Most of the extraterrestrial space exploration videos that people watch are basically silent, and some BGM is added later.

This has to do with the fact that the authorities don't play the original sound, and it also has to do with the fact that there is really no sound to hear in space.

Sound is a wave that travels through a medium, but some waves are large and some waves are small.

The denser the medium and the closer the distance between molecules, the greater the ability to propagate sound, because the essence of sound is transmitted by the collision of molecules in the medium.

Space is not an absolute vacuum, but its medium density is very small, and the intermolecular distance is super large, and it can't touch one in half a day, so the ability to transmit sound is very, very, very weak.

In the process of operation of space exploration equipment, there is naturally sound, and the collision of various pipelines and components will produce sound, and ordinary people are not interested in this sense of sound, not to mention, the general sound receiving device may not be installed on the space exploration equipment.

Because the load of each rocket launch is "calculated", it is too expensive, and it is a waste of load to install such "useless" equipment, isn't it fragrant to install other scientific research equipment?

For example, electromagnetic signal detection equipment.

This thing can pick up electromagnetic waves from the planet, and scientists can convert those electromagnetic waves into sounds that can be heard by the human ear, and then people can listen to the sounds coming from space.

Don't you say, the sounds of the planets of the solar system sound ...... It's quite chic.

The "hum" of the sun.

The "whistling" of Mercury.

The "chime" of Venus.

The "wind" of the earth.

Martian......

Horror, horror, wailing, majestic, singing, deathknell, etc., all kinds of sound effects will even make people feel natural fear, hair stands on end, and finally deepen one's deep-space phobia.

Fortunately, those sounds are inaudible to the human ear, and require the conversion of various devices, and human beings do not suffer from that kind of sin every day.

Of course, this thing is "artificially translated", and if you use different ways to "translate", you will get a completely different sound, so just listen to it.

On a planet with an atmosphere, the direction of detection is different.

Because they have air on them, people can hear sounds in the same way as the Earth.

As Earth's two neighbors, Venus and Mars, humans have studied them "most thoroughly", including the sounds in their atmospheres.

On Venus, everything will be muffled.

If the soprano on Earth is on Venus, it will become deeper than the bass, so the beautiful songs on Earth will probably not be wonderful on Venus, just like the record player is about to run out.

If the tiger on Earth is on Venus, the tiger's roar will be thicker and deeper, but it will feel like a rough voice made by an unusual little animal, not only low, but also faint.

It's probably a tiger that doesn't make a threat, or a kitty cat that looks like a tiger and has a pink bow.

But even the most muffled sound, it can travel very fast and very far away on Venus.

Why is this happening?

As mentioned earlier, the propagation of sound is related to the type, density, and temperature of the gas.

In a gas with larger molecules, higher density, and lower temperature, the faster the sound travels, but the lower the vibrational frequency of the sound, that is, the lower the tone.

It is easy to understand that dense matter travels faster than a solid such as steel on earth than a liquid such as water, and water travels faster than air.

People and people cannot be generalized, and neither can planets and planets.

Venus's atmosphere is as dense as liquid, 100 times denser than Earth's, and much more pressurized than Earth's.

It takes more energy to stir up fluctuations in a dense atmosphere in such an environment.

So if it's the same sound vibration, when you get to Venus, the Venus gas it provokes vibrates less amplitude, so the tone becomes coarser and the sound becomes weaker.

The sound on Mars will be the opposite of that on Venus, the sound will become sharper on Mars, but the speed of sound travel will be much slower, and the distance will be much shorter.

That's because the sound propagation on the surface of the earth is equivalent to the atmosphere at an altitude of 30,000 meters above the earth, and the air is thin.

More than a decade ago, Merriken's space agency launched the Phoenix rover to detect life beneath the soil or ice caps of the Martian poles.

On that Mars landing, scientists added microphones by the way.

The Phoenix landing was lucky, and the whole process was captured by Europa's Mars Express orbiter.

Through the microphone on the Phoenix, scientists can hear the sound of the Phoenix landing.

As it descended with the parachute, it heard the sound of fine raindrops, and then the sound of raindrops mixed with whistles, which became more and more shrill.

When the Phoenix free-fell from the parachute, the whistle became unusually harsh, and then the landing recoil engine turned on, and a robot-like sound could be heard.

Scientists interpret the increasingly high-pitched whistle sound as follows: It should be the Doppler effect when Europa's Mars Express flies over Phoenix.

It's like when a train comes from afar, we feel the horn getting louder and louder, and as the train passes, the whistle becomes deeper and lower.

The sound of Phoenix's passage through the Martian air is indeed much sharper than that on Earth, but it is getting sharper and sharper, and it is so shrill that it is the result of the Doppler effect.

As for the sound of fine raindrops, scientists initially speculated that it was caused by the impact of dust or ions on the rover over Mars.

Today, the Trailblazer, which uses "ton" as the basic mass unit, is equipped with a more sophisticated sound recording device, which can hear various sounds more clearly.

The sound of the "Sky Blazer" unmanned exploration helicopter taking off is very loud, but it is transmitted to the sound recording device through the thin air, and then converted into a signal to the earth, and then converted into a sound, and what hundreds of millions of humans hear is a sharp "buzz", and the sound is not loud.

Fortunately, when the landing equipment first entered the atmosphere, they also heard a subtle "raindrop" sound, so the volume was turned up, and now the sound can be heard.

However, as the helicopter flew higher and higher, after only a few dozen meters of flight, people could not hear the sound.

Where the air is thin, the sound propagation distance is so urinary.

And the rest is a helicopter for a few hours to travel.

Although Tang Chao knew who the four aliens were, the other earthlings didn't know, so he could only pretend not to know, and developed a complete set of contact methods for this purpose.

According to the single flight time of the helicopter, it is possible to fly directly from the landing site to the location of the alien, but no one allows him to play like that, and he must land and repair when he is close to the location of the alien, and then fly over after the flight power is charged.

If it flies straight over, the helicopter will definitely enter a "stiff" time of up to 30 minutes, in case there is an interstellar diplomatic conflict, it will not be able to run if it wants to.

Therefore, it is necessary to ensure that the power of the helicopter to support the flight is relatively sufficient, and if there is a problem, it will fly away immediately.

The alien spacecraft crashed, and after long-term satellite surveillance, it was found that they had no extra flight equipment, and there was a high probability that they could not cause damage to the helicopter, and they could not catch up with the flight speed of the helicopter, and the helicopter could run away, and then think about it in the long run.

This is a rare opportunity to make contact with aliens, even if it is not led by itself, and no country wants to waste this opportunity at will, especially those countries that do not have space capabilities.

Yes, Tang Chao was connected to the United Nations General Assembly this time, and his avatar also appeared at the scene of the United Nations General Assembly, and the largest screen at the scene showed the live broadcast screen this time.

If there is an accident in this contact, the next contact will not be the business of most countries.

After all, other countries will not broadcast live globally like Navigator, although they have signed an information sharing agreement, but there is no live broadcast, how credible can the shared information be?

It's an alien encounter.