After conducting three successful robotic lunar missions between 2007 and 2013, China’s blossoming moon exploration program appears to be entering a slower, more tentative phase. The nation had intended to loft its Chang’e 5 spacecraft on a Long March 5 rocket by the end of the year, to land on and retrieve samples from the lunar surface. But a July launch failure of another Long March 5 has seemingly deferred those efforts for months—perhaps years. With the Chang’e 5 sample-return mission now unofficially but apparently on hold, China may instead next use a different rocket booster to send a lunar lander and rover to the moon’s far side in 2018. That separate mission is called Chang’e 4, and was built as a backup to China’s Chang’e 3 lander and Yutu moon rover that successfully reached the moon in December 2013.

Although disappointing for the China National Space Administration (CNSA), which hopes to eventually dispatch many more robotic probes to the moon and perhaps even human missions to its water ice–rich polar regions, the delay and reshuffling could ultimately prove beneficial by allowing more time for international collaboration to emerge on lunar science and exploration.

Many other nations—including, perhaps, the U.S.—are gearing up for their own visits to the moon in coming years, offering China plentiful potential partners in lunar exploration. More than 40 years have passed since NASA’s Apollo astronauts retrieved hundreds of pounds of moon rocks from their sorties on the lunar surface. And the last time any samples at all were returned to Earth was 1976, via some 170 grams sent back from the Soviet Luna 24 lander. New samples could be a scientific bonanza for the global lunar research community, but only if China proves willing to share.

Talks on potential collaborations and the sharing of lunar samples are already underway between Europe and China as well as early discussions involving China and Russia.

James Carpenter, a scientist at the European Space Agency (ESA) Directorate of Human and Robotic Exploration and a key player in a recent CNSA–ESA workshop on lunar samples in Beijing, says that “we in ESA are having exploratory talks with China about future cooperation in lunar exploration, and the science of sample analysis as a part of that.”

Similarly, China and Russia are on track to sign a bilateral agreement on joint space exploration from 2018 to 2022, with an emphasis on future missions to the moon and other deep-space destinations. “The Chinese clearly have a very ambitious program of lunar exploration operating on what can only be described as an ‘aggressive’ timescale,” suggests Ian Wright, a professor of planetary sciences at The Open University in the U.K. who also attended the lunar samples workshop. “What is not clear to me, at least, is how much of this [program] still needs [governmental] approval. But, I would put money on it all happening at some point,” Wright says. Although China’s lunar sample return might be delayed, he notes, the nation’s work on a facility to store and study those eventual samples is progressing at a rapid pace.

Needed: New Moon Rocks

For now, the greatest unknown may be the new launch date for Chang’e 5. According to Xingguo Zeng, a research assistant in the Lunar and Deep Space Exploration Division at the Chinese Academy of Sciences’ National Astronomical Observatories, the mission could launch as early as next year, but “the specific day is still unknown.”

Chang’e 5 is composed of four parts: the orbiter, lander, ascender and Earth-reentry module. The lander and ascender form a combination that would touch down on the lunar surface to prospect and collect samples using a drill and mechanical arm. Once the samples are secured, the ascender would blast off to transfer the moon material to the reentry capsule waiting in lunar orbit. The capsule would then rocket back to Earth, reentering the atmosphere and deploying parachutes to safely deposit its precious cargo back on terra firma. Finally, the samples would be transported to Beijing for processing, storage and study in a facility built and operated by the National Astronomical Observatories.

China would “of course” share its lunar samples with other nations, Xingguo says, “but the time when the samples would be released is determined by the China Lunar Exploration Program Administration committee, so it is unknown for us.”

That timing is unknown for NASA, too, according to Jim Green, head of the agency’s Planetary Science Division. NASA “is unaware of [China’s] plans to release samples to a broader planetary science community,” Green says.

The hunger for new samples comes from the fact that all the older returned lunar material came from just a handful of scattered sites that offer a woefully incomplete picture of the moon’s deep history. Scientists still lack a thorough understanding of exactly how Earth’s most intimate celestial companion formed billions of years ago. Chang’e 5 could help change that, by returning samples from Mons Rümker, a region in the moon’s Oceanus Procellarum crater thought to be rich in igneous rock much younger than the samples returned by the Apollo astronauts. Oceanus Procellarum is a prime example of a lunar “mare” (Latin for “sea”), a vast expanse of dark basalt that 17th-century astronomers mistook for a body of water on the moon.

