2020-07-16

There are no rockets and launch towers on the moon. How do Americans return? Scientist:hitchhiking

By yqqlm yqqlm

Flying out of the earth and ascending to other planets is not terrific, but you can come back to be a”master”! The American landing on the moon is already a thing of the last century. With the continuous improvement of scientific cognition and technological level, there are more and more voices of doubt. After the spacecraft landed, how to return home was a big technical problem, especially in the last century.

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Know that Apollo is Titan The No. 1 carrier rocket has brought it to the sky. The thrust of the rocket is still the second in the world , and there is no such powerful rocket and launch tower on the moon.

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The key to the problem of return flight is gravity, because of the background of the incident It’s Earth-Moon System To give an inappropriate example, From the Earth to the Moon looks like Climbing the hill, and returning from the moon to the earth is a downhill path. The return plan is limited to the moon, neither Mars nor Venus. Next, let’s get rid of the doubts about the first human landing on the moon.

Moon landing

From the earth to the moon is divided into:

  • The rocket accelerates to overcome the gravity of the earth Lifted off into Earth orbit
  • The rocket once again accelerated away from Earth orbit and entered the earth-moon transfer orbit, flying to the moon 380,000 kilometers away
  • Cut into the moon orbit with a certain speed, Overcome the gravity of the moon, and orbit the moon,
  • Slow down slowly, let the gravity of the moon slightly prevail, and use the gravity to slowly fall around the moon.
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There are no flaws in the login process, Everything is logical, but there are some details in the process, which laid the groundwork for the return of the Apollo.

Preparation for return

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In the process of flying out of the earth, as the fuel is exhausted, the Titans are separated from each other. When they enter the earth-moon orbit, the tip of the rocket is the sharp point. The part is the command cabin and the middle service cabin, which is separated from the rocket and has a 180-degree rotation.

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Picture:the command cabin that has been turned over, prepared and registered Lunar module”kissing”

After adjusting the”head” and”feet” one by one, they came back to dock with the lunar module in the middle. Look at the big fumarole on the”feet” of the service module , I want to know with my feet that the service cabin carries fuel. Immediately after, the command module and the service module took the lunar module and the last section propulsion of Titan to enter the earth-moon orbit.

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When the Apollo landed on the moon, humans walked down”A big step”, inserted a small flag, picked up the stone, and was ready to go back. The sharp-eyed kid may have found out, where did the”pointy” command cabin and service cabin just transferred? There are also three astronauts sent to the moon. Why are there only two people disembarking?

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In fact, there is no one on board, because another astronaut has nowhere to go Not on the moon, while in orbit around the moon in a combined state, Armstrong and Aldrin hid in the lunar module, Then it disengaged from the command module and slowed down to land on the moon. And Michael Collins continued to stay in the command cabin, circle around the moon, the command cabin is the return car, he is waiting for the next task-take everyone home.

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Rocket The escape speed of

The key factor for Apollo’s takeoff is the gravity of the moon. On the playground, throw a ball that can be thrown 30 meters away. If you are on Mount Everest, you can throw farther, because there is a slope between the mountain and the ground. The earth is not flat, but round. If the ball has enough initial velocity when leaving the hand, so that the ball has left the earth and has not landed, then the following will happen:

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Spherical ring-to-earth movement, to reach the initial speed of the ring-to-earth movement, called the first universe velocity 7.9 km/s. If the force is greater, the gravity of the earth can’t make it change its mind, it will happen the following:

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This situation is called escape, and the escape speed of the earth is also called the second cosmic speed, 11.2km/s. The escape velocity is only related to the mass of the celestial body and the radius, and the mass and the radius determine the gravitation of the celestial body. Therefore, scientists often use the escape velocity to describe the gravitational strength of the celestial body. For example, black holes, the high-speed light of the universe cannot escape, so black holes Very attractive.

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From The moon returns to the sea

The gravity of the moon is very small. Its escape speed is 2.4km/s. Armstrong wore a heavy spacesuit and walked carefully and jumped. If it jumps hard, it is estimated that it can Seconds on the pole vault record. This means that there is no need for a powerful propeller such as Titan on the moon, only need to be equipped with a”mini rocket” and”mini launch pad.”

