Why is China's first artificial earth satellite "Dongfanghong-1" still running in space?

In the past 2020, China's space industry has achieved fruitful results. Although the activities in China were affected by the COVID-19 epidemic at the beginning of this year, with the joint efforts of the people of the whole country, we achieved a staged victory in fighting the epidemic. This year, China Aerospace started the "super mode" again: successfully implemented the first sampling and returning of extraterrestrial objects by Chang 'e-5, completed the deployment of Beidou-3 satellite navigation system and provided services to the world, and headed for Mars by Tianwen-1 probe. .......

A series of major space events have effectively promoted the construction of a space power, and at the same time attracted widespread attention all over the world. Half a century ago, the launch of Dongfanghong-1 satellite opened the curtain for China people to explore the mysteries of the universe. Half a century later, Chang 'e V completed the first sampling of extraterrestrial objects. What are the stories behind the successful launch of the landmark Dongfanghong-1 in China's space history? Where is Dongfanghong No.1 now? Now we take these questions to review the past life, China's first artificial earth satellite.

1957 10 10 On 4 October, the Soviet Union successfully launched the world's first artificial earth satellite, and then the United States, France and Japan successively launched their own artificial satellites. 1958 On May 17, President Mao Zedong proposed at the second meeting of the Eighth National Congress in communist party, China, "The Soviet satellite is in the sky, so we should also build satellites. If we want to do it, we should make it bigger. " 1960 on February 9th, China's first self-made liquid fuel sounding rocket T-7M was launched in Shanghai, but it only flew 8 kilometers.

Of course, the short eight kilometers can't be compared with our rockets today, but the pioneering significance of this short eight kilometers in China's space history can't be underestimated. At that time, Chairman Mao commented: "Great, eight kilometers is also great, so we will do it, eight kilometers, twenty kilometers, two hundred kilometers." From 65438 to 0964, China successfully launched its first ballistic missile and exploded its first atomic bomb. This series of progress laid the foundation for the development of artificial satellites, and the satellite program began to be put on the agenda again.

1965 1.8 Qian Xuesen suggested that China's suspended artificial earth satellite be re-launched and included in the national task. Qian Xuesen's suggestion was endorsed by Vice Premier Nie. In May of the same year, Premier Zhou Enlai instructed China Academy of Sciences to come up with a specific plan for the 1 satellite. Qian Ji, who is in charge of the whole satellite group, led young scientists and technicians to put forward a preliminary plan soon. 1In July, 965, the meeting of the Central Special Committee chaired by Premier Zhou Enlai approved the Proposal of China Academy of Sciences on the Work Plan of Developing China's Artificial Satellite.

At the end of 1965, the Academy of Sciences began to discuss satellite development and measurement and control, and finally decided not to follow the path of the United States and the Soviet Union, but to take a multi-pronged approach of optics, radar and radio Doppler measurement. 1966 70 1 engineering office responsible for satellite tracking and measurement was formally established. 70 1 Engineering Department has concentrated talents in astronomy, electronics and optics. Because the longitude span of China is far less extensive than that of the Soviet Union, it is relatively difficult to locate the monitoring station. At that time, it was estimated that the second lap of the satellite would be over Xinjiang and return to the eastern coast after a dozen laps.

So at that time, eight stations and 1 monitoring centers were set up in Kashgar, Northeast China and Jiaodong. In terms of satellite design, Qian Ji led the team to quickly draw up a preliminary table of three diagrams: main technical parameters and analysis diagram of the satellite, satellite trajectory diagram and satellite outline diagram. 1In August, 1965, Premier Zhou personally presided over a meeting of the Central Satellite Special Committee and decided to code the satellite project as 65 1. 65438+1October 20th to165438+1October, the first demonstration meeting on the overall scheme of artificial satellite was held in Beijing. The meeting decided that the mission of the satellite is to develop China's experience in the fields of Earth observation, communication and broadcasting, and meteorology.

The launch time of the satellite is set at 1970. At the same time, the meeting also put forward four requirements: going up, grasping, listening and watching. The biggest controversy at this meeting is the weight of the first satellite: the first satellite of the Soviet Union is 83.6 kilograms, and each first satellite is only 7 kilograms. Our goal is about 100 kg, but with the joint efforts of satellite and rocket technicians, the actual weight of "Dongfanghong-1" has reached 173 kg. The name of "Dongfanghong-1" and the determination of playing music mainly refer to the experience of using discontinuous signals by Soviet satellites.