“[Mons Rümker] is a great target for a sample-return mission as we have no Apollo samples from mare[s] less than roughly three billion years old, says Mark Robinson, a leading lunar expert at Arizona State University. Robinson is also the principal investigator for the camera system on NASA’s Lunar Reconnaissance Orbiter, which has been mapping the moon since 2009. “Hopefully, those young mare[s] are their target,” he says. Returning samples from that area would be “an awesome science return,” he adds, not only important for understanding the evolution of lunar volcanism over time but also for calibrating the moon’s exact age, which in turn helps constrain the ages of Mercury, Mars, Venus and other rocky bodies in the solar system.

Prohibitive Politics

Although China’s plans for studying and sharing Chang’e 5’s samples remain nascent, the nation has already offered sneak peeks of its under-construction laboratory to several outside researchers. David Blewett, a planetary scientist at the Johns Hopkins Applied Physics Laboratory, was one of the lucky few to preview the lab in summer 2016, during a visit sponsored by the Chinese Academy of Sciences.

To visit the underground facility you enter a ground-level elevator “and press minus 3,” says Blewett, who recalls seeing convoys of trucks delivering glove boxes and other equipment to the lab. “I can’t recall hearing or reading about plans for sharing the samples with the international community,” he says. If, however, the data-sharing follows the practices of past Chinese lunar missions, “there may be two proprietary periods for the data.” Scientists directly involved in the mission would have prioritized access, he says, followed by other outside researchers in China. Eventually, data were made available to researchers outside China via an internet database. A similar protocol might be used for data from Chang’e 5’s returned samples, he says.

Still, direct access to China’s cache of lunar materials is caught up in U.S. politics. At present the space agency and the White House Office of Science and Technology Policy (OSTP) are both prohibited from directly working with China due to a clause first inserted in 2011 federal budget legislation by Rep. Frank Wolf (R–Va.), who at the time chaired the House Subcommittee on Commerce, Justice, Science and Related Agencies. Wolf is now retired and left Congress in 2015 but a version of the “Wolf Amendment” remains in force to this day, and prevents NASA and OSTP from “bilateral” collaborations with China without explicit authorization from Congress. “Therefore, I expect that China will not be eager to share samples directly with U.S. scientists,” Blewett says. There are, he adds, various loopholes to circumvent Wolf’s restrictions: Bilateral U.S.–China collaborations are explicitly prohibited, but “multilateral” projects are not, allowing U.S. researchers to work on NASA-funded work with scientists in China—provided there are researchers from additional countries also involved. Furthermore, neither the National Science Foundation nor the National Institutes of Health are under similar restrictions on joint U.S.–China research, offering additional avenues for federally funded collaboration. Which means that, one way or another, the U.S. planetary science community would likely find a way to gain access to any new Chinese lunar samples from China.

“This is an exciting time for lunar science, and it is a shame that politics prevents U.S. scientists from being directly involved, says Clive Neal, a lunar scientist at the University of Notre Dame. “Likewise, it is a shame that Chinese scientists cannot request Apollo samples. Scientists will, however, continue to work together in order to better understand the moon, and hopefully bridge the gap politicians can’t.”

One Small Step toward Sharing

One intriguing proposal to boost the chances for U.S. access to China’s forthcoming samples comes from one of the last living moonwalkers, the Apollo 11 astronaut Buzz Aldrin, who was the second human to set foot on the lunar surface. Aldrin wants to arrange a lunar rock swap, of sorts—something similar to an arrangement made between the U.S. and the Soviet Union in the 1970s, when both nations shared samples from their respective lunar missions. “Sharing lunar samples between nations is good for science,” he says. “It’s good for country-to-country cooperation. And furthermore, it helps focus the exploration agenda of the U.S. and China as we return to the moon as a proving ground for sending crews to distant Mars. I believe it’s time to seek avenues of space cooperation with China—and exchanging specimens brought back from the moon is one of them.”

There is, in fact, already a historical precedent for sharing lunar samples with China: In 1970 Pres. Richard Nixon gave some of Apollo 11’s moon rocks to China as a goodwill gift. China was among 135 foreign countries that received tiny flakes of lunar material. But this meager amount barely scratches the surface of Apollo’s trove, the bulk of which remains carefully curated at a facility in NASA’s Johnson Space Center. All in all, between 1969 and 1972 the six Apollo missions brought back 842 pounds of lunar rocks, core samples, pebbles, sand and dust from the lunar surface. The Apollo expeditions returned 2,200 separate samples from six different exploration sites on the moon. Perhaps offering more of Apollo’s mother lode to China would encourage reciprocal sharing.

“In my view,” Aldrin says, “I would encourage the scripting of a formal plan to share the bounty from our respective moon exploration undertakings. It is ‘one small step’ that can be forged between China and the United States as we both stride outward into deep space.”