How does the manned spacecraft go home? A manned spaceship

Many media reported that the Soviet manned spacecraft 1 crashed at a speed of more than 100 meters per second before 1967 returned to land, and astronaut komarov was killed. How did the manned spacecraft return to Earth and land safely?

After the manned spacecraft completes its scheduled mission, the return capsule carrying astronauts will return to Earth. The spacecraft flies around the earth at a cosmic speed of about 8 kilometers per second in space hundreds of kilometers away from the earth, and the time for the spacecraft to return to the earth is very short. Under such conditions, how can a manned spacecraft return to Earth and land safely?

When the spacecraft returns to Earth, it will go through four stages: deorbiting, free descent, re-entry and landing. Only after each stage of the mission is completed accurately and smoothly can the spacecraft successfully return to Earth and land safely at the scheduled location.

Off-track part

The stage when the spacecraft enters the return orbit from the original flight orbit is called the deorbiting section. When the ground monitoring station sends a return command to the spacecraft, the spacecraft's return program is started. First, the spacecraft control system adjusts the spacecraft's flight attitude to complete the yaw action, and then the orbital module is separated from the return module and the propulsion module. The spacecraft should adjust its attitude again, make its tail face the flight direction, and ignite the engine brake. Because the spacecraft was subjected to the force opposite to the flight direction, its speed decreased, so the spacecraft broke away from the original orbit and entered the return orbit. Once the spacecraft return program is started, it can't be corrected halfway, nor can it be started all over again. Therefore, it needs to be controlled very accurately. For example, if the engine braking and ignition time are different by 1 s, the landing position of the return capsule will be different by 9 kilometers.

Free descent section

From leaving the original orbit to entering the atmosphere, the spacecraft is in a high vacuum environment, and there is no air resistance. The spacecraft is in a state of free descent under the action of the gravity of the earth, so this stage is called free descent or transition. At this stage, the propulsion module should be separated from the return module, and the attitude of the return module before entering the atmosphere should be adjusted again to establish the correct reentry attitude angle (the angle between the spacecraft speed direction and the local horizontal plane). This angle should be accurately controlled within a certain range. If the angle is too small, the spacecraft will pass through the edge of the atmosphere and cannot return. If the angle is too large and the spacecraft returns too fast, the spacecraft will burn in the atmosphere like a meteor.

Reentry section

When the spacecraft takes off, it passes through the atmosphere, and when it returns, it must re-enter the atmosphere, so this stage is called re-entry stage. After the return capsule enters the dense atmosphere, it has to undergo aerodynamic heating and reentry overload, which is the most severe and complicated stage in the return process. With the decrease of altitude, the air density is increasing, and the resistance of the return capsule is also increasing. Due to the intense friction between the return cabin and the air, the temperature of its head is as high as several thousand degrees, and the return cabin is surrounded by flames. Whether the spacecraft can withstand high temperature is the key to successful return, so special heat protection measures should be taken for the return capsule.

Landing part

The stage from parachute opening to landing is the landing stage. With the decrease of altitude and speed, the aerodynamic drag of the return capsule and the gravity of the earth gradually tend to balance. At this time, the return capsule descends at an average speed of about 200 meters per second. If the spacecraft rushes to the ground at this speed, the consequences will be unimaginable, so it is necessary to slow down the return capsule. When it is about 10 km from the ground, the deceleration landing system should be started accurately and reliably, the umbrella cover should be ejected, and the guide umbrella, deceleration umbrella and main umbrella should be pulled out in turn, so that the return capsule can slowly descend at a speed of 6-8 meters per second, and the heat-proof outsole should be thrown away. When it is about one meter from the ground, the buffer engine should be ignited to make the return cabin soft landing at a speed not exceeding 3.5 meters per second. After the spacecraft landed, the ground recycling team quickly rushed to the scene to carry out recycling according to the radio signal sent by the return capsule. ★