China News Service, Wenchang, November 24th, title: Nine days of moon and galaxy broad: revealing the 3 key figures of Chang'e 5

  Author Guo Chaokai

  In the early morning of November 24th, Beijing time, China successfully sent the Chang'e-5 lunar probe into the Earth-Moon transfer orbit with the Long March 5 Yaowu carrier rocket at the Wenchang Space Launch Site. The launch was a complete success.

  This is the final battle of the three steps of China's lunar exploration project of "circumnavigation, landing, and return". It is also one of China's currently most technically difficult space missions with the most complex system composition; this mission will realize China's first extraterrestrial celestial body Sample return.

The reporter picked two, five, and six three key figures to reveal the secret of the Chang'e-5 mission.

  Collect about 2 kg of lunar soil

  The Chang'e-5 probe developed by the China Aerospace Science and Technology Corporation is one of the most complex spacecraft systems developed by China so far. It consists of four devices: an orbiter, a returner, a lander, and an ascender, and includes 15 sub-systems.

  In this mission, the Chang'e-5 probe will collect about 2 kilograms of lunar samples and return to Earth after more than 20 days of in-orbit flight.

The period includes 11 events including launch into orbit, earth-moon transfer, near-moon braking, round-moon flight, landing and descent, lunar surface work, lunar surface rise, rendezvous and docking and sample transfer, round-moon waiting, lunar-earth transfer, reentry and recovery, etc. stage.

  According to the China National Space Administration, the Chang'e-5 mission plans to achieve three major engineering goals: First, breakthrough key technologies such as narrow window multi-orbit binding launch, automatic lunar surface sampling and packaging, lunar take-off, lunar orbital rendezvous and docking, and lunar sample storage. Improve the level of China’s aerospace technology; the second is to realize China’s first automatic sampling and return of extraterrestrial celestial bodies to promote major progress in China’s science and technology; the third is to improve the lunar exploration engineering system and accumulate important personnel, Technology and material basis.

  Five "firsts" in China's space history

  The Chang'e-5 probe is China's first spacecraft to implement unmanned lunar surface sampling and return. This mission is expected to achieve five "firsts" in China's space history.

  ——Automatic sampling of lunar surface for the first time.

As one of the core keys of this mission, the automatic sampling and packaging of the lunar surface is the most eye-catching part of the Chang'e-5 mission.

The designer meticulously designed two "digging" modes for Chang'e-5: drilling and surface extraction.

  ——The first lunar surface takes off and rises.

The lunar surface environment is complex, and the lander is not necessarily in a stable state. It is likely to land on slopes or on different terrains such as bumps and depressions.

When taking off on the moon, it must rely on the spacecraft to "self-reliance" to achieve autonomous positioning and attitude determination during takeoff.

  -The first lunar orbital rendezvous and docking.

Chang'e-5 needs to fly to the lunar orbit, rendezvous and dock with the orbit-back assembly, and transfer the collected lunar soil to the returner.

After years of practical exploration, China has mastered the low-Earth orbit rendezvous and docking technology in the field of manned spaceflight, but the unmanned rendezvous and docking in the lunar orbit 380,000 kilometers away is not only the first time in China, but also in the history of human spaceflight. For the first time.

  -For the first time to take the lunar soil to reenter the earth at high speed.

The speed of the Chang'e-5 returner is close to the second cosmic speed of 11 kilometers per second.

Once the speed is too strong, the returner will head to the earth, the consequences are disastrous, so the returner must be slowed down.

The designers innovatively proposed a semi-ballistic jumping reentry and return technical solution, which is like flying water in space. The returner first enters the atmosphere at high speed, then jumps out of the atmosphere with the help of the lift provided by the atmosphere, and then pierces at the first cosmic speed. Enter the atmosphere and return to the ground.

  ——The storage, analysis and research of self-collected lunar samples for the first time.

The Chang'e-5 probe carries a variety of "artifacts", collects about 2 kilograms of lunar soil, seals them and sends them back to Earth safely.

For the first time, researchers will store, analyze, and research lunar samples taken by China.

  Six key links

  The technical difficulties of the Chang'e-5 probe mission are mainly manifested in the six key links of orbit design, lunar surface sampling and packaging, lunar surface take-off and ascent, lunar orbital rendezvous and docking and sample transfer, lunar ground incidence, and high-speed reentry and return of the earth’s atmosphere.

The flight procedures are very complicated and the technical performance requirements are strict. The development work is related to the success or failure of the third phase of China's lunar exploration project.

  Experts from the China Aerospace Science and Technology Corporation said that although China has mastered space rendezvous and docking technology, in the past the Shenzhou spacecraft and Tiangong-1 rendezvous and docking were carried out in the earth orbit about 400 kilometers away from the earth, and the Chang'e-5 probe will The rendezvous and docking of the ascender and the orbiter is completed on the earth's 380,000 kilometers of lunar orbit, and the assistance of navigation satellites cannot be used. This requires breakthroughs in the lunar orbit measurement and control accuracy, unmanned spacecraft rendezvous and docking technologies.

In addition, technical problems such as multiple separation surfaces of the combined body, high temperature control requirements, and high weight reduction pressure also brought new challenges to the development team.

  From project establishment to launch, the Chang'e-5 probe lasted 10 years.

Focusing on key core technologies and many difficulties and risks, the development team has successively broken through more than 20 key technologies involved in the lunar surface sampling mission, ensuring that the Chang'e-5 detector has a reasonable design and each functional performance meets the mission requirements.