China News Service, Beijing, September 17 (Mar Shuaisha Guo Chaokai) On September 17, the Shenzhou 12 manned spacecraft returned to Earth with three astronauts Nie Haisheng, Liu Boming, and Tang Hongbo, and landed smoothly on the Dongfeng landing site.
As the seventh manned flight performed by the Shenzhou manned spacecraft, some key "sacred operations" for manned return from space helped the success of this flight.
"Warm up" before returning to verify radial rendezvous for the first time
When the three astronauts closed the doors of the core compartment and entered the Shenzhou 12 manned spacecraft, the spacecraft began to separate from the space station Tianhe core compartment and began a "warm-up" action before returning.
After separating from the forward docking interface, the spacecraft flew along the designed arc to the rearward docking interface, and after a short pause, it flew to the radial docking interface again. This successfully verified the radial rendezvous technology and laid a foundation for subsequent manned flight missions. An important technical foundation.
Peng Huakang, the chief designer of the Shenzhou 12 manned spacecraft system of the Fifth Academy of China Aerospace Science and Technology Group, said that the "warm-up" is the spacecraft's autonomous judgment and flight by automatically measuring the relative position, relative attitude and angle of the space station.
Homecoming "track" design "step by step"
In the past, the manned spacecraft returned and landed on the grasslands of Siziwang Banner in Inner Mongolia, but this time the Shenzhou 12 manned spacecraft chose the east wind landing site in the Badain Jaran Desert.
According to Yang Haifeng, the person in charge of the overall flight control of the Shenzhou 12 manned spacecraft, the reentry capsule must enter the atmosphere at a fixed reentry angle. If the reentry angle is too large, the temperature outside the reentry capsule will be too high, and the reentry angle will be too small and too small. Will fly directly out of the atmosphere.
It can be said that this road home must be "step by step meticulous."
Therefore, the spacecraft's orbit design team carefully designed the return orbit plan and added predictive correction guidance methods to help the return module automatically calculate and maintain the reentry trajectory according to the real-time position, aerodynamic parameters, and aiming point deviations during the reentry process. The change of the landing point and the large range of orbital changes ensure that the "orbit" of the return is not bad at all.
Back to "posture" safe and comfortable
The return cabin is a bell-shaped design with a narrow upper and a wide bottom. After the propulsion cabin and the return cabin are separated, the return cabin will use its own engine to adjust its attitude and become a flying state with the outsole facing forward.
In this way, the return capsule generates a certain lift when it passes through the atmosphere, so it can control the flight trajectory to a certain extent, so as to ensure a high accuracy of the landing point and a relatively small overload impact on the astronaut.
Not only should the return capsule adopt a comfortable return posture, the astronauts should also "lie flat" in the seat at an angle almost parallel to the outsole. Choosing this posture to return is to better alleviate the impact caused by the deceleration of the spacecraft. So as to bring more protection to yourself.
"Heat protection jacket" builds life protection "firewall"
After the return capsule enters the atmosphere from space orbit, it will friction with the atmosphere at a speed of thousands of meters per second, forming a high temperature of thousands of degrees Celsius, and rushing to the ground like a burning fireball.
In order to ensure that the interior of the return capsule is always maintained at a suitable temperature, the structure and institutional development team of the Fifth Academy of China Aerospace Science and Technology Corporation has continued to research key problems and developed special heat-resistant materials for the return capsule of the manned spacecraft.
Liu Xiaozhen, the overall chief designer of the Shenzhou 12 manned spacecraft’s machinery, vividly referred to it as a "heat-proof jacket". The ablation-resistant material on the surface takes away a large amount of heat energy when it melts, evaporates and decomposes, preventing high temperatures from entering the cabin, ensuring The air temperature in the cabin is maintained at about 20 degrees Celsius. Although there is only a thin layer, it is a veritable "firewall" to protect the lives of astronauts.
Anti-vibration "combined boxing" guarantees landing
The landing process of the return module is a big challenge to ensure the safety of the astronauts. When the cabin is about 10 kilometers from the ground, the speed of the spacecraft has dropped below 330 meters per second. At this time, the static pressure altitude controller on the return module By measuring the atmospheric pressure, the altitude is automatically determined and the parachute is decelerated, and the speed of the return cabin is gradually reduced to about 7 meters per second.
However, if it hits the ground directly at such a speed, the absolute safety of the astronauts cannot be guaranteed.
To this end, the manned spacecraft development team designed a set of "combined punches", allowing the return cabin to make an emergency stop when it is one meter above the ground, and further slow down the landing speed through the return cabin to reverse the thrust of the engine’s reverse force. The damping system composed of the energy-absorbing shell at the bottom of the cabin, the damping material and the seat cushioning mechanism absorbs energy and ensures the safe landing of the astronauts.
(over)