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The Apollo lunar module is divided into two parts. Some of them are descending stages. Carrying a small amount of fuel can steadily land the spacecraft on the surface of the moon. When the spaceship is about to leave, it unlocks with the upper part and transforms into a launch pad. The upper part is upgraded, and it also carries a small amount of fuel and engine. This mini structure is enough to support it to fly away from the surface of the moon against gravity. When the lunar module is upgraded to return to the lunar orbit, and docked with the command module, the return home is passed to the”large capacity jet” (service module).

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In fact, in the whole process, except people and stones The entire part of the moon landing was abandoned on the moon. The descending stage as a launch pad stays on the surface of the moon forever. The upper part is that after the command module is docked, the two astronauts in the lunar module enter the command module with”stones”, and then the lunar module in the ascending segment is separated from the command module, and is abandoned on the lunar orbit. Slowing down slowly will eventually fall into the lunar surface. So why do you have to split and combine a good moon landing?

Choose a variety of options

Several options for landing on the moon were envisioned at the time:

  • Take off directly

The rocket takes the spaceship to take off to the moon to log in. After taking the stone, the rocket takes off again and returns to the earth.

  • Meet in Earth orbit

The rocket can be smaller, but two ships are used to send the lunar module and the command module to Earth orbit for docking, Fly to the moon again, and then return as a whole.

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Picture:a picture of a direct take-off or a set of earth orbits

  • The lunar surface meets

It also uses two ships, one unmanned, with thrusters to log in to the moon, and then the manned lunar module reaches the moon , The astronaut took the stone and entered the spacecraft that had arrived first, then propelled up and returned to the earth.

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Figure:The whole process of the lunar orbital meeting plan

  • Lunar orbital rendezvous

This plan is the one used by the Apollo to land on the moon. A large rocket carries two spacecraft, and the larger one is loaded back to Earth. Fuel and necessities, as well as the heat insulation panels required to assemble into the earth’s atmosphere, are not part of the moon, only the moon. The other, lightly packed, has a smaller mass and only carries people, and has a small amount of fuel for landing on the moon and returning to the lunar orbit from the surface of the moon. After exhausting all the fuel in the service cabin, only a small conical command cabin was left in the atmosphere and fell into the sea.

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Energy

The last option was chosen because of energy considerations. The energy required by the spacecraft is mainly to overcome gravitational takeoff and orbit change. There is no need to consider energy when flying to the moon, because we have a perfect launch pad and a powerful rocket.

And when the moon rises, it is stretched. Although the gravity of the moon is small, it also needs to reach a certain initial speed to take off and rise to the lunar orbit. The greater the mass, the greater the energy required for take-off acceleration, so the mass of the moon landing part needs to be compressed to the smallest possible.

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The Apollo 11 badge is an eagle landing on the moon. From the side, this is a very figurative metaphor. The lunar module is like an eagle, it looks like a big body. It is actually not heavy, the main quality is concentrated under the feathers. The eagle claw represents the descending section of the lunar module. When landing, the two claws can be separated to lock the ground firmly.
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Wings represent takeoff, after completing the mission, the eagle claws change In order to fix the launcher on the ground and stay on the moon, the fuel and thrusters carried in the ascending section are like wings of an eagle taking off with them. In the end the eagle completed the mission and stayed on the moon. The larger spacecraft (service number) has sufficient fuel and can make several orbit changes, plus the earth’s gravitational traction as the dominant earth-moon system, and finally the stone and the astronaut go home.

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Mars Can’t come back

The whole process of landing on the moon is very smooth and perfect, and there is nothing to question. Now they have been aiming at Mars for a long time. The one-way journey of Mars takes at least 39 days, and the moon only takes 8 days to and fro, and the distance indicates fuel. Mars is much larger than the moon, and the escape speed is about 5km/s. Sending a probe to Mars, the landing vehicle is not a problem for humans.

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If you want to take off from Mars and carry a lot of fuel and It is difficult to return the living supplies to the earth. The mini launcher and engine cannot make the behemoth reach the speed of escape. We need to have a launch base on Mars, and we can use and extract the fuel on Mars to return home, so Americans have not yet sent people to Mars.

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Apo Luo’s plan ends

After Apollo 11, Armstrong hit his head, Apollo planned to successfully land on the moon many times, and inserted many flags around the moon, and finally also tired, the stone should be picked up I picked it up, there is nothing new, the key is super expensive. So after Apollo 17, the Americans terminated the Apollo program. A big step can be taken, and then back, this is the master’s operation!

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