolonged magmatic activity on the near side of the moon”.
But current analysis has yet to identify the heat source in the region that explains the late volcanic activity.
“There is no evidence for high concentrations of heat-producing elements in the deep mantle of the moon that generated these lavas, so alternate explanations are required for the longevity of lunar magmatism,” the research team wrote.
The international team worked remotely with a laboratory in Beijing to determine the age of the lunar rock samples using large mass spectrometers.
Nemchin said the next steps would be to try to understand how they were formed.
“We still need to explain the internal heat source that is responsible for the late melting of the interior on the planetary body that is small and expected to cool quickly,” he said.
“Heat producing elements is one of the first steps we would need to do to work out the mechanism of formation of young basalts,” he said. “A comprehensive chemical investigation in general will help to determine conditions at which these magmas form and point to a specific mechanism of formation.”
China is expected to launch its next robot lunar lander in 2024, with Chang’e 6 collecting samples near the lunar south pole before returning to earth.
The Chang’e 4 lander and rover, which were launched in late 2018, have been collecting data for more than 1,000 earth days on the far side of the moon.
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