How did humans return to China after landing on the moon? Is there a rocket launching base on the moon?

In the last century, America sent astronauts into space and returned safely. But today, some people are still curious. If you want to send an astronaut to the moon, you must use a rocket to boost it. But there is no rocket launching base on the moon. How will astronauts return to earth?

The escape velocity of the earth Newton is a world-famous scientist. When he was alive, he once put forward a thought experiment. He thought that if there was an ideal cannon, he would erect it on a high mountain and launch it. It stands to reason that the cannon will be a parabola, flying forward for a certain distance and then falling to the ground.

However, if we increase the initial velocity of the shell and make it fast enough, although the shell will fall like a parabola, the earth is not flat, but a curved sphere. This leads to how many meters the shell falls, and how many meters the surface of the earth also falls, so the shell will never fall on the earth, and this speed is the first cosmic speed.

If the initial velocity of the shell is faster, then the shell will directly rush out of the limit of the earth's gravity and rush to the universe. This speed is also called the second cosmic speed.

The second cosmic speed, also known as escape speed, refers to the lowest speed at which objects on the earth want to leave the earth's surface. The second cosmic velocity of each celestial body is different. On earth, the speed of the second universe is11.2km/s. ..

Scientists need to reach 1 1.2 km/s to launch satellites or spacecraft to get rid of the gravity of the earth. At present, no aircraft can reach this speed directly, so it can only be boosted by rockets, so we will see that when launching satellites, they will be tied to rockets and launched together.

In the 1970s, Apollo 1 1 was also launched in this way. Its rocket is Saturn 5 SA-506. With the help of the rocket, Apollo 1 1 entered the lunar orbit.

How did Apollo 1 1 leave the moon? The first thing to know is that not all Apollo spacecraft have entered the surface of the moon. In fact, Apollo spacecraft includes several parts, namely, the descending part of the lunar module, the ascending part of the lunar module, the command module and the service module.

When Apollo 1 1 entered the lunar surface, what was the call sign? Eagle? What are the call signs of the ascending and descending sections of the lunar module? Colombia? In the command module, only astronaut Collins stayed on Columbia, and the other two astronauts entered the lunar module.

Collins, the astronaut who stayed on Columbia, flew around the moon in the command module, waiting for their return. If they can't return, he can only return to earth alone.

The two astronauts left in the lunar module will enter the surface of the moon and carry out a series of work. After completing these tasks, they will enter the ascending section of the lunar module. At this time, the ascending section will inject violent gas downward, so that the ascending section will have a certain initial speed to reunite with the astronauts on Columbia.

In other words, astronauts want to leave the moon without the help of rockets. Why?

In fact, it is because the escape speed of the moon is very small, and the escape speed is related to the mass of celestial bodies. The greater the mass of celestial bodies, the greater the escape velocity; The smaller the mass of the celestial body, the smaller the escape velocity. The mass of the moon is smaller than that of the earth, and the gravity of the earth is dominant in the earth-moon system, so the escape speed of the moon is not high, only 2.4 km/s.

Because the escape speed of the moon is not high, the aircraft can reach the escape speed even without rocket boost, so astronauts can return to earth from the moon again after landing on the moon.

But the plan to land on Mars is not so lucky. 100 warriors who will enter Mars in the future have been recruited abroad on the condition that they will never return to Earth.

This is because Mars is far away from the earth, and the escape speed of Mars is 5.02 km/s. Without rocket boost, the aircraft cannot reach this speed. There is no rocket base built by human beings on the surface of Mars, so manned landing on Mars is essentially a one-way trip with no return.

To sum up, at present, our technology can send astronauts into space and return to earth. The reason why there is no manned moon landing plan at present is actually because manned moon landing is risky. Moreover, what humans can do, machines can also do, machines can sleep on the moon, and they can continuously provide information about humans on the moon.

Secondly, because the development of manned space flight is no longer a sign of the strength of a big country, we don't need to send astronauts to the surface of the moon.