China Returns First-Ever Samples from the Moon’s Far Side

China’s Chang’e 6 spacecraft has successfully brought samples from the far side of the moon back to Earth, marking the first-ever return of materials from this scarcely seen lunar region. The historic feat signals not only China’s soaring ambitions as a rising space-exploration superpower but also the next phase of a new space race with the U.S. and its allies to establish outposts at the strategically valuable lunar south pole.

Wrapping up Chang’e 6’s 53-day mission, the spacecraft’s sample-return capsule parachuted down to a preselected site in the rolling grasslands of China’s Inner Mongolia Autonomous Region on June 25 at 2:07 A.M. EDT. Packed inside the capsule are approximately two kilograms of rock and soil that were scooped or drilled from the surface and subsurface of Chang’e 6’s lunar landing site in the northeastern quadrant of the moon’s South Pole–Aitken (SPA) Basin. Thought to have been gouged from the moon’s crust and underlying mantle by a giant impact more than four billion years ago, the 2,500-kilometer-wide SPA Basin is one of the largest and oldest craters in the solar system. Samples from its depths could help solve numerous lunar mysteries—chief among them the enigma of why the moon’s far side is so relatively bereft of the craters and vast plains of frozen lava that are strewn across the Earth-facing near side.

Chang’e 6 was China’s second lunar sample-return mission, as well as its second landing on the far side, following the far-side touchdown of Chang’e 4 in 2019 and the retrieval of near-side samples by Chang’e 5 in 2020. No other nation has landed on the far side, let alone gathered specimens there. That makes Chang’e 6’s batch of rocks and soil a hot commodity for scientists around the globe who are vying for a chance to study them.

Opening the Treasure Chest

One of those eager researchers is James Head, a research professor emeritus at Brown University and an éminence grisein global planetary science. Head earned his stripes in the 1960s by scoping out near-side landing sites and training moonwalking astronauts for NASA’s Apollo program. And today he relishes his collaborations with China’s burgeoning planetary science community.

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China is a relative newcomer to interplanetary missions, Head says, noting that the nation historically has mounted more astrophysics-focused space science. But thanks to heavy, sustained investments, China is now a major player in planetary science, having already successfully sent an orbiter and rover to Mars while also pursuing an asteroid rendezvous mission in addition to its lunar explorations. China, he says, is sparing no expense in efforts to capitalize on its precious lunar samples.

“I’ve been in the receiving lab in Beijing in the National Astronomical Observatories of the Chinese Academy of Sciences, where they’ll do the preliminary analysis of Chang’e 6 lunar samples. It is first-class; it’s all new,” Head says. “It’s the same with the Chinese Academy of Sciences’ Institute of Geochemistry in Guiyang. You practically have to crawl over the crates that are coming in, loaded with state-of-the-art equipment.”

The SPA Basin, Head says, is “like a treasure chest of coins from different parts of the moon, represented by individual fragments sent there by distant far-side impacts, with those fragments probably very different from one another.” And although the entire SPA Basin itself is estimated to be some 4.26 billion years old, Chang’e 6’s chosen landing spot within—at the smaller, circa 2.5-billion-year-old Apollo crater—should offer an especially sweeping overview of lunar history.

“So we’re looking for ancient ages of the rocks thrown in from other parts of the SPA Basin or excavated as part of the [younger] Apollo crater ejecta,” Head says. “It’s a bit like putting together a jigsaw puzzle where you might not even have all the pieces, and they might be from different puzzles.”

Science aside, Head says, the more meaningful message of China’s lunar-sampling success is that the nation is prepping for even more ambitious projects. “Each step that they do for these sample-return missions from the moon, they exercise command and control and other techniques you need to go do similar things other places, like carrying out a Mars-sample-return endeavor. They are definitely thinking ahead to that.”

Racing to the Moon

China has also announced its intention to land humans on the moon by 2030—a time line rivaling that of the U.S., which plans to send astronauts to the lunar surface as early as 2026 via NASA’s much-delayed Artemis program.

Both the U.S. and China are targeting the resource-rich lunar south pole for their future crewed missions, and each is presently shoring up additional support for its respective program by establishing partnerships with other nations. In collaboration with the U.S. Department of State, NASA’s Artemis Accords initiative has so far netted 43 signatory nations, each endorsing a common set of principles that are not legally binding and that the U.S. says support sustainable civil space exploration. China, together with Russia, is orchestrating an International Lunar Research Station, or ILRS, which it has declared will be “open to all interested countries and international partners.”

While specifics are sparse, Wu Weiren, chief designer of China’s lunar exploration program, outlined the broad ILRS plan while attending a national space conference last April.

