What novel and wonderful manned lunar landing plans and tools were designed in the Apollo project?

The entire Apollo manned lunar landing project lasted about 11 years, and the sixth lunar landing was successfully completed in December 1972, costing $25.5 billion (equivalent to about $200 billion today). At the peak of the project, 20,000 companies, more than 200 universities and more than 80 scientific research institutions participated in the project, with a total of about 400,000 people, which concentrated on the level of modern science and technology and promoted the rapid development of aerospace technology.

How was the lunar landing plan for the Apollo project determined?

During the implementation of the Apollo manned moon landing project, it took a long time to determine the moon landing plan. Until May 25, 1961, when President Kennedy officially announced that the United States would implement the Apollo moon landing plan, NASA still had not formed a unified opinion on the moon landing plan. After more than half a year of intensive research and detailed demonstration, the lunar orbit docking method was finally selected in 1962. Practice has proved that this plan is scientific and effective, and it is worth spending so much time to study and determine it. It made the manned moon landing a success without taking detours, and it also has important reference significance for the current US "return to the moon" plan.

The so-called lunar orbit docking method is to launch a spacecraft carrying three astronauts into the lunar orbit. Then two astronauts land on the lunar surface in the lunar module and conduct lunar exploration. The other astronaut remains in the command module-service module combination to orbit the moon and conduct scientific experiments. When returning, the two astronauts on the lunar surface start the ascent stage engine of the lunar module to fly into the lunar orbit and rendezvous and dock with the command module-service module combination. After the two astronauts enter the command module, they discard the ascent stage of the lunar module, leave the lunar orbit and return to the earth. Before re-entering the atmosphere, the service module is discarded, and only the command module splashes down in the Pacific Ocean. The advantage of this method is that it only needs to land a small lunar module on the lunar surface, but the success or failure of the orbital docking directly determines the life safety of the astronauts.

The Lunar Module Ascent Stage rendezvoused with the Command Module-Service Module combination in lunar orbit

The lunar module is jettisoned, and the command module-service module assembly prepares to return to Earth

The command module-service module combination entered orbit around the Earth and separated from the service module after making the final orbital correction.

Seeing this, some readers may ask: Why not use the direct landing method, that is, send the entire spacecraft directly to the lunar surface? In fact, scientists have already considered this method and believe that it is relatively simple and safe, but the requirements for the launch vehicle are too high, and large spacecraft may be trapped in the lunar dust when landing on the lunar surface.

The famous American aerospace expert von Braun and the Marshall Space Flight Center preferred another method - the Earth orbit docking method, which is to first launch several Saturn V rockets to send several parts of the large spacecraft into the Earth's orbit, and then dock them; the docked spacecraft uses its own engine to accelerate towards the moon; when close to the moon, the spacecraft turns direction, starts the engine to slow down, and finally lands on the lunar surface; when the work is completed, this stage of the engine is discarded, and the manned spacecraft part uses the ascent engine to leave the moon and return to Earth.

After many scientists repeatedly compared and analyzed the three most popular plans, the final conclusion was: the lunar orbit docking method could be realized in October 1967 at a cost of about US$7.7 billion; the earth orbit docking method could be completed in July 1968 at a cost of about US$9.2 billion; the direct lunar landing method required funds of about US$10.6 billion and was difficult to achieve before October 1968. Therefore, the lunar orbit docking method, which was not optimistic in advance, was finally determined to be the best way for manned lunar landing.

What are the advantages of the lunar orbit docking solution?

The advantages of using the lunar orbit docking solution in terms of technology, time and money are as follows:

Apollo manned spacecraft lunar landing route map

(1) Only a small lunar module is needed to land on the moon, thus avoiding the difficulty of landing the entire spacecraft on the lunar surface. The lunar module weighs about 14.7 tons, which the lunar surface can withstand and is also extremely beneficial for slowing down the spacecraft.

(2) The lunar module only needs to carry a small engine, so the amount of fuel can be reduced. This is also beneficial for leaving the lunar surface.

