While carrying out manned space flight, korolev began its efforts to fly out of the earth. Of course, the moon closest to the earth is the first landing target for human beings to go into space. In order to land on the moon, at least three people need to take the same spaceship, so the size and weight of the spaceship are much larger than that of the Dongfang, which carried an astronaut before. In addition, the distance to land on the moon is much farther than that of orbiting the earth, so the thrust of the rocket must be much larger than that of the previous R-7. Korolev began to improve the R-7 in 1958. However, due to the political turmoil in the former Soviet Union, he was short of funds, and his work encountered many troubles. In 1959, Luna, the first spacecraft of the former Soviet Union to explore the moon, was supposed to touch the moon, but in the end it was 6,000 kilometers off the scheduled orbit. Fortunately, Lunar Exploration II was a success, becoming the first human aircraft to reach the moon, and korolev won the first place in the world for the former Soviet Union. The third ship went one step further. It sent back photos of the back of the moon.
Sergei korolev, the father of space flight in the former Soviet Union
According to korolev’s plan, it is a matter of time before the Soviet Union landed on the moon, and it should be before the Americans. In order to meet the needs of landing on the moon, korolev put forward a new design scheme and long-term planning for a large rocket, which is the famous N1 launch vehicle of the former Soviet Union. N1 also has two little brothers N2 and N3, whose size and thrust are gradually reduced, and the latter is used to carry intercontinental missiles. However, just after the design scheme of N1 was released, before it was implemented, the former Soviet Union was caught in a debate about whether to give priority to the development of intercontinental missiles or manned rockets. In December, 1959, after intense discussions among officials in charge and experts at all levels, the idea of giving priority to missile development prevailed. In this case, there is no need to build a super-large rocket like N1. Although korolev has also obtained some funds to continue to develop rockets for landing on the moon, the former Soviet Union’s moon landing plan has temporarily stalled.
At the same time, the White House ushered in a new owner, and the United States also entered their new era. The balance of the space race began to tilt in favor of the United States.
On January 20, 1961, snow covered Washington, the capital of the United States. The youngest president in American history, only 43-year-old John F. Kennedy, was sworn in in front of the White House. A few months ago, he defeated Nixon, the then vice president, in the general election, and the two men always could not avoid a controversial topic-how to defeat the Soviet Union in the Cold War. American efforts began with President Eisenhower, and Nixon, then vice president, did a lot of work. However, the youthful Kennedy was much more ambitious than his predecessor. In Kennedy’s famous inaugural speech, he put exploring the mysteries of interstellar space as the first priority in his scientific work, before conquering deserts and treating diseases. And he called on the United States and the Soviet Union to join hands in these fields. Only four months later, Kennedy put forward an ambitious space program-landing on the moon within ten years. This program was named after the sun god, which is the famous Apollo Program.
Von Braun is with President Kennedy.
The Apollo program is the largest plan for human beings to explore space and unknown areas, and the whole country in the United States has mobilized. Hundreds of universities, research institutions and companies, more than 20,000 scientists and 400,000 people directly and indirectly participated in this space program. The key to the Apollo program is the development of the rocket to the moon, and the popular candidate is von Braun. Therefore, when the project was about to begin, von Braun and his team transferred from the Army to NASA. Von Braun served as the director of Marshall Space Center, responsible for the development of rockets to the moon, the project code-named Saturn. Von Braun’s new job began in 1961, and he was fighting against his unknown opponent in the Soviet Union.
Von Braun, praised by NASA as the first person in the history of world space.
Compared with korolev, von Braun is much luckier. The United States is more secure in financial resources and manpower than the former Soviet Union, so Americans catch up quickly. In 1961, von Braun’s Saturn I rocket was successfully developed, which was the first large thrust rocket made in the United States. The thrust of the first stage rocket reached 6670 kn, exceeding the thrust of all R-7 engines. Generally speaking, Saturn-1 was very successful. It not only successfully put five spacecraft, including command module and service module, into Earth orbit in 1964-1965, but also sent some satellites related to the Apollo program and microwave survey ships between the Earth and the Moon (to prepare for the subsequent communication on the moon) to the scheduled orbit.
The three astronauts of Apollo 11 reunited in front of the lunar module that year.
