June 28, 2024: This article was updated to add details about the lunar sample that were announced after its original publication date.
China brought a capsule full of lunar soil from the far side of the moon to Earth on Tuesday, achieving the latest success in an ambitious program to explore the moon and other parts of the solar system.
The sample, retrieved by the China National Space Agency’s Chang’e-6 lander after a 53-day mission, underscores China’s growing capabilities in space and marks another victory in a series of lunar missions that began in 2007 and have moment executed almost flawlessly.
“Chang’e-6 is the first mission in human history to return samples from the far side of the moon,” Long Xiao, a planetary geologist at the China University of Geosciences, wrote in an email. “This is an important event for scientists around the world,” he added, and “a cause for celebration for all of humanity.”
Such sentiments and the prospect of international exchanges of lunar samples have fueled hopes that China’s robotic missions to the Moon and Mars will serve to advance scientific understanding of the solar system. Those odds are contrasted by views in Washington and elsewhere that Tuesday’s achievement is the latest milestone in a 21st-century space race with geopolitical overtones.
In February, a private American spacecraft landed on the moon. NASA is also pursuing the Artemis campaign to return Americans to the lunar surface, although its next mission, a flight of astronauts around the moon, has been delayed by technical problems.
China, too, is seeking to expand its presence on the moon by landing more robots there, and eventually human astronauts, in the coming years.
In moving toward that goal, he has taken a slow and steady approach, executing a program of robotic lunar exploration that he had conceived decades earlier. Named after the Chinese moon goddess Chang’e (pronounced “chong-uh”), the program’s first two missions orbited the moon to photograph and map its surface. Then came Chang’e-3, which landed on the lunar side in 2013 and deployed a rover, Yutu-1. It was followed in 2019 by Chang’e-4, which became the first vehicle to visit the far side of the moon and put the Yutu-2 rover on the surface.
A year later, Chang’e-5 landed, sending nearly four pounds of lunar regolith to Earth. The achievement made China only the third country—after the United States and the Soviet Union—to achieve the complex orbital choreography of collecting a sample from the moon.
According to Yuqi Qian, a lunar geologist at the University of Hong Kong, the Chang’e-5 and Chang’e-6 maneuvers are both test runs for China’s future crewed missions to the moon, which, like the Apollo missions of the 1960s and 1970s, must land and then launch humans from the lunar surface.
While working toward putting astronauts on the moon, China’s long-term strategy has scientific benefits for understanding the solar system.
The Chang’e-5 sample was younger than lunar material collected by the Americans or Soviets in the 1960s and 70s. It is mainly composed of basalts, or cold lava from ancient volcanic eruptions.
Two Chinese-led research groups came to the conclusion that The basalts were about two billion years old, suggesting that volcanic activity on the moon extended at least a billion years beyond the time frame inferred from the US Apollo and Soviet Luna samples.
Other studies of the material ruled out theories of how the moon’s interior had heated enough to generate volcanic activity. A research team were found that the amounts of radioactive elements inside the Moon, which could decay and produce heat, were not high enough to cause the explosions. Other result ruled out water in the mantle as a possible source of interior melting that led to volcanism.
Chang’e-6 launched on May 3 with even bigger scientific ambitions: to bring back material from the far side of the moon. The near side of the moon is dominated by wide, dark plains where ancient lava once flowed. But the far side has fewer of these plains. It also has more craters and a thicker crust.
And because this half never sees Earth, direct communication with landers on the far side of the Moon is impossible, making a successful approach difficult. The Chinese space agency relied on two satellites it had previously launched into lunar orbit, Queqiao and Queqiao-2, to stay in touch with Chang’e-6 during its visit.
The spacecraft used the same technique as Chang’e-5 to reach the moon and then return its sample to Earth.
After a few weeks in lunar orbit, Chang’e-6 descended to a location on the edge of the South Pole-Aitken Basin, the oldest, deepest impact crater on the moon. Equipped with a mechanical scoop and a drill, the lander spent two days collecting lunar rock and dust from its environment and the subsurface of the moon.
