What Studies On Soil Sample From Moon's Far Side Have Found

Volcanic rock in the sample collected by Chang'e-6, the first mission that brought back soil from the far side of the Moon, is about 2.8 billion years old, suggesting the landing site was volcanically active at the time, according to two new studies.

Chang'e-6 collected 1.9 kg of lunar soil via a robotic probe in June this year before returning to the Earth. In their first detailed analyses of lunar soil and rock from the Moon's far side, scientists said the eruption marked a recent episode of volcanic activity, previously known from samples taken by NASA's Apollo programme and Russia's Luna missions.

The two papers were published Friday in the journals Science and Nature.

Surprisingly, the basalt rock from the far side is young in comparison to the previously studied lunar near-side samples that aged more than 3 billion years, said Clive Neal, a professor at the University of Notre Dame and co-author on one of the two studies.

The near-side samples that Chang'e-5 of China collected in 2020 were analysed and found to be two billion years old.

The research showed the samples did not carry the signature of radioactive elements found in several Apollo-era samples.

“The relatively young age of the basalts (retrieved by Chang'e-6) is surprising along with the composition being practically devoid of radioactive elements,” CNN quoted Neal as saying. 

This “prompts the question ‘how and why were these magmas generated?'” he said. "The same question is still being asked about the Chang'e 5 basalts,” he added.

The co-author of the study said the initial analyses of the lunar soil samples further raise questions that can only be addressed in the time to come along with the study of additional samples.

Scientists from outside China can only apply to study these soil samples two years after the specimens' arrival on the Earth. This follows the precedent that NASA set during the Apollo missions.

Although the Apollo lunar flights ended in 1972, NASA says it continues to get nearly 60 research requests for samples every year. Using the Apollo data, over 2,500 scientific papers have already been published through 2015, the US space agency said.