He, the head of the overall team at that time, said: "Soviet satellites use discontinuous signals, and we want to surpass the Soviet Union. Therefore, to transmit continuous signals, the transmitted signals must highlight the characteristics of China. It is suggested to use china national radio's external call sign' Dongfanghong' music ". 1966 in may, China's first artificial earth satellite was named "dongfanghong-1" after being jointly agreed by the commission of science, technology and industry for national defense, the academy of sciences and the seventh machinery department and reported to the central government for approval. At the beginning of 1967, the music played by China's first artificial earth satellite was determined to be "Dongfanghong".

1970 at 2 1 35 on April 24th, the Long March-1 carrier rocket carrying Dongfanghong-1 was successfully launched at Jiuquan Satellite Launch Center. At 2 1: 50, the National Broadcasting Bureau reported that it had received the clear and loud music "Dongfanghong". The successful launch of Dongfanghong-1 ushered in a new era in China's space history: China became the fifth country in the world to independently develop and launch artificial earth satellites after the Soviet Union, the United States, France and Japan. Due to the limited battery life, the design life of "Dongfanghong No.1" is only 20 days, but in fact, "Dongfanghong No.1" has been working for 28 days.

1970 May 14, Dongfanghong-1 satellite stopped transmitting signals; However, the orbital life of the satellite is not over. In fact, Dongfanghong-1 is still running in space. Today, on sunny days, astronomy enthusiasts can still take photos of this satellite flying over the motherland. Some experts estimate that according to the current trend, Dongfanghong-1 should be able to run in space for hundreds of years. Why didn't the "Dongfanghong No.1" that had stopped working crash? You know, the Soviet Union's first artificial earth satellite crashed after only 92 days in space.

Most artificial earth satellites in other countries are almost as bad as those in other countries. Tiangong-2 Space Laboratory, launched by China in 20 16, was also controlled to fall into the atmosphere in July 20 19. In the friction with the atmosphere, most of the structure of Tiangong-2 was burned, leaving only a small amount of debris falling into the scheduled waters of the South Pacific. It is said that after nearly half a century's development, the technical advantage of Tiangong-2 far exceeds that of Dongfanghong-1, so what makes Dongfanghong-1 fly in space without power?

Why did China let Tiangong-2 fall into the atmosphere? The main reason is that Tiangong-2 changed its orbit to a height of about 380 kilometers after its launch, and then dropped to more than 200 kilometers. The density of the earth's atmosphere generally increases exponentially with the decrease of altitude: the lower you fly, the greater the influence of the atmosphere on satellites. If the orbital altitude of the spacecraft is less than 300 kilometers, there is only one ending: falling into the atmosphere. Instead of letting it fall at will, it is better to let it fall into no man's land to ensure the safety of people's lives and property.

Dongfanghong No.1 is equivalent to a 7 1 sphere with a diameter of one meter, and its weight reaches 173 kg. We launched such a big guy into the sky at one time, and also used the big thrust of the rocket to launch the satellite into a higher orbit, so the gravity of the earth is smaller than other satellites. When Dongfanghong-1 was launched, the perigee altitude was 439 kilometers and the apogee altitude was 2384 kilometers. Because the lowest altitude has exceeded 400 kilometers, there is almost no atmospheric impact.

By 20 17, the perigee height of Dongfanghong-1 became 429 kilometers, and the apogee height became 2036 kilometers. According to the current running trend of Dongfanghong-1, it may get closer and closer to the Earth under the gravity of the earth, so it will eventually fall into the atmosphere and be destroyed like Tiangong-2, but it may also gradually move away from the Earth because of its too fast speed, thus entering space. Of course, most spacecraft orbiting the earth will eventually fall into the earth's atmosphere and be destroyed, which may also be the final outcome of Dongfanghong-1.

Dongfanghong-1 uses silver-zinc batteries instead of solar panels of other satellites. Although the electric energy reserve of silver-zinc battery is limited, it is not as big as that of solar panels, so the satellite will not be subjected to too much windward force, and the larger windward force is only one of the reasons why the satellite falls faster. Solar panels and low orbit are the two main causes of satellite crash. "Dongfanghong No.1" escaped from these two places: not only the launch orbit was high, but also the silver-zinc battery was used.

"Dongfanghong No.1" is spherical in shape, thus reducing the resistance to a minimum. At that time, researchers designed the battery of Dongfanghong-1 to run out of energy after 20 days, but it worked for 28 days because of the spherical structure of the satellite. Now the first satellite launched by other countries has crashed, and only China's "Dongfanghong-1" is still soaring in space. Of course, we have the technology to recycle Dongfanghong-1, but isn't it more meaningful to keep this satellite carrying the original mission of China Aerospace flying in space?