Jones reported before China recovered the samples from the Moon in late 2020 that China has undertaken its most complex and ambitious space mission to date with the launch of its Chang’e-5 spacecraft, which will attempt to do something that has not been done since the 1970s: bring pristine pieces of the moon back to Earth.
Chang’e 5 Landing Site
Aiming for the flat volcanic plain of Oceanus Procellarum, located on the near-side of the Moon at the Mons Rumker, this Chinese lander is tasked with sampling lunar soil and rock and launching the specimens back to Earth. On November 23 at around 3:30 p.m. ET, a Long March 5 rocket lifted off from Wenchang Satellite Launch Center, on the coast of China’s Hainan Island, carrying the 8.2-ton spacecraft. After separating from the rocket, Chang’e-5 will use its own thrusters to make the estimated four-day trip to the moon. The spacecraft will then release a lander that will touch down near a volcanic mound called Mons Rümker in the northwest region of the lunar near side. There, it will drill and scoop samples from the surface and store them in a protective capsule.
An ascent module on the lander will then launch that capsule back into orbit around the moon, hopefully carrying around 4.5 pounds of lunar material. Finally, the orbiting spacecraft will collect the capsule and return it to Earth, sending it on a high-speed reentry to land in Mongolia at the end of the roughly 23-day-long mission.
The returned lunar samples will “absolutely add new knowledge of the history of the moon,” says Long Xiao, a planetary scientist at the China University of Geosciences. Of particular interest is the moon’s volcanic activity, which scientists once thought lasted for a little more than a billion years following the moon’s formation 4.5 billion years ago. Now, scientists studying craters on the moon believe magma continued to erupt and flow in some regions until much more recently, erasing signs of some ancient craters and leaving behind younger volcanic rock. The rocks sent back by Chang’e-5 “will ask us to rethink about why and how the moon’s volcanic history lasted this long,” Long says.
First approved in 2004, Chang’e-5 is a long-anticipated chapter in China’s lunar exploration plans. The Long March 5 rocket, designed with this mission in mind, required numerous breakthroughs in rocket technology, built with China’s most powerful engines and a new structural design. The heavy-lift vehicle failed during its second launch in July 2017 due to an issue with one of the engine’s turbopumps, delaying Chang’e-5 by three years.
Now that the ambitious mission is finally on its way, China is making a bold step in the new global era of lunar exploration. “It seems like the spacefaring countries of the world now view the moon as a place for long-term exploration and potentially exploitation and settlement,” says John Logsdon, a space historian and professor emeritus at George Washington University's Space Policy Institute.
Youngest Lunar Samples
The last sample returned from the moon was delivered by the Soviet Union’s Luna 24 spacecraft in 1976. That mission sent back 170 grams (a little more than a third of a pound) of lunar material directly from the moon’s surface to Earth. Chang’e-5, however, will resemble the more complex Apollo missions—which collected 382 kilograms (842 pounds) of material in all—involving a rendezvous and docking maneuver in lunar orbit. However, the Apollo samples are all more than three billion years old. Chang’e-5 aims to collect samples that are less than two billion years old, Long says, so scientists will be able to study the late-stage volcanism that shaped the younger parts of the rocky surface we see today.
Mons Rümker, near which Chang’e-5 will land, rises about 3,600 feet above the moon’s Oceanus Procellarum (Latin for “Ocean of Storms”). Oceanus Procellarum is a plain of volcanic rock that formed from past magmatic activity, making up the largest of the dark basaltic plains—known as maria, or “seas”—that are visible on the surface of the moon with the naked eye. Some of the rock in this region is thought to be much younger than all other lunar samples.
The moon’s volcanic history is not the only mystery that Chang’e-5 will attempt to solve, however. The landing area allows for “all kinds of fundamental hypotheses to be tested,” says James Head III, a planetary scientist at Brown University. Looking at the mineralogy of the rocks and soils near Mons Rümker could help reveal why the region has an unusual and unexplained concentration of certain elements—potassium, rare earth elements, and phosphorus—and a strong radioactive anomaly driven by the elements thorium and uranium. “There are really good fundamental questions to be answered that will change our thinking about the moon big time,” Head says.
The mission could also help calibrate timescales across the entire solar system. Counting the size and number of craters in an area gives clues about the age of the site, because impact craters accumulate at an estimated rate over time. Dating lunar samples can provide more accurate ages not only for the moon’s surface, but also for other pockmarked objects across the solar system, which are often dated by comparing their surfaces to similarly aged regions of the moon. The new dating analyses “could potentially challenge theories and assumptions and pose new questions” about how our planetary neighborhood formed, says Clive Neal, an expert in lunar geology at the University of Notre Dame.
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