China News Service, Beijing, September 17 (Mar Shuaisha Guo Chaokai) On the 17th, the Shenzhou 12 manned spacecraft landed safely on the Dongfeng landing site.

This is the seventh manned flight carried out by the Shenzhou manned spacecraft. It went through three stages of braking flight, free gliding, re-entry, and landing.

Braking flight and free coasting phase: Carry out the first radial rendezvous and docking technology verification

  When the three astronauts entered the Shenzhou 12 manned spacecraft, the spacecraft began to separate from the space station's core module, and flew from the forward docking interface of the core module to the rearward docking interface, and then to the radial docking interface.

According to Shao Limin, deputy chief designer of the Shenzhou 12 manned spacecraft of the Fifth Academy of China Aerospace Science and Technology Corporation, this is for the on-orbit technical verification of the Shenzhou 13 radial rendezvous and docking.

  Shao Limin said that during the return flight phase, the orbital module is first separated from the return module and the propulsion module. The combination of the return module and the propulsion module reduces the flight speed through braking and deceleration, and is gradually pulled away from the original flight orbit by the gravity of the earth and enters freedom. Taxiing stage.

After that, the propulsion module and the return module are separated, the return module enters the earth's atmosphere at an accurately calculated reentry angle, and the propulsion module burns when it crosses the atmosphere.

Re-entry phase: the "black barrier" time of loss of communication

  The shape of the Shenzhou 12 return capsule is like a "big bell" with a narrow upper and a wide bottom. Through the adjustment of the attitude of the engine, it returns to the earth in a lift-like manner with the outsole facing forward.

When entering the atmosphere, the return capsule violently rubbed against the atmosphere at a speed of several kilometers per second, igniting a high-temperature flame of more than 2,000 degrees.

  During the landing process, the gas and the ablated heat-resistant material on the surface of the return cabin are ionized to form a plasma zone that wraps the return cabin, which greatly attenuates the radio communication between the return cabin and the outside world, and causes the radio communication between the ground and the spacecraft. Interruption, this period of time is called the "black barrier zone".

In this process, the ground cannot control the spacecraft through any remote control method, and rely on the aircraft to handle the state automatically.

Landing phase: multiple buffers, low speed landing

  At an altitude of about 40 kilometers from the ground, Shenzhou 12 has basically left the "black barrier zone". When it continues to decelerate until it is about 10 kilometers away from the ground, the static pressure altitude controller on the return cabin judges by measuring the atmospheric pressure At the altitude, the guide parachute, the deceleration parachute, and the main parachute are opened successively to ensure that the return capsule can achieve multiple decelerations in a softer manner and prevent the astronauts from receiving excessive impact at one time.

  When the spacecraft is about to land, the thrust reverser engine installed at the bottom of the return cabin performs reverse ignition to ensure that the return cabin decelerates to less than 2 meters per second at the end.

At the same time, the astronaut seat with cushioning function starts to lift automatically before landing, so that the energy of the impact is absorbed by the cushion.

Yang Haifeng, head of the overall flight control of the Shenzhou 12 manned spacecraft of the Fifth Academy of Aerospace Science and Technology Group, described this moment as a "thrilling and critical moment."

  The Shenzhou 12 manned spacecraft triumphed in the flames, once again realizing the feat of Chinese astronauts traveling back and forth between heaven and earth.

After five years of hard work, the Shenzhou team gathered at the place where the Dongfanghong-1 rose, and successfully completed the key missions of the space station stage.