China has become the first country to gather samples from the far side of the moon and bring them back to Earth in a landmark achievement for the Beijing space programme.
A re-entry capsule containing the precious cargo parachuted into a landing zone in the rural Siziwang Banner region of Inner Mongolia on Tuesday after being released into Earth’s orbit by the uncrewed Chang’e-6 probe.
The return of the lunar material wraps up a highly successful mission for the China National Space Administration (CNSA) amid a wave of interest in which space agencies and private companies will build instruments and bases on the moon and exploit its resources.
The Chang’e-6 mission, named after the Chinese moon goddess, blasted off from Hainan province in south China on 3 May and touched down on 2 June on the side of the moon that is never seen from Earth. The moon shows only one face to the Earth because it is tidally locked and completes one full rotation in the time it takes to circle the planet.
The mission’s lander spent two days collecting rock and soil from one of the oldest and largest craters on the moon, the 1,600-mile-wide South Pole-Aitken (SPA) basin, using a robotic arm and drill. Its ascent module then lifted off from the moon’s surface and rendezvoused with the orbiter before embarking on its journey home.
“This is a great achievement by China,” said Martin Barstow, a professor of astrophysics and space science at the University of Leicester. “Recovering any samples from the moon is difficult, but doing so from the far side, where communications are particularly difficult is a step taken by no other agency. A real technological feat.”
The US, China and the former Soviet Union have gathered samples from the near side of the moon but China is the first to bring material home from the far side. The intention was to collect up to 2kg of moon rock and soil.
China previously collaborated with international scientists to study samples it brought back from the near side of the moon but it is unclear whether similar access will be granted to the new material from the far side.
The latest samples could shed light on longstanding mysteries in the early history of the moon and Earth. Ian Crawford, a professor of planetary science at Birkbeck, University of London, said dating the SPA was a “key objective” of lunar science because it would pin down the timeframe for lunar cratering.
Understanding the rate at which large asteroids battered the moon in its early history would shed light on the impact history of Earth, he added, as our home planet would be struck by the same kinds of asteroids at the same time. “Constraining this is important for understanding the impact regime under which life first appeared on Earth,” he said.
The collision that created the SPA basin may have scooped out enough rock to expose areas of the lunar mantle, which researchers believe is crucial to understanding the history, and potentially the origins, of the moon.
“It is possible that the SPA has excavated deep enough to expose the lunar mantle, and possible that fragments might be found in the Chang’e-6 samples,” Crawford said. “It’s long shot but it’s worth looking.”
The far side of the moon has fewer ancient lava plains or maria, a thicker crust, and because it is not shielded by Earth, sports more craters from violent impacts.
“Recovering samples from the far side is tremendously exciting scientifically, as we only have very limited information on the geology there,” Barstow said. “It has been processed very differently to the side of the moon facing us, which has been extensively resurfaced by volcanic activity in the past, creating the maria from which most samples have been obtained.”
China has more lunar missions planned this decade. They are intended to pave the way for an International Lunar Research base, which it will co-lead with Roscosmos, the Russian space agency, and the eventual landing of a Chinese astronaut on the moon.
Dr Simeon Barber, a senior research fellow at the Open University, said: “We’re entering a new era of discovery, and getting samples returned from the far side is a milestone achievement that will help us understand the geological history in that region, and why it differs so markedly from the more familiar near side.
“Specialised laboratories around the world have spent five decades finessing the analytical techniques to tease out the moon’s secrets from within near side samples returned by the Apollo and Luna missions. And now we are on the cusp of applying all that expertise to learn about the enigmatic far side of our nearest neighbour in space.”
