How can we build an elevator to go to space and fix it to the rotating earth? There is no need to fix it

Space elevator, a concept that sounds very sci-fi, is very likely to become a reality in our lifetime. Some Japanese scientists even predicted that humans will build the first real space elevator as early as 2050. Is this possible? It is possible. If you ask me why I say this, it is because it came from the mouth of Tsiolkovsky.

Born in Russia in 1857, Tsiolkovsky was a mathematics and physics teacher. He also had another title recognized by the scientific community, that is, "the father of astronautics." If you know nothing about Tsiolkovsky, then you will be confused by this title. How can a Russian living in the 19th century be called the father of astronautics? You should know that it was not until December 17, 1903 that the Wright brothers invented the airplane and completed the first test flight. In other words, Tsiolkovsky had never even seen an airplane.

Not only had Tsiolkovsky never seen an airplane, he was also born deaf and even taught himself mathematics and physics. However, he dared to imagine and believed that humans would one day be able to leave the earth and travel into the universe.

Since it is believed that humans can leave the earth, they must come up with a method, otherwise it will become nonsense. So Tsiolkovsky proposed the idea of ​​a jet rocket, and then proposed liquid rocket fuel and multi-stage rocket solutions. Now we all know that Tsiolkovsky's advanced ideas have all become reality, so Tsiolkovsky deservedly won the title of "Father of Astronautics". In addition to rockets, Tsiolkovsky also conceived another way to go to space, that is, the space elevator.

Compared with rockets, the idea of ​​a space elevator is much more mysterious. The earth is not a static sphere, it is rotating all the time. At the equator, the linear speed of the earth's rotation can reach 1,670 kilometers per hour. How can a thin and long elevator stand on such a high-speed rotating sphere? This sounds impossible, but it is actually possible.

Objects with mass have gravity, and the greater the mass, the greater the gravity. The Earth is a sphere with a mass of 5.965x10∧24kg, so the gravity is quite strong. Even if you reach the first cosmic speed and enter the low-Earth orbit, you will still be affected by the Earth's gravity. In addition to being affected by gravity, objects orbiting in the Earth's orbit are also affected by a virtual force in the opposite direction of gravity, that is, inertial centrifugal force.

The gravitational force on an object is inversely proportional to the square of the distance, that is, the farther away from the earth, the smaller the gravitational force it experiences. However, the inertial centrifugal force on an object is directly proportional to the distance. The farther the distance, the greater the inertial centrifugal force. Therefore, at a certain height above the earth's surface, the magnitude of the gravitational force and the inertial centrifugal force tend to be consistent, achieving a balance. This position is called the "geosynchronous orbit" by us.

Objects in geosynchronous orbit move synchronously with the rotation of the Earth, so from the Earth's perspective, objects in this orbit appear to be stationary, so this orbit can be used to place the terminal of the space elevator. Now that the terminal is in place, the next question is how to connect the starting point on the ground with the terminal in space.

The geosynchronous orbit is located 36,000 kilometers above the earth's surface, but when we build an elevator we cannot only build a length of 36,000 kilometers.

Because the gravity of the earth on the elevator body below the geosynchronous orbit is greater than the inertial centrifugal force, it is inconsistent with the rotation speed of the earth and cannot stand. To solve this problem, the elevator needs to be built longer, that is, the total height of the elevator body must be much higher than the height of the geosynchronous orbit. In this way, the inertial centrifugal force on the elevator body above the geosynchronous orbit is greater than the gravity of the earth, while the gravity of the earth on the elevator body below the geosynchronous orbit is greater than the inertial centrifugal force, so the two sections of the body are pulling each other. If the forces on the two sections are equal, then balance can be achieved, and the entire elevator does not need any support and can stand above the earth under the balanced action of gravity and inertial centrifugal force.

From a theoretical point of view, the concept of a space elevator is completely in line with the facts. Even with the current level of human technology, it can basically meet the construction conditions. If there is anything missing, it is the construction materials.

The construction of a space elevator relies on the balance between the gravity and inertial centrifugal force of the main part of the elevator, and this balance is achieved by "pulling", so the materials needed to build a space elevator must have sufficient strength. Currently, the only material known to meet the requirements of building a space elevator is carbon nanotubes, but we cannot make this material very long. The longest carbon nanotube material in the world is only half a meter, which was made by researchers from Tsinghua University. Therefore, it will take some time to build a space elevator of tens of thousands of kilometers.

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