China’s lunar mission Chang’e-5 has successfully retrieved rocks from the Moon – the first attempt to do so for nearly 45 years. Chang’e-5 was launched at 4.30 a.m. local time on 24 November 2020 by a Long March 5 rocket from Wenchang Satellite Launch Center. Once it landed on the Moon, it grabbed samples from the soil from an area not previously sampled to better understand the evolution history of our closest neighbour. The samples were returned to Earth in December 2020. 

Chang’e-5, weighing 8.2 tonnes, consists of four parts: an ascender, lander, returner and orbiter. Upon entering the Moon’s orbit, the ascender and lander separated and touched down in the Mons Rümker region – a volcanic mound in the north-western part of the Moon’s near side. The lander used a panoramic camera, spectrometer and ground-penetrating radar among other payloads to document the landing site before using a robotic arm to scoop up small rocks from the surface and drill up to 2 m into the ground.

The ascender then successfully lifted off from the top of the lander and docked with the returner-orbiter in orbit. The sample container was transferred to the returner, which headed back to Earth. “Chang’e-5 has achieved a number of ‘firsts’ in Chinese history, including sampling and taking off from another planet, and rendezvous and docking in the lunar orbit,” Pei Zhaoyu, mission spokesperson from the Chinese National Space Administration, told state media on 7 December.

Chang’e-5 also made more “firsts” on its way home. The probe was designed to adopt the so-called re-entry technology to slow down and avoid overheat by the Earth’s atmosphere. Much like skipping a stone on a lake, it dipped into the atmosphere, then jumped up, before finally making a gliding re-entry toward touchdown. China was confident about this method, having tested the technology with a rehearsal mission – dubbed Chang’e-5 Test 1. Indeed, Chang’e-5 was China’s most complex and ambitious lunar mission so far, so nothing was certain. Yet it successfully landed in Inner Mongolia, north China bringing with it about 1.7 kg of lunar material. Most of the returned samples will be stored at the National Astronomical Observatories of China, Chinese Academy of Sciences, in Beijing, with possible access by foreign scientists through collaboration with Chinese colleagues.

Rock collector

Brett Denevi from the Applied Physics Laboratory, Johns Hopkins University, who has analysed Apollo lunar samples, thinks that in Mons Rümker, China has picked “one of the best places to go” for a lunar sample-return mission. “That’s why this mission has attracted broad, international interest,” she says.

Indeed, scientists believe that part of Mons Rümker might have formed 1–2 billion years ago, being much younger than the sites visited by US and Soviet sample-return missions, which were more than 3 billion years old. Back in the 1960s and 1970s, six US Apollo crewed landings brought back 382 kg of rocks from the Moon while three Soviet Luna robotic missions returned 0.326 kg. The samples from the Chinese mission will help scientists improve their model to estimate the age of surfaces in the solar system, from rocky planets such as Mars and Mercury to asteroids. Surface ages are roughly defined by crater densities: more craters, older surfaces.

If the ages of Chang’e-5 samples are confirmed to be 1–2 billion years, it may challenge our current theory on the formation of the Moon, which should have cooled off by that time due to its small size and limited “heat budget”. Scientists would need to find out what had fuelled those volcanic eruptions. “[Chang’e-5] can lead to a whole new understanding of recent volcanisms on the Moon,” says Clive Neal from the University of Notre Dame in the US. “The new samples from Chang’e-5 will give us a way to quantify the younger end of the crater-counting curve.”

China is also working on multiple follow-up lunar missions, which will eventually lead to a human mission in the 2030s. These include Chang’e-6, which will return samples from the South Pole, while Chang’e-7 will perform a detailed survey of the south polar region. 

With renewed interest in lunar exploration and the advances in sampling and analytic capabilities, space-policy expert John Logsdon from George Washington University says that Chang’e-5 could “set a new standard” for robotic lunar exploration. “Chang’e-5 is an important step in the plan,” says Logsdon. “One that deserves close attention.”