Just under two years ago, China, a relative newcomer to deep space exploration, pulled off something no other nation had ever done—the first successful soft landing on the far side of the moon. The car-size Chang’e-4 lander and a smaller rover named Yutu 2 touched down in the South Pole-Aitken basin, a giant impact crater believed to be the largest and oldest in the solar system. Named for a legendary moon goddess, the Chang’e-4 mission returned spectacular 3D images of the basalt-rich landing site, along with unique data on the basin’s geologic composition and electromagnetic environment.
Now, with its third moon lander, China plans an even more ambitious step—a robotic mission to collect samples of lunar soil and return them to Earth for the first time since the Apollo era. Launched on November 24 onboard a modified Long March 5 heavy lift rocket, Chang’e-5 is targeted to land autonomously in Oceanus Procellarum, the Ocean of Storms. Its goal is to collect two kilograms of rubble and dirt from a relatively young (less than two-billion year-old) region near Mons Rümker, a bulging mountain that rises 1,300 meters above the plain, surrounded by more than 20 rounded lava domes. The lander will use a drill and a robotic arm with a scoop to pick up material in its immediate vicinity—no rover this time—and will have just one lunar day, or two weeks on Earth, to complete its work.
The launch of Chang’e-5 was delayed nearly three years after a Long March turbopump malfunctioned in 2017, causing the rocket and its communications satellite to crash into the ocean a few minutes after liftoff. Next week’s launch should benefit from nearly three years of YF-77 engine redesigns and two successful Long March missions since the accident, including the launch of the Tianwen 1 probe to Mars last July.
Chang’e-5 will be the first lunar sample return since the robotic Soviet Luna 24 mission in 1976. But this mission is more than just a repeat, and will feature multiple innovations, including ground penetrating radar to reveal the substructure of Mons Rümker and a coring drill able to extract cores at least two meters deep with all layers preserved.
Most advanced of all will be the return to Earth, starting with the liftoff of Chang’e-5’s ascent vehicle and its store of core samples from the surface, followed by an automated docking with a service capsule in lunar orbit. The core samples will then be transferred to a return capsule, which will execute a “one-skip” reentry procedure upon arrival at Earth, bouncing off the upper atmosphere to slow down and enable a safe landing in Inner Mongolia’s Siziwang Banner, the same pastoral site where Shenzhou astronaut crews have landed. The return is planned for mid-December.
All these steps are deemed essential to China’s plans for future exploration of the moon, which include a small robotic lunar research station—possibly with international partners—scheduled for later this decade, followed eventually by astronaut landings.
“The Chinese are not naïve enough to say [these missions] are just for pride and prestige. They want to do good science,” says James Head, a professor of planetary geology at Brown University and coauthor of a 2018 paper on the geological setting for the Chang’e-5 mission. Head is a veteran planetary explorer, having collaborated on U.S., Russian, and Chinese missions going back to the Apollos and Lunas of the 1970s.
Why Mons Rümker? Head and his counterpart in China, Long Xiao, who’s with the Planetary Science Institute at China University of the Geosciences in Wuhan, say the region is anomalous, radioactive and uniquely unexplored. “A relatively smooth site [for landing] with controllable engineering is the first priority,” Xiao explained in an email. “But for science, we did not want to return the same or similar samples as the Apollo and Luna missions. The Rümker region was targeted [because] this is different from the previous landing and sampling sites and hasn’t been explored in situ.” Xiao suggests the volcanic deposits around Rümker may hold the key to understanding the moon’s origins and evolution.
The region where Chang’e-5 will touch down has half the impact craters and much more recent lava flows than either the Apollo 11 or 12 sites, which also were in flat plains. How can one part of the moon be so much younger than the other, and by billions of years? No one knows, exactly. Remote sensing suggests that the Rümker area has high amounts of radioactive thorium, which according to one model, may have heated up the moon’s mantle enough to form the basaltic flows. “That’s why Chang’e-5 is going there, [because] we need to bring back the samples and measure them,” explains Head, who teaches graduate students at the Chinese University of Geosciences at Wuhan during summers. Once the new samples are evaluated and dated, he says, “we can go back and calibrate the [age estimations] for other celestial bodies—Venus, Mars, and Mercury, for example—and that could change our thinking about all the planets over the last few billion years.”
The robotic Chang’e missions have been a great success for China’s evolving lunar program, which has solid government funding and multiple academic collaborations. “This is not a pedal-to-the-metal, go go go ‘let’s-put-a-person-on-the-moon [program],’” observes Dean Cheng, a senior research fellow for Chinese political and security affairs at the conservative Heritage Foundation in Washington. “There are many aspects to the Chinese program—major powers do science, for example—but also recognition that space benefits the Chinese economy” in areas such as advanced materials, systems engineering, power storage, communications technology, and radar. “If you do a lot of space things, you promote key industrial areas,” says Cheng.
As China builds its space program, it has already chalked up a number of firsts. In 2018 the country launched a lunar communications relay satellite, Queqiao (meaning “Bridge of Magpies”) positioned at a libration point behind the moon, which allowed Chang’e-4 to communicate with Earth from the lunar far side. “This is important because no other country has deployed an ‘application’ satellite [of this type],” Cheng says.
Is this part of a plan to somehow conquer the moon? Not likely, Cheng insists, since the country is a signatory to the Outer Space Treaty, which calls for the peaceful, shared use of space. “I don’t see the Chinese laying claim to the moon any more than the U.S. did with Apollo,” he says. But, like their counterparts in the United States and Europe, “certain elements in China are talking about an Earth-moon-space economy zone to develop and exploit.”
NASA will be following the Chang’e-5 mission closely, even though it is not a direct participant. “The key scientific advance…is simply the return of an actual sample from one more area of the moon…[and] every data point is valuable,” says David Williams, who heads the agency’s Space Science Data Coordinated Archive at the Goddard Space Flight Center. “Since there hasn’t been a sample returned from the moon since 1976, and only three samples ever returned robotically, this will be a good demonstration of using the latest technology…which will be a useful example for any country planning a lunar sample return mission after over 40 years.”
NASA plans to send its own small lander missions to the moon starting as early as next year, and has a stated—although highly optimistic—goal of landing astronauts by 2024. But China doesn’t see it as a race, and isn’t focused on “What are the Americans doing now?” says Head. “The leaders of the Chinese National Space Agency believe they’re building a silk road in space. From a leadership point of view, they’re doing the same thing as Apollo—planting a human on the moon and returning him safely at the end of the decade. But with the Chinese, it’s broader. [They’re] not perturbed by short-term [setbacks.] Culturally, it’s a long-term view of history.”
Live streaming coverage of the launch (in Chinese) is here:
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