-- Chang'e-5 is one of the most complicated and challenging missions in China's aerospace history, as well as the world's first moon-sample mission for more than 40 years. 

-- Comprising an orbiter, a lander, an ascender and a returner, Chang'e-5, with a total takeoff mass of 8.2 tonnes, is expected to bring about 2 kg of lunar samples back to Earth. 

-- To pave the way for manned lunar exploration and deep space exploration, the Chang'e-5 mission will use a sampling method different to those of the United States and the Soviet Union. 

-- The landing site of Chang'e-5 will be in the northwest region of Oceanus Procellarum, also known as the Ocean of Storms, on the near side of the moon.  

by Xinhua writers Yu Fei, Quan Xiaoshu, Zhou Huimin

China Tuesday launched a spacecraft to collect and return samples from the moon, the country's first attempt to retrieve samples from an extraterrestrial body.

A Long March-5 rocket, carrying the Chang'e-5 spacecraft, blasted off from the Wenchang Spacecraft Launch Site on the coast of southern island province of Hainan at 4:30 a.m. (Beijing Time).

A Long March-5 rocket, carrying the Chang'e-5 spacecraft, blasts off from the Wenchang Spacecraft Launch Site on the coast of southern island province of Hainan, Nov. 24, 2020. China on Tuesday launched a spacecraft to collect and return samples from the moon, the country's first attempt to retrieve samples from an extraterrestrial body. (Xinhua/Pu Xiaoxu) 

Chang'e-5 is one of the most complicated and challenging missions in China's aerospace history, as well as the world's first moon-sample mission for more than 40 years.

The mission will help promote China's science and technology development, and lay an important foundation for China's future manned lunar landing and deep space exploration, said Pei Zhaoyu, deputy director of the Lunar Exploration and Space Program Center of the China National Space Administration.

Chang'e-5, comprising an orbiter, a lander, an ascender and a returner, with a total takeoff mass of 8.2 tonnes, is expected to accomplish unmanned rendezvous and docking in lunar orbit, an unprecedented feat.

After it enters the lunar orbit, the lander-ascender combination will separate from the orbiter-returner combination.

While the orbiter-returner orbits about 200 km above the lunar surface, the lander-ascender will touch down on the northwest region of Oceanus Procellarum, also known as the Ocean of Storms, on the near side of the moon in early December.

Within 48 hours, a robotic arm will be extended to scoop up rocks and regolith on the lunar surface, and a drill will bore into the ground. About 2 kg of samples are expected to be collected and sealed in a container in the spacecraft.

Then the ascender will take off, and dock with the orbiter-returner in orbit. After the samples are transferred to the returner, the ascender will separate from the orbiter-returner.

When the geometric relationship between Earth and the moon is suitable, the orbiter will carry the returner back to Earth. The returner will reenter the atmosphere and land at the Siziwang Banner in north China's Inner Mongolia Autonomous Region.

The whole flight will last more than 20 days.

A Long March-5 rocket, carrying the Chang'e-5 spacecraft, blasts off from the Wenchang Spacecraft Launch Site on the coast of southern island province of Hainan, Nov. 24, 2020. China on Tuesday launched a spacecraft to collect and return samples from the moon, the country's first attempt to retrieve samples from an extraterrestrial body. (Xinhua/Zhang Liyun) 

PAVING WAY FOR MANNED LUNAR EXPLORATION

Pei said if the Chang'e-5 mission succeeds, China's current lunar exploration project would come to a successful conclusion.

Named after Chinese legendary moon goddess Chang'e, China's current three-step lunar exploration program, which began in 2004, includes orbiting and landing on the moon, and bringing back samples.

Through the program, China has acquired the basic technologies of unmanned lunar exploration with limited investment, said Pei.

China is drawing up plans for future lunar exploration. To pave the way for manned lunar exploration and deep space exploration, the Chang'e-5 mission will use a sampling method different to those of the United States and the Soviet Union, said Pei.

The United States sent astronauts to the moon to collect samples. In the Soviet Union's unmanned lunar sampling missions, the spacecraft took off from the moon and returned to Earth directly.

But China chose a complicated technological approach including unmanned rendezvous and docking in lunar orbit, which could bring back more samples and lay a technological foundation for manned lunar missions, Pei said.

"Unmanned rendezvous and docking in lunar orbit will be a historic first. It will be very difficult," said Peng Jing, deputy chief designer of the Chang'e-5 probe from the China Academy of Space Technology under the China Aerospace Science and Technology Corporation.

"We could call it a milestone mission. Its success will help us acquire the basic capabilities for future deep space exploration such as sampling and takeoff from Mars, asteroids and other celestial bodies," Peng said.

UNRAVELING MORE SECRETS

The scientific goals of the Chang'e-5 mission include the investigation of the landing area to obtain the on-site analysis data related to the lunar samples, as well as systematic and long-term laboratory analysis of the lunar samples.

The landing site of Chang'e-5 will be to the west of that of Chang'e-3, which went to the moon in 2013.

This site is chosen because the region has a young geological age, younger than the sampling areas of the United States and the Soviet Union more than 40 years ago. This region has never been sampled. The new samples will be of great scientific value, said experts.

"Domestic and overseas scientists will all have a chance to get the lunar samples to be brought back by Chang'e-5 for research," Pei added.

Scientific instruments installed on the lander include cameras to survey the landing site and sampling area, an infrared spectrometer to detect the material composition of the sampling area, and equipment to probe subsurface structure.

Though lunar samples were brought back in U.S. and Soviet missions, scientists need more samples of different ages to piece together a complete history of the moon. "Chang'e-5 will give scientists a better understanding of its formation and evolution," Peng Jing said.

"We designed two methods for the spacecraft to collect samples. One is to sample the lunar surface, and the other is to drill underground. The two methods could increase the chance of getting more diverse samples," Peng said.

Lin Yangting, a researcher with the Institute of Geology and Geophysics under the Chinese Academy of Sciences, said lunar soil is like a book hiding the secrets about the sun, Earth and the moon. Researching lunar soil could lead to better understanding of the solar system and Earth.

"Research on lunar soil is a necessary basis for the construction of lunar bases and exploitation of the moon in the future," Lin said.

Chinese scientists are considering a scientific research station on the moon. Lunar resources will be utilized in the construction and operation of future lunar bases. For example, lunar soil can be used in building bases through 3D printing, Lin said.

China's Chang'e-4 probe, which landed on the far side of the moon in early 2019, is still working, and has made a series of scientific discoveries. "But we are looking forward to carrying out more detailed research on the lunar soil in laboratories on Earth. Chang'e-5 will help scientists realize this dream," Lin said.

Chang'e-5 will drill under lunar surface for samples recording evolutionary events, and grab lunar soil and probably rock fragments. Using modern analytical technologies, scientists will be able to unravel the mysteries of volcanic activities and meteorite impacts over the past billion years, Lin said. (Xinhua)