First Chinese Sample-Return Lunar Mission

China became the third nation to bring back a soil sample from the Moon

Chinese space program started soon after the Korean war. As in the Soviet Union and the US, it began with the development of short-range ballistic missiles. After the successful reverse engineering of Soviet ballistic missiles, China began developing original rocket designs. Rocket-launching infrastructure grew, and ever-more-powerful ballistic missiles lifted-off from the budding spaceports.

In the late 60s, China officially began developing the crewed space program. China successfully launched its first satellite, Dong Fang Hong 1 (“East is Red” named after a revolutionary song). After the death of Mao Zedong, multiple space projects were abolished and the progress slowed. Until the 1990s, the Army exclusively directed the space activities. In 1993, China National Space Administration (CNSA) was established, which oversees the planning and execution of the Chinese space program.

Human spaceflight is under the umbrella of the Shenzhou program, which has begun in 1992. In 2003, China launched its first taikonaut (Chinese astronauts, from tàikōng for space) into space. Yang Liwei’s twenty-one-hour flight marked China as the third country with a human spaceflight-capable program. Following the development trajectory of rival space-faring nations, China continued with spacewalks and more complex crewed missions.

In 2011, the first Chinese space station Tiangong-1 began orbiting the Earth. After an autonomous docking with Shenzhou 8, two crewed missions followed. China’s first female astronaut Liu Yeng was part of the crew of Shenzhou 9, which resided on the station for a bit more than a week in 2012. Followed by another crewed mission a year later that lasted fifteen days, the station burned in the atmosphere in 2018. Space station Tiangong-2 commenced operations in 2016 and was occupied by a single crewed mission before its deorbiting in 2019. These missions have paved the road towards the planned modular space station, similar to the International Space Station.

Soon after the first crewed mission, China National Space Administration began to focus on the exploration of the Moon.

Chinese lunar exploration program

Legends from the old mythologies often revolve around heavenly bodies, mostly Sun and the Moon. Chinese mythology is no different. Chinese Lunar Exploration Program is named after the goddess of the Moon: Chang’e. Celebrated during the annual “Mid-Autumn Festival,” legend describes the goddess escaping to the Moon after drinking her husband’s elixir of immortality and residing there ever since.

Landing on the Moon provides immortality in the history of space exploration. Chang’e program started in 2003–4. By the end of 2007, Chang’e 1 orbited the Moon, followed by Chang’e 2 three years later. In 2013 and 2018, two landers with rovers followed. Chang’e 4 was the first probe to soft-land on the far side of the Moon, which required an additional lunar satellite to keep the lander connected to the Earth stations.

Sample return mission was next.

Chang’e 5: sample return

Bringing the lunar sample back to Earth symbolizes the prowess of space technology. It combines the raw power of rocket engineering with the high precision of space navigation. Many technologies need to be orchestrated perfectly for the mission to succeed. Apollo 11 was the first to bring a Moon sample back to Earth, followed by Apollo 12. Soviet Luna 16 in 1970 executed the first fully-robotized mission and brought back more than a hundred grams of lunar soil. While overshadowed by NASA’s monumental achievement, Soviet accomplishment certainly tiled the path for the future exploration of other extraterrestrial objects.

Equipped with modern technology, China aimed to redo the achievement of the Soviet Union: bringing the soil sample back to Earth. Engineering of the probe and devising of the mission profile began in 2011. By 2015, the scientists started building the space probe, initially scheduled for launch in 2017.

Launched in 2014, Chang’e 5-T1 was a dress rehearsal for an actual sample return mission that tested multiple systems and re-entry capsule. Using the free-return trajectory, it traveled to the Moon, which curved its trajectory back towards the Earth. It performed a skip-reentry maneuver, in which the capsule first plunges into the atmosphere at high-speed, “bounces off” (similar as in stone skipping), and later reenters at a lower speed. A successful mission opened the doors for Chang’e 5, which would bring the lunar sample back to Earth.