(3) During the return, since the lunar module can be jettisoned, the weight of the return module can be further reduced, thus simplifying the design of the service module. In addition, only the command module is re-entered for recovery, which is also beneficial for recovery.

(4) It is more economical than the direct lunar landing method and the Earth orbit docking method.

NASA held a press conference on July 11, 1962 to announce the final decision on the lunar landing plan. This press conference informed the outside world of the final approved lunar orbit docking lunar landing plan.

Why is the rocket that carries people to the moon so important?

During the Cold War, the United States and the Soviet Union launched a fierce competition in the field of manned lunar landing, especially in the development of heavy-lift launch vehicles, because launching a manned spacecraft requires a heavy-lift launch vehicle with a low-Earth orbit carrying capacity of more than 100 tons. In the end, the United States successfully developed and launched the Saturn V launch vehicle and achieved manned lunar landing, while the Soviet Union failed to land a man on the moon due to the four launch failures of the N1 heavy-lift launch vehicle.

"Saturn 5" is a three-stage liquid rocket. It is 110.64 meters long, with a maximum diameter of 10.06 meters, a takeoff mass of 2945.95 tons, a takeoff thrust of 34029 kN, a low-Earth orbit carrying capacity of 127 tons, and a Earth-Moon transfer orbit carrying capacity of about 50 tons. Its first-stage rocket uses liquid oxygen/kerosene as propellant, and is equipped with 5 F-1 liquid rocket engines, that is, 1 in the middle and 4 around, with a total thrust of 34029 kN; the second stage uses liquid oxygen/liquid hydrogen as propellant, and is equipped with 5 J-2 hydrogen-oxygen liquid rocket engines, 1 in the middle and 4 around, with a total thrust of 5148 kN; the third stage also uses liquid oxygen/liquid hydrogen as propellant, and is equipped with a J-2 engine with a thrust of 902 kN.

The Saturn V Heavy rocket is ready for launch

After the Saturn V launched the last Apollo spacecraft, Apollo 17, on December 7, 1972, the heavy rocket launched the first U.S. space station, Skylab, into orbit on May 14, 1973. After that, this "giant" was retired because it had no use.

What did the Apollo lunar spacecraft look like?

After the moon landing plan was determined, the development of a new manned spacecraft became the "highlight" of the moon landing project. "Apollo" is the first and only moon landing spacecraft launched by humans, and its conception is very ingenious. Its technology also has important reference value for the construction of the moon base and manned Mars exploration that will be carried out today.

Apollo is 29 meters tall and weighs about 50 tons. It consists of a command module, a service module and a lunar module. There is also a life-saving tower during the launch ascent phase. The command module, which is similar to the return module of a satellite-type spacecraft, is where astronauts live and work, and is also the control center of the entire spacecraft; the service module, which is equivalent to the propulsion module of a satellite-type spacecraft, is equipped with the main engine, attitude control and electrical systems; the special lunar module consists of a descent stage and an ascent stage, which are used to land on and leave the lunar surface.

Apollo manned lunar spacecraft structure

The command module is conical, 3.5 meters high, 3.9 meters in diameter at the bottom, and weighs about 6 tons. The cabin is filled with 34.3 kPa of pure oxygen and the temperature is maintained at 21℃~24℃. It is further divided into the front cabin, the astronaut cabin and the rear cabin. The front cabin is used to place landing components, recovery equipment and attitude control engines. The astronaut cabin is a sealed cabin that contains necessities and life-saving equipment for astronauts to live for 14 days. The rear cabin is equipped with 10 attitude control engines, various instruments and tanks, as well as attitude control, guidance and navigation, onboard computers and radio subsystems. In the center of the command module, the seats for the commander, the pilot and the flight engineer are arranged side by side. When the spacecraft is launched and returns to the ground, the three astronauts lie on the chairs, and the astronauts can move around without seats at other times.