NASA originally planned to use Saturn-1 to carry out four manned space flights in 1965-1966, but later it was found that the thrust of the rocket was slightly insufficient, so von Braun developed a Saturn-B rocket with stronger thrust in 1963. The thrust of its first-stage rocket was about 10% higher than that of Saturn-1, and the thrust of its second-stage rocket was more than doubled (890 kN to 400 kN). So far, the United States In addition to rocket technology, there are many cutting-edge technologies needed for landing on the moon. Let’s take a look at the preparations made by Americans on several key technologies.
The first is the technology of landing and leaving the moon.It is not easy for astronauts to land on the moon safely. On the earth, with the help of the atmosphere and the ocean, we can slow down the capsule that is about to land by parachute, and we can also land on the ocean in order to prevent the capsule from colliding with the ground. Unlike the earth, the moon has neither atmosphere nor ocean, so these methods of landing on the earth are not used on the moon. The only way is to slow down the lunar module with a reverse rocket, just like what we saw in the movie Star Wars and various science fiction films. But in reality, it is very difficult to do so, and the rocket jet speed and angle must be controlled very well.
Of course, astronauts are neither Chang ‘e nor WU GANG, so they can’t live on the moon for a long time, and they still need to leave the moon and return to Earth. At the beginning of the Apollo program, NASA proposed four return schemes.
The first plan is to take a big rocket with the lander, and the United States is the smallest.
The fourth scheme is to launch two rockets to the moon, one carrying the lunar module and the other carrying the rocket returning from the moon to the earth, and then assemble it on the moon. The disadvantage of this method is that if the trajectories of the two rockets deviate a little, the landing point of the lunar module and the returning rocket will be 180 kilometers or more, and the astronauts will not come back.
Most experts prefer the first scheme because it is simple. At that time, most experts were not sure about air docking. In fact, von Braun also supports this scheme, and has planned to design a Nova rocket (nova) larger than Saturn V to accomplish this mission. However, a scientist named John Houbolt (1919-) insisted that the total weight of lunar landing equipment should be as light as possible, and tried his best to convince most people, so experts including the Marshall Space Center led by von Braun accepted the third scheme. The Apollo program finally adopted this scheme and achieved success. American historians believe that it would not have been possible to land on the moon in the late 1960s if NASA had not finally adopted the opinions of a few people, although Americans were able to land on the moon in the end.
Of course, one of the difficulties of this plan is docking. For this reason, Apollo 9 conducted a docking test in orbit around the earth, and the test was successful. Only then did the Americans move on.
Secondly, the technology of the moon landing spacecraft..Spacecraft landing on the moon include Command and Service Module (CSM) and Lunar Module (LM). As shown in the figure below:
The three parts of Apollo 11, from left to right, are the service module, the command module and the lunar module.
The command module is the shelter for astronauts on their way back and forth. It is not only to send astronauts from the earth to the moon orbit, but also to return them, and it is also the only part that re-enters the atmosphere to send astronauts to the surface, so it has been tested the most in the Apollo program. This module is about three and a half meters in diameter, nearly four meters high and weighs 5.5 tons. The service module (SM) is connected with the command module (CM, sometimes called the space module in the news), and its diameter is similar to that of the command module, but its length is seven meters. It transports all kinds of materials needed for landing on the moon, including liquid fuel and various equipment, weighing 24 tons. The service module is connected to the command module and flies to the moon together, but it will be thrown away when the spacecraft re-enters the earth’s atmosphere. Most of the time, the service module and the command module are tested together. The part of landing on the moon includes the thrust rocket needed for landing on the moon and the rocket leaving the moon, as well as the lunar module. Although the weight of this part has been reduced as much as possible in the design, it still weighs 15 tons.
Then there is the control technology.One of the most critical technologies is the Kalman filter in automatic control. This filtering method was invented by Rudolph E. Kalman (1930-), an American Hungarian mathematician. At the beginning of this control theory put forward by Kalman, its practicability was so doubtful that he did not publish this achievement in the journal of electronic engineering and automatic control, but published it in the journal of mathematics. One day in 1960, Kalman visited Stanley Schmidt (1944-), who worked in NASA, and found that his method was very useful for solving the difficult problem of orbit prediction in Apollo program, so he taught it to Schmidt.
