Yang Liwei once heard a mysterious "knock on the door" in space. 13 years later, the experts finally found the answer.

On June/KOOC-0/65438+/KOOC-0/October/KOOC-0/6, 2003, after staying in space for 2/KOOC-0/hour for 23 minutes, Yang Liwei successfully returned to Earth in the manned spaceship Shenzhou 5.

This historic moment marks that China has become the third country to independently master manned space technology after the Soviet Union and the United States. And Yang Liwei has also become the "flying first person" in China.

On this day, countless viewers waited in front of the TV to welcome the space hero home with the staff on the ground. Everyone can't wait to hear what Yang Liwei saw and heard in space. But after Yang Liwei got out of the cabin, he said a word to the staff.

"I heard a knock at the door in space!"

From 2004 to 20 14, after 10 years' efforts, under the leadership of Liu Hong, a professor at Beihang University, China finally developed "Gong Yue No.1", the full name of which is: comprehensive experimental device for life support foundation of space base.

The role of "Yuegong-1" is to establish similar bases on other planets, where human beings can live, and the water, oxygen and food inside can be recycled to ensure the long-term survival of astronauts in space, even space immigrants. This provides a solid fortress for studying the situation in space and other planets.

The researchers conducted a 105-day closed experiment in "Gong Yue No.1" and observed that the cabin system was operating normally. But strangely, during the experiment, the researchers kept hearing a knock at the door.

At first, I thought it was the outside staff knocking at the door, but the staff present denied it. After that, the researchers chose to observe through monitoring, but confirmed that when there was a knock on the door inside the cabin, no one really knocked on the door outside the cabin.

This cast a shadow on the hearts of the experimenters of "Gong Yue No.1". Of course, they won't believe Machamp's derangement theory, but they are worried that there is something wrong with Gong Yue-1. Because building an ecological base for space exploration is a very complicated experiment. Any negligence may lead to the death of astronauts in space.

Professor Liu Hong began to do heavy troubleshooting with his team. In the process of troubleshooting, a staff member suddenly said a word, and others at the scene agreed.

"Do you think this kind of" bang "sound is not the first time? I seem to have heard it before? "

This knocking at the door is not accidental. In fact, it has happened many times in the space history of all countries in the world, but the reason has not been ascertained.

For the staff of "Gong Yue No.1", the most familiar thing is that when Yang Liwei returned to the ground in Shenzhou 5 in 2003, he told the staff on the ground that he heard a "bang" sound like wood knocking on an iron drum in space.

Compared with the situation of "Gong Yue No.1", Yang Liwei is obviously more terrible. Shenzhou 5 is the first manned spaceship in China. Yang Liwei is also the first astronaut in China to carry out manned space mission.

Unlike Shenzhou XIII, which has been popular recently, it can carry three astronauts, Zhai Zhigang, Wang Yaping and Ye Guangfu, to live in space 183 days.

At that time, the internal facilities of the "Shenzhou V" were not so perfect, and everyone was crossing the river by feeling the stones. Therefore, Yang Liwei is the only astronaut in the cabin, and the whole flight time is only 2 1 hour and 23 minutes.

Before that, no one knew what had happened in space. It can be said that both the staff on the ground and Yang Liwei are very nervous.

But I don't know if space deliberately played a trick on Yang Liwei. In this flight of 2 1 hour and 23 minutes, Yang Liwei has been troubled by irregular "knocking" sounds one after another. It seems that someone is knocking at the hatch.

However, this is absolutely impossible in space. Even if an alien creature knocks on the hatch outside, the sound will never reach Yang Liwei's ear.

Space is an absolute vacuum environment, and sound propagation needs to pass through a medium, such as air, so in space, sound cannot propagate at all.

So even if it is really an alien knocking at the door, Yang Liwei should not hear it. The question is, is it inside the cabin?

This is the first manned space flight. Yang Liwei dare not be careless. He checked everything in the engine room to see if there was anything wrong, but Yang Liwei found nothing after a round inspection.

He even looked out of the cabin by the porthole, trying to confirm whether there were really aliens. Of course not, there is only a vast universe outside.

Finally, Yang Liwei went to the front of the instrument dial to see if there was anything unusual. The instrument shows that all data of "Shenzhou 5" are normal.

Yang Liwei was sure that he heard the sound, but he couldn't find out where it came from, which was very scary in unmanned space.

However, the excellent quality accumulated by astronauts through hard training has stabilized Yang Liwei's mentality.

I believe that every astronaut in space is prepared for the worst before leaving. No one can guarantee the safety of the space project 100%, because this is a completely unknown world.

Therefore, after the initial panic, Yang Liwei ignored the knock at the door and continued to carry out his space mission.

Fortunately, although the knock on the door continued, the space shuttle was not affected. During the whole flight, all the data were stable. When it was time to fly back to Earth, the stone hanging in Yang Liwei's heart was finally put down.

After landing, Yang Liwei told the experts on the ground for the first time. When the experts heard this, they immediately organized a team to inspect Shenzhou 5's cabin.

Before departure, "Shenzhou 5" passed a strict inspection, but there is no guarantee that something went wrong during the flight.

After inspection by a professional team, it can be ensured that "Shenzhou V" is still no problem. At this time, the experts turned their thinking direction to the other side, that is, the astronauts' own problems. Space travel is a very psychological t..