Command Module

The service module is a 6.4-meter-high, 4-meter-diameter cylinder weighing about 25 tons. It is equipped with trajectory change propellant, main engines, and three hydrogen-oxygen fuel cells. The thrust of the trajectory change main engine is 95.6 kilonewtons, which can send the spacecraft back to the ground from the lunar orbit. The front end of the service module docks with the command module, and the rear end has the main engine nozzle of the propulsion system. The module is divided into 6 compartments, which respectively accommodate the main engine, attitude control system, etc. The attitude control system consists of 16 small rocket engines. They are also used for the separation of the spacecraft from the third-stage rocket, the docking of the lunar module with the command module, and the separation of the command module from the service module.

The lunar module weighs 14.7 tons, has a diameter of 4.3 meters and is about 7 meters high. It consists of a descent stage and an ascent stage. The descent stage consists of a descent engine, four landing legs and four instrument cabins. It is used to land from the lunar orbit to the lunar surface and can send two astronauts to the moon. The ascent stage is the main body of the lunar module, which consists of an astronaut cabin, a return engine, a propellant tank, an instrument cabin and a control system. During the lunar landing process, the two astronauts live and work here. After completing the mission, the astronauts take the upgrade to return to the lunar orbit and meet the command module.

The Apollo 9 spacecraft carried the lunar module for the first time and conducted separation and docking tests.

The Apollo spacecraft used the Mercury spacecraft's launch life-saving system, which was designed to eject and safely recover the command module if an emergency occurred within 20 seconds before the second stage of the launch vehicle began to operate.

After the spacecraft was developed, it carried out six unmanned suborbital and circumorbital flights, one circumnavigation of the Earth, and three manned circumlunar flights before finally officially carrying out a lunar landing flight.

Is driving on the moon the same as on Earth?

From July 1971 to December 1972, the United States launched the Apollo 15, 16 and 17 manned lunar spacecraft. Each of them was equipped with a foldable manned lunar rover and was basically the same. Both could travel in the low-gravity and vacuum environment of the moon, thus expanding the astronauts' extravehicular activities.

Apollo 17 astronauts perform extravehicular activity

Each lunar rover weighs about 210 kg, is 3 meters long, has a wheelbase of 2.3 meters, and is 1.1 meters high. It has four wheels (each wheel is driven by an engine and powered by batteries, and the tires can remain elastic at low temperatures of -100°C). The power supply uses silver-zinc potassium hydroxide disposable batteries. The driving speed is 10 to 12 kilometers per hour and can carry a payload of about 490 kg. The vehicle is equipped with two foldable seats side by side, each with adjustable pedals and seat belts. A large mesh dish antenna is installed on the front mast of the vehicle. Astronauts control the rover through a T-shaped manual controller located between the two seats. There is a control and display module in front of the handle to display the current speed, direction, power supply and temperature.

Astronauts train to drive the lunar rover at a simulated lunar surface geological site

The lunar rover can reach a maximum speed of 16 kilometers per hour. Astronauts drive it across the lunar surface, use the vehicle as a means of transportation, climb over obstacles, cross ravines, survey mountains, canyons and craters, and transmit exciting color images back to the ground.

The Apollo 15 rover traveled a total of 27.76 kilometers in 3 hours and 2 minutes, collecting about 77 kilograms of lunar samples. The Apollo 16 rover traveled a total of 26.55 kilometers in 3 hours and 26 minutes, collecting about 96 kilograms of lunar samples.

The Apollo 17 lunar rover traveled a total of 35.89 kilometers in 4 hours and 26 minutes, collecting 111 kilograms of lunar samples. During the Apollo 17 mission, the astronauts drove the lunar rover the longest distance, as the reliability of the lunar rover and space suits increased, alleviating the limitations of the lunar rover's driving distance.

When astronauts use the lunar rover, they will be affected by very fine lunar dust particles. The lunar dust will cause wear and tear on bearings, gears and other mechanical structures such as seals. In addition, when the lunar rover is driving, due to the small gravity on the lunar surface, a huge amount of dust is splashed from under the wheels, with a height of more than 2 meters, which has a certain impact on the astronauts' patrol mission.

Astronauts drive the lunar rover freely on the moon

The entire Apollo project relied on the above-mentioned tools to realize the dream of human landing on the moon.