Finally, there is the problem of communication between the earth and the moon.The moon is 380 thousand kilometers away from our earth, nearly 10 times the circumference of the earth. Such long-distance two-way communication has never been carried out by humans before. Will the attenuation of the signal interrupt communication? In addition, it takes more than two seconds for radio waves to travel back and forth between the earth and the moon once. How to eliminate the influence of this delay on control? There are many problems that need to be tested one by one to determine. To this end, the United States launched some spacecraft to test the communication between the earth and the moon. Finally, Motorola provided intercom equipment between the moon and the earth. Unfortunately, this great company no longer exists independently today.
In the race to the moon, the former Soviet Union was far behind the United States in key technologies except rocket technology.
Of course, in the end, everything will go back to the rocket, because the total weight of several parts of the whole moon landing spacecraft exceeds 45 tons, which makes the manufacture of large thrust rockets become the bottleneck of the whole plan. Von Braun’s team needs to design a rocket with much larger thrust than Saturn-B. The previous dozens of various launch tests undoubtedly provided rich technical accumulation for their later development of new rockets. In 1967, von Braun’s masterpiece Saturn V was born.
But in January 1967, Apollo 1 had an accident before it was launched. In a ground test, the oxygen cabin exploded and the spacecraft caught fire, killing all three astronauts. The accident did not shake the determination of Americans, but helped Americans find many problems and make a lot of improvements, from the design of spacecraft to the spacesuit. Some of these improvements benefited the later Apollo 13 and avoided new tragedies. Although the Apollo program was slightly delayed, in November, Apollo IV (to commemorate the three astronauts who died, Apollo 1, 2 and 3 were vacant) was successfully launched, which was the first test of Saturn V rocket. In the following six months, the United States conducted two more experiments and tested all the links needed for landing on the moon in an unmanned state. After half a year’s preparation, from October 1968, the United States began to use manned spacecraft (Apollo VII) for simulation experiments. In just seven months, the United States conducted as many as four experiments, and 12 astronauts went into space. Among them, Apollo 8 manned the lunar orbit for the first time, and three astronauts circled the moon for 10 times. Apollo 10 tested the landing process of the spacecraft to the moon and landed at a height of only 15,000 meters from the surface of the moon, which is only slightly higher than the cruising altitude of commercial aircraft.
The next task is to land on the moon and let the astronauts set foot on the surface of the moon. For the first trip to the moon, NASA made full preparations. In the early stage, I launched many experiments and tried everything I could think of. The rest is to determine the candidate for the first moon landing mission. After many considerations, Neil A. Armstrong (1930-2012), Edwin E. Aldrin (1930-) and Michael Collins (1930-) were finally determined to perform this historic mission. Of course, to be on the safe side, NASA has also prepared a corresponding backup team. Even after selecting a three-person team, who will set foot on the moon first has become the focus of controversy among several astronauts. In training, Aldrin climbed out of the hatch first, and finally changed to Armstrong, because the design of the hatch was more convenient for him rather than Aldrin going out first. For the inside details of Apollo’s landing on the moon, readers can refer to the book Apollo-Lunar Expedition.
Soon, a glorious moment in human history came. On July 16, 1969, at the Kennedy Space Center in Cape Canaveral, Florida, Armstrong and others boarded the towering Apollo 11 spacecraft and were about to begin the human journey to the moon. The Apollo landing on the moon was televised by the United States to the whole world, and Nixon, then president, watched the live event on TV from the Oval Office of the White House. I think that if every reader can go back to that day, he will definitely sit in front of the TV and watch it. Fortunately, more than 30 years later, in the command room of Kennedy Space Center, I saw the command of Apollo 11 mission and the video of landing on the moon at the simulation site.