Humans are gregarious animals and cannot live without groups. In the space far away from the earth where human beings live, there is no life or sound. Astronauts are likely to have psychological problems and have auditory hallucinations.

To this end, they tested Yang Liwei and tried to restore the sound he heard, but Yang Liwei said no, which he described as the "bang" sound of wood hitting the iron drum.

After some fruitless research, both experts and Yang Liwei intend to put this matter on hold for the time being. Because the whole flight went smoothly, the spacecraft did not have any problems. This little knock on the door is harmless.

After Yang Liwei, China successively launched manned spacecraft Shenzhou VI and Shenzhou VII, but every returning astronaut said that he heard a knock at the door in space.

This also confirms that Yang Liwei is not hearing voices. This sound has become a symbol in flight, just like the sound from space. However, under the appeasement of Yang Liwei's predecessors, the astronauts of Shenzhou VI and Shenzhou VII did not panic at this sound and successfully completed their tasks, making great contributions to China's manned spaceflight project.

The experiences of Yang Liwei, "Shenzhou VII" and "Shenzhou VIII" made the staff of "Gong Yue I" more certain that the problems they encountered should be the same as those of Yang Liwei, or even the reasons may be exactly the same.

If we can find out the reason, it can also provide reference for astronauts' space work in the future. Moreover, "Yuegong-1" will be used for deep space exploration in the future, and the entire survival of astronauts depends on this system, if it suddenly breaks down in space. The astronaut's life safety cannot be guaranteed, and he may not return to Earth immediately.

Based on this, the staff of "Gong Yue No.1" not only tested the system, but also studied the source of sound more carefully.

They checked the whole cabin because the sound was irregular. Experts speculate that it will only make sound under some special circumstances, so they pay attention to the variables in the engine room again.

Finally, after unremitting observation and research, they found that when the engine room temperature changes, there will be a "knock on the door." However, the temperature change of the cabin will affect the material of the inner wall of the cabin. When the temperature changes, the material will be slightly deformed, and sound will be made during the deformation.

It turns out that in the process of space flight, the outside temperature is different when the aircraft passes through different areas. At the same time, the temperature in the engine room can also be adjusted in real time according to the outside temperature. The change of temperature will drive the change of cabin pressure. Similar to the feeling of "expansion with heat and contraction with cold".

Shenzhou 5's return capsule used a low-density heat-proof material, which was selected by scientists for Shenzhou 5 through numerous experiments, and it is one of many key technologies. With this technology, Shenzhou 5 can guarantee to cope with the harsh temperature environment in space.

Even if it has reached 3000 degrees outside, Yang Liwei in the cabin can still be in a 20-degree environment. Even so, in the face of the temperature change in outer space, the material of the inner wall of the cabin will inevitably be slightly deformed, but it is still within the safety limit and will not have any impact on the personal safety of astronauts.

This result is also a reassurance for later astronauts. Not only for our country, but also for foreign astronauts.

Because the sound heard in outer space is not only encountered by astronauts in our country. America met before us. As early as 53 years ago, they had heard this kind of "space music" for the first time.

And more than one person. If the astronauts of Shenzhou VI and Shenzhou VII had Yang Liwei's guidance, they wouldn't panic. Then the only person in the world who can understand Yang Liwei's feelings is probably the Apollo 10 pilot who also entered space earlier.

But they chose to hide it for more than forty years.

What Yang Liwei heard in space was the "pop" sound caused by the deformation of the cabin wall material, while the pilots of Apollo 10 heard more complicated sounds.

This event can be traced back to 1969 May 18. American astronauts thomas stafford, john young and eugene cernan once flew into space in Apollo 10 and completed the mission around the moon.

It was the successful completion of this mission that laid the foundation for Apollo 1 1 to complete the mission to the moon. The famous "one small step for man, one giant leap for mankind" comes from this mission to the moon.

At that time, the aircraft was divided into two parts: the command module and the landing module. The mission around the moon is to separate the two modules and then try to descend to a place near the surface of the moon.

When the two cabins were separated, three astronauts in the cabin suddenly heard a voice. The sound lasted for nearly an hour. The astronauts in the cabin recorded this sound and planned to bring it back to Earth before doing research.

At that time, the three astronauts in the cabin were in the same mood as Yang Liwei, and they all felt terrible and frightened when they heard this sound in the open space. But they didn't radio this thing to the ground in the plane, but recorded the sound.

After returning to the ground, the three astronauts sent this recording to NASA for the next mission to the moon and not to affect the astronauts' mood. They all chose silence.

Facts have proved that their choice is correct. The mission of "Apollo 1 1" has not been affected in any way, and the United States has become the first country to land on the moon in history.

It was not until 2008, more than 40 years later, that these mysterious recordings were made public. There are many speculations about the reasons for this sound, such as atmospheric and magnetic interference, which NASA itself interprets as radio interference in the cabin.

No matter what kind of explanation, it seems untenable. Even the authenticity of this recording is in doubt at present. After all, we have been apart for more than 40 years. Therefore, the mystery of the sound of "Apollo 1 1" has not been determined yet, and astronauts need to continue to explore in space in the later period.

Space exploration has always been a major project in our country. Countless people have walked wave after wave for this space dream, and every astronaut who flies into space has also walked with some kind of consciousness.

The staff on the ground can only do their best to ensure the safety of astronauts in space. However, there may be various abnormal situations in space, and we can only improvise by the calmness of astronauts.

The pace of space exploration will not stop, and China will always be ahead.