Probe Chang’e 5 has left the Earth on top of the Long-March rocket on November 24, 2020. Named after the Long March of the Red Army of the Communist Party of China in 1934–35, Long March 5 rockets are heavy-lift launch vehicles. Chang’e 5 mass at launch was around 8.2 metric tonnes and was composed of four different modules: an orbiter, lander, ascender, and re-entry capsule (see figure above).

A few days after launch, the Chang’e 5 performed a 17-minute burn that slowed it down and positioned the probe into the lunar orbit approximately 400 km above the surface of the Moon. After the orbital correction, the probe stayed in a circular orbit. Like the Apollo mission, the separate lander detached and left to land on the Moon, while the re-entry capsule and orbiter remained in the lunar orbit.

Landing and the sample collection

The lander touched down as the third spacecraft to land on the Moon in the 21st century. The probe landed north from the Mons Rümker volcanic formation. This mountainous region rises roughly 1.3 km above the neighboring plains of the Oceanus Procellarum (Ocean of Storms) on the northwest of the Moon’s near side.

The probe landed in a geologically “younger” area of the Moon, formed in volcanic eruption approximately 1.3 billion years ago. Samples collected from such regions should shed light on the more recent geological past of the Moon and its volcanism. After landing, the probe drilled a hole into the lunar surface and collected the soil sample from the depth of approximately two meters. Additionally, its robotic arm scooped more material from the soil surrounding the lander. The samples were collected in a container in the ascend module. Besides, the lander also put a Chinese flag onto the lunar surface.

On December 3, the ascend module lifted off, leaving the descend module on the lunar surface. Upon entering into the lunar orbit, the automatic rendezvous maneuver took place, during which the ascend module and the orbiter joined. This docking was the first automatized docking in the lunar orbit. The soil samples were moved into the re-entry module, and the ascend module separated and crashed into the Moon. Soon after, the probe left the lunar orbit and headed for the Earth.

Return to Inner Mongolia

Upon reaching the altitude of 5,000 km above the Earth, the re-entry capsule separated from the rest of the orbiter module. Traveling at more than forty-thousand kilometers per hour, the re-entry capsule “bounced off” the upper atmosphere. During the re-entry that followed, it slowed down enough for parachutes to open. The Chang’e 5 landed in the Siziwang Banner of Inner Mongolia and — simultaneously — in the history books.

It brought back nearly two kilograms of soil samples. This sample is the first lunar sample after more than forty years. Chinese Academy of Sciences will begin the investigation of the samples at its National Astronomical Observatory. China will make the samples available to the international scientific community. The probe also carried various plant seeds, which will undergo an investigation to determine the effects of zero gravity and space radiation on crop yields.

Successful Chang’e 5 mission precedes other robotic missions. Future missions will focus on the exploration of the Moon’s south pole, where the potential crewed mission might be heading.

China has reached an important milestone. Not only it demonstrated its space exploration capabilities, but it also showed that the Chinese space ambitions remain intrepid. Operating in near isolation, China has advanced its presence in space, and it steadily adds various achievements to its list of space milestones. It is unclear whether the large-scale international collaboration will come to fruition any time soon and — if it does — to what extent. One opportunity for international projects is the planned space station. In the more distant future, international cooperation could lead to a joint lunar base.

Exploration of space has had a strong political tone from very early on. It demonstrates a pinnacle of the country’s technology and prestige. It also comes with a price tag that is often under question by the public. However, China’s budget for space exploration has surpassed Russia’s and is second behind the US. Continuing at this pace, China is becoming a nation with a formidable space infrastructure, and it will be exciting to see how it develops further.

Additional sources
Chang’e (Mythopedia.com)
Harvey B., Soviet and Russian Lunar Exploration [Springer-Praxis (2007)]
China’s Chang’e Program: Missions to the Moon (Space.com)
Chang’e 5 probe successfully enters lunar orbit (CNSA)
Chang’e 5 lands on moon, starts surface operations (CNSA)
Chang’e 5 set to start journey to Earth (CNSA)
Chang’e 5’s reentry capsule lands with moon samples (CNSA)
China Focus: Chang’e-5 bringing crops from space (XinhuaNet)
In space, the US sees a rival in China (phys.org)
China set to bring back first rocks from the Moon […] (sciencemag.org)

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