Overview
Why do spacecraft fly through the atmosphere and return to Earth at high speed?
For a long time, human exploration of the universe has never stopped. The vast universe, the vast starry sky, and the mysterious universe seem to have a special attraction to humans in nature. In ancient times, humans tried to use astrology to unlock the mysteries of the universe. Now, with the rapid development of technology, humans have developed spacecraft that can truly step out of the earth and come to the universe to explore the secrets.
And about spaceships, do you really know it?
On April 21, 1961, when the Soviet Union successfully launched "Oriental 1" from Earth to outer space, the spacecraft era officially began. Then, more spacecraft flew to space to explore the mysteries of the universe.
spacecraft carries the important task of exploring outer space, but when it completes the mission successfully and returns to Earth, it always makes a strange move. The spacecraft needs to increase its speed when flying over the atmosphere, causing the body to burn. Why is this?
Why doesn’t the spacecraft burn when entering space?
also has acceleration. Why does the spacecraft not cause combustion when entering space, but burn when returning to Earth? To uncover this secret, we must first understand the principles of spacecraft entering space and operating in space.
is affected by the powerful gravity of the earth, and it is extremely difficult for the spacecraft to leave the earth. If you want to escape the constraints of gravity, must reach the first cosmic speed of , which is 7.9km/s.
. If you want to achieve such a speed, the spacecraft itself is far from reaching it. To solve this problem, people generally use rockets as power tools to help the spacecraft take off.
also accelerates the speed of entering space, Why does the spacecraft not burn when it leaves the earth, but returns to the earth? There are three reasons for this.
First, affected by the gravity of the earth, when the spacecraft first took off, the speed of was actually not as fast as people imagined. The powerful drag of the gravity of makes the spacecraft enter space only to get rid of the gravity of , and its speed is only a little faster than the ordinary fighter , so the friction with the atmosphere is not so strong.
second, Generally, there are high-temperature resistant "titanium" substances on the shell of a rocket. can greatly protect the rocket shell to avoid damage to the rocket shell under high temperature conditions. In addition, the heads of the rocket are equipped with an fairing , which can effectively isolate heat and protect the rocket from high temperature damage.
33. Rockets usually take off in a vertical form , so they can also accelerate through the atmosphere to a certain extent, and the contact time with the atmosphere is not much.
With the above three points, the spacecraft will not easily cause fire or burn when entering space.
Return to the mysterious black barrier area that returns to the earth?
As the saying goes, "It is easy to go up the mountain and difficult to go down the mountain." This sentence also applies to spacecraft. When the spacecraft completes the mission and wants to return to Earth, the external conditions it faces are very different from those when it takes off. Among them, if you want to successfully return to the earth, has to go through the most important and dangerous stage - the black barrier area.
What is the black barrier area?
In fact, when the spacecraft returns to the atmosphere, shock waves are generated around the spacecraft, This will make the temperature of gas molecules around the spacecraft very high, and such high temperatures are not easy to dissipate. will form a high temperature zone with a temperature of up to thousands of degrees Celsius.
It is precisely because of the increase in temperature that causes gas molecules near the spacecraft cabin to form a plasma layer by decomposition and ionization. The plasma layer such as is like a cover, absorbing electromagnetic waves , turning the spacecraft cabin into a completely closed body, causing the spacecraft to completely lose contact with the ground, which is called the "black barrier area".
Black barrier zone is a very terrifying period for many astronauts. During this period, will completely lose contact with the ground and can only rely on the astronauts' self-operation. If you are not careful, you will die of the universe.
such as my country's "business trip trio" Zhai Zhigang , Ye Guangfu , Wang Yaping encountered a "black obstacle for six minutes" when he returned this year.
How to return safely in spacecraft?
spacecraft operates in space at a speed of 7.7 km/s, , so it is very difficult to reduce such a high speed in a short period of time. When a spacecraft returns to Earth, the brake rocket will usually start, slow down the spacecraft, so that the spacecraft will break away from its original orbit and enter an orbit intersecting with the Earth.
When the spacecraft enters orbit, also needs to adjust the fuselage position, jump into the atmosphere at a suitable angle, pass through the terrible black barrier area, and reach the second cosmic speed 11.2 km/sec to return to the earth.
And in these processes, the spacecraft will also cause the shell to rub violently and burn due to the high temperature. The reason why does this is because it is currently the cheapest and least subsequent damage in this way.
Someone has proposed to deal with combustion losses by using reverse acceleration and increasing the material of parachute , but experiments have proved that reverse acceleration requires additional combustion more energy, while improving the quality of parachutes requires the development of a parachute material that can withstand high temperatures.
these methods are still unavailable, and it is still difficult for humans to break through the difficulties of "black barrier zones" because the upper gas is uncontrollable.
The spacecraft journey is still continuing
Although there are so many difficulties ahead, human beings have not given up on exploring in the universe. The aerospace industry itself is a great and dangerous industry. When we are intoxicated by the splendor of the starry sky, there are also many dangerous elements lurking in the darkness, and these dangers need to be continuously explored by humans to overcome.
From the moment the human space dream was born, it was destined to make many sacrifices for this starry sky.
Today's spacecraft are also gradually improving their performance with the continuous development of technology to ensure the safety of astronauts. I believe that in the near future, humans can go deeper into the universe through spacecraft, and the spacecraft journey continues.