Ok, now please follow me to the command center. At 9: 32 am (Eastern Daylight Time), the rocket launch entered the final countdown. Astronauts and rockets are in good condition. Perhaps out of excitement or nervousness, Armstrong’s heart rate reached 110 beats per minute when the rocket was launched, which had never happened before. On the console, the display screens and lights of various instruments kept flashing, and the timer on the wall began to count down-10, 9, 8…3, 2, 1. At this time, the sound of "emission" sounded in the background. On the big screen, Saturn V ignited successfully, and the orange flame pushed the 110-meter-high behemoth to rise slowly and faster until the rocket disappeared on the screen. On the fourth day, July 19, the rocket entered the lunar orbit; On the fifth day, July 20th, Apollo 11 was ready to land on the moon. The camera switches to the image of Apollo 11 landing on the lunar surface, and there is a camera under the lunar module, which sends the blurred image of the lunar surface back to Earth. I saw the lunar module getting closer and closer to the surface of the moon and finally stopped there. This image can be seen on the website of NASA. After the lunar module landed safely on the surface of the moon, commander Armstrong returned the first words that humans said on the moon: "Houston, this is the Jinghai base. The eagle landed successfully. "
Next, Armstrong and Aldrin should sleep for five hours according to the pre-set itinerary, because they didn’t sleep much during the flight. But both of them were so excited that no one could sleep. After consulting the headquarters, they set foot on the surface of the moon in advance. On the screen of the control room, Armstrong stepped down from the lunar module and set foot on the moon. His movements were very slow. Because of the long distance and the communication technology is far less developed than today, the images and sounds sent back are intermittent, but Armstrong’s famous words can still be distinguished, "This is one small step for man, but one giant step for mankind." The recording of these seconds can be heard on the Internet.
Aldrin is on the surface of the moon.
More than 600 million viewers around the world watched the first human step on the moon on TV. Armstrong and Aldrin put some experimental instruments on the surface of the moon and collected more than 20 kilograms of lunar rock samples. The two of them stayed on the moon for about two and a half hours, and then went back to the lunar module to sleep. Although Aldrin accidentally broke the ignition switch of the return rocket, it was near miss. They turned on the switch with a pen, and the rocket sent them to the lunar orbit to rendezvous with the control/service module, and then returned to Earth. On July 24th, the command module carrying three astronauts fell into the Pacific Ocean. The whole process from launch to safe landing on the earth’s surface is about eight days and three hours.
Armstrong and other three astronauts spent more than ten days in the isolation cabin after returning from the moon. At that time, American President Nixon visited them in the isolation cabin at the first time and congratulated them through the glass window.
The success of Apollo’s landing on the moon is a victory for all mankind. As many as 400,000 people directly and indirectly participated in the Apollo program (Nixon’s original words). They came from different countries in the world, including many Chinese scientists. How much contribution did von Braun make in the Apollo program? NASA commented on him like this: "There is no doubt that he is the greatest rocket scientist in history. His greatest achievement was that when he was the director of the Marshall Space Flight Center of NASA, he presided over the research and development of Saturn V and successfully achieved the great cause of human landing on the moon for the first time in July 1969. " It can be said that there would be no Saturn V without von Braun. Although humans can finally land on the moon, it will not be within the time limit set by Kennedy-the 1960s.
On January 12th, 1966, korolev died of a surgical operation at the age of 59. It’s a pity that he didn’t see the successful docking of his designed spacecraft Soyuz and Salute-he had been buried underground for more than four years.
Vasily Mishin (1917-2001), korolev’s successor, did not have the influence and courage of korolev. Although he completed the development of the N1 rocket under very difficult circumstances, the rocket failed in all directions. Coupled with the constant space accidents, especially the death of astronauts, the Soviet Union’s moon landing plan failed as a whole and was finally abandoned.
In the end, Americans successfully landed on the moon many times, but the former Soviet Union did not once. The fundamental reason for this is not that korolev’s ability is not good, but that the former Soviet Union lost in its comprehensive national strength.
Without his opponent, von Braun continues to devote himself to the space industry. After Apollo 11, the United States successfully landed on the moon five times, completing a feat in human history. In 1972, after achieving the expected goal, the United States terminated the Apollo program and developed a reusable space vehicle, the space shuttle. Five years after the last Apollo spacecraft landed on the moon, von Braun also came to the end of his life. In 1977, he died of cancer. Shortly before his death, he won the National Science Award, the highest award in American science and technology, but he was unable to go to the White House to receive the award.
(This article is taken from the second volume of Light of Civilization, written by Wu Jun, People’s Posts and Telecommunications Publishing House, 2014). )
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