He then hid the material away. The mission deployed a tiny rover that took a photo of the landing with a small Chinese flag raised. Then, on June 3, a rocket launched the sample container back into lunar orbit. The materials were then reunited on June 6 with a spacecraft that had remained in orbit and prepared to begin its journey back to Earth.
The sample canister re-entered Earth’s atmosphere at 1:41 p.m. local time, moving at speeds of about 25,000 miles per hour, according to Xinhua, a Chinese state news agency. His parachute opened about six miles above the ground.
The capsule, which burned up on its way through the atmosphere, landed in the Siziwang Banner region of Inner Mongolia at 14:07 local time. A Chinese flag placed near the pod fluttered in the wind as ground crews worked to recover the material.
The specimen weighed more than four kilograms, based on preliminary measurements. A mission spokesman told Xinhua on Friday that the soil appeared thicker and lumpier, compared to material previously recovered from the near side of the moon.
Qiong Wang, deputy chief designer of Chang’e-6 of the China National Space Administration, told Xinhua earlier in the week that part of the sample will be permanently stored. The rest will be distributed to researchers in China and abroad, he said.
When scientists conquer the far side soils, they will compare the composition of newly recovered basalts with those on the near side of the Moon. This can help them infer how the moon’s volcanic activity caused its two halves to evolve differently.
“New samples will inevitably lead to new discoveries,” Wei Yang, a researcher at the Chinese Academy of Sciences, told Xinhua. “Chinese scientists look forward to the opportunity to contribute to lunar science.”
The mission team will also search for material from the surrounding regions, blown away from their original locations by comet and asteroid impacts. If strong enough, these collisions may have excavated material from the moon’s lower crust and upper mantle, Dr. Qian said. This could lead to insights into the structure and composition of the lunar interior.
Molten rock from these impacts could also provide clues about the age of the South Pole-Aitken Basin and the era in which it formed, when scientists believe a barrage of asteroids and comets bombarded the inner solar system.
This period “completely changed the geological history of the moon”, Dr Qian said, and was also “a critical moment in the evolution of the Earth”.
Clive Neal, a planetary geologist at the University of Notre Dame, called the goals lofty, but looks forward to the discoveries that will follow the return of the sample. Referring to China’s streak of lunar success so far, “it’s outstanding,” he said. “More power to them.”
Strained political relations, however, will make it a challenge for American scientists to work with Chinese researchers to study the distant samples.
The Wolf Amendment, passed in 2011, prohibits NASA from using federal funds for bilateral cooperation with the Chinese government. Federal officials recently granted the space agency a waiver that allowed NASA-funded researchers to apply for access to the nearby sample recovered from Chang’e-5. But another bill passed the US House of Representatives in June it would ban universities with research ties to Chinese institutions from receiving funding from the US Department of Defense.
For the future, China has its eyes set on the lunar south pole, where Chang’e-7 and 8 will explore the environment and search for water and other resources. It hopes to send crewed missions to the moon by 2030. Eventually, China plans to build an international base at the South Pole.
NASA’s Artemis mission is also shooting for the lunar south pole. Bill Nelson, the space agency’s administrator, has previously referred to the parallel programs as a race between the United States and China.
Many scientists reject this framework. Resources for studying the moon dropped when American astronauts beat the Soviets to the lunar surface in 1969, Dr. Neal said. “I don’t like international space races, because they are not sustainable,” he said. “A match must be won. Once you win it, then what?’
He added: “I think it’s important to see space as something that can bring us together, rather than divide us.”
Several countries contributed payloads flown on the Chang’e-6 mission, including France and Pakistan. Chinese researchers saw this as a good sign for the future.
“Exploring the Moon is a shared endeavor for all of humanity,” said Dr. Xiao, adding that he hopes for increased international cooperation, “especially between major space transport countries like China and the United States.”
Joy Dong contributed reporting from Hong Kong.