At the conference, Wu said the first phase of the ILRS construction project involves building a “basic station” by 2035 in the lunar south pole region to begin pilot experiments utilizing local resources there. Water ice preserved in the shadowy floors of craters, for instance, could be processed into potable water—or into rocket fuel. The second phase of the ILRS will see expansion of this basic station and is projected to be completed by 2045.

Wu stated that the basic ILRS will benefit from a sequence of additional precursor lunar robotic missions following Chang’e 6. Slated for launch in 2026, the Chang’e 7 mission will survey for water ice and other resources in the vicinity of the lunar south pole, while the Chang’e 8 mission planned for 2028 will carry out tests aimed at on-the-spot utilization of lunar resources.

Sample-Science Diplomacy

NASA’s chief Bill Nelson has repeatedly flagged China’s flourishing lunar activities as a worrisome sign of a heated new space race akin to the frenzied competition between the U.S. and the former Soviet Union during the cold war. He did so during an April 30 House of Representatives hearing on NASA’s fiscal year budget for 2025.

“They say that they want to put international contributions into an experimental place on the south pole of the moon. Of course, my concern is that they don’t get there first and then say, ‘This is our area; you stay out,’” Nelson said.

The south pole of the moon is important, Nelson told U.S. lawmakers, “because we think that there is water there. And if there’s water, then there’s rocket fuel—and that’s one reason we’re going to the south pole of the moon.” Because of the moon’s lower gravity—a mere one sixth of Earth’s—rocket fuel produced there can be used far more efficiently to power voyages to destinations throughout the entire solar system.

Although overall U.S.-China relations appear unlikely to thaw anytime soon, in the particular case of China’s lunar samples, there are promising signs of potential research opportunities for U.S. researchers. Under a law passed in 2011, NASA is forbidden from using its funds for direct bilateral collaborations with China or Chinese-owned companies, but the space agency has pursued “multilateral” sample-study arrangements involving researchers from other nations, which the 2011 law does not explicitly prohibit.

Contacted by Scientific American on the matter, a U.S. State Department spokesperson says the State Department is working with NASA to enable access to China’s lunar samples.

“This engagement is guided by the scientific value of samples from novel regions of the moon and underscores the importance of transparency and the release of scientific data—key principles of the Artemis Accords,” the spokesperson says. “We are aware that as part of the application process, the China National Space [Administration] recently interviewed international loan applicants but has not announced selections.”

This development in the Chinese sample-return and analysis program is a great step forward in helping to promote “science diplomacy,” says Bradley Jolliff, director of the McDonnell Center for the Space Sciences at Washington University in St. Louis. “I will certainly be among those hoping to request and receive some of the Chang’e 6 samples for analysis.”

A Gateway to the Universe

Despite such modest diplomatic successes, however, the simmering off-world competition between the U.S. and China seems set for an eventual boiling point, with nothing less than dominion over the moon and beyond potentially in play.

“Given China’s behavior on Earth, there is a good reason to worry about whether they might try to exclude others from areas where they land and establish a presence, like the polar area that has a good chance of water ice,” says Dean Cheng, a senior adviser on China for the United States Institute of Peace in Washington, D.C. Another concern, Cheng says, is that China might be first to deploy a lunar positioning, navigation and timing system—a development that could confer major advantages in establishing standards for lunar activity, akin to the U.S. Global Positioning System (GPS) of satellites that underpins much of modern life here on Earth.

Although the United Nations Outer Space Treaty, which the U.S. and China have both ratified, declares outright that no nation may claim lunar territory and that all shall have free access to all parts of the moon, the treaty also presupposes the development of lunar infrastructure and requires that “due regard” be given to the interests of others.

“This language, despite itself, creates a ‘first mover’ advantage,” says space lawyer Michelle Hanlon, executive director of the Center for Air and Space Law at the University of Mississippi and co-founder of the nonprofit corporation For All Moonkind. “Whoever sets up shop first will have the right to require others act with ‘due regard’ to their positions.” “Due regard,” in such cases, could entail wide restrictions on lunar operations by other nations or private companies because of potential interference with delicate scientific observations or the hazardous effects of rocket-lofted moon dust. Anyone building lunar infrastructure—the U.S. included—could aggressively use this loophole to stake a claim to the moon’s water-rich regions.

That means this new race to the moon is not simply about sending humans there, Hanlon suggests, but rather to secure territory and to access lunar water for fueling missions to Mars and beyond.

The moon, Hanlon says, is “a strategic gateway to the rest of the universe”—a low-gravity proving ground for building and nourishing an off-Earth human presence using local materials. Given the hunger for limited lunar resources, she says, the real question is whether the law—if not the moon itself—allows room for two or more independent and competing outposts. “That’s something we don’t yet know,” Hanlon concludes.