Flying in orbit for 50 years has opened a new era of space flight.

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From the first artificial satellite to the Samsung rocket, from unmanned spacecraft to astronauts' extravehicular activities, from the probe flying around the moon to the soft landing on the back of the moon, China's space industry is striding to the forefront of the world. In 2020, Beidou-3 is expected to realize global networking and put Mars exploration on the agenda. China people are gathering strength to advance to higher goals in the journey of understanding and exploring space.

The picture shows that at the beginning of 1970, researchers tested the Dongfanghong-1 satellite in the factory building. Photo courtesy of NASA.

1970 On April 24th, China's first carrier rocket Long March-1 was successfully launched with China's first artificial earth satellite Dongfanghong-1, which ushered in another milestone in China's space history, and this was also the origin of China's space day. Today, on the occasion of the fifth China Aerospace Day, let's review the history of the development and launch of Dongfanghong-1, the development process of China's space industry from scratch, and remember and carry forward the eternal space spirit.

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April 24th, the fifth China Aerospace Day. This day is also the 50th anniversary of China's first artificial earth satellite, Dongfanghong-1, entering space.

1970 On April 24th, at Jiuquan Satellite Launch Center, Dongfanghong-1 satellite roamed the space with the roar of China's first launch vehicle Long March-1. China has since become the fifth country in the world to independently develop and launch artificial satellites, and China people have since knocked on the door of the vast universe.

Today, Dongfanghong-1 satellite is still flying around the earth. On sunny days, many astronomy enthusiasts will also take photos of this satellite flying over the motherland. These photos bear an unforgettable and eternal story.

Concentrate scientific research strength

Get on the space stage

In May, at the second meeting of the Eighth National Congress in the Communist Party of China (CPC), President Mao Zedong issued the call of "We also want to build satellites".

"This call declares that the Chinese nation has confidence and courage to board the stage of space activities." Pan Houren, then deputy head of the overall design team of Dongfanghong-1 satellite, recalled.

1967, China named the first satellite Dongfanghong-1 and the first launch vehicle Long March-1. Dongfanghong-1 satellite is a scientific exploration experimental satellite. It has a spherical 72-sided shape with a diameter of 1 m and a weight of 150 kg. It is planned to be launched around 1970. The mission of this satellite is to lay a technical and practical foundation for China to develop various application satellites such as Earth observation, communication broadcasting and weather forecast in the future.

1968 On February 20th, China Academy of Space Technology was formally established, with Qian Xuesen as its president and Dongfanghong-1 satellite developed by China Academy of Space Technology.

Launching an artificial earth satellite is a huge and complex system engineering, involving scientific research, production, launch, measurement and control and other fields. "It is very simple now, but there is a gap between the industrial level and the technological level of that era." Sun Jiadong, who was ordered to lead the satellite development, described this.

With the continuous modification of the design scheme, the weight of Dongfanghong-1 satellite has increased from the initial 150kg to 173kg, far exceeding the sum of the first four satellites in the world. It is difficult to send such a heavy satellite into space. Qi Faren, then one of the technical directors of Dongfanghong-1 satellite, said that the satellite must also meet the four technical requirements put forward by the state, namely, "being able to climb, grasp, listen and see".

In order to accomplish this arduous task, researchers began a difficult exploration to pursue their dreams.

overcome difficulties

Complete the four major goals

"Get up, grab, listen and see", 12 summarizes the overall technical scheme and objectives of Dongfanghong-1 satellite, and also summarizes the technical difficulties.

The first consideration is whether you can "get up". According to the plan, Dongfanghong-1 satellite will run in an elliptical orbit with a perigee of more than 400 kilometers and an apogee of more than 2,300 kilometers. In order to put the satellite into orbit accurately, the launch vehicle responsible for carrying the satellite must have strong propulsion capability.

Experts put forward the "two combination" scheme: using medium and long-range missiles as the first and second stages, and using sounding rocket technology to develop the third stage. Through the continuous transmission of these three stages, the satellite is put into the predetermined orbit. Under the leadership of Ren Xinmin, who was in charge of rocket technology at that time, the launch vehicle officially entered the development stage, and finally realized the perfect combination of missile technology and sounding rocket technology, which solved the problem of "getting up and leaving" and made the phrase "the space stage is as big as the launch vehicle's ability" widely circulated.

If you want to "catch" a satellite on the ground, you must always grasp its position in space, which requires calculating the distance between the satellite and the ground. After comparing several schemes, the experts decided to adopt the Doppler principle-measuring the speed according to the change of radio wave frequency, and then measuring the distance. However, this solution needs a special equation, which is a difficult problem for scientists in China at that time.

In this regard, the researchers of Dongfanghong-1 satellite changed their design ideas, reconstructed the satellite orbit determination equation, and solved the problem of the satellite orbit determination equation, so that the position of the satellite in space can be monitored at any time.

Next, people focus on "listening" and "seeing".

At that time, it was very difficult for satellites to play the music of Dongfanghong in space. The developer replaced the "keys" with six highly stable sound source oscillators, and controlled the pronunciation with the beat generated by the program-controlled circuit. After hundreds of tests, it was finally ensured that Dongfanghong No.1 played "Dongfanghong".

Hu, a member of the overall team of Dongfanghong-1 satellite, mentioned that in order to let ordinary radios receive the music from the satellite, everyone proposed a "relay" method. "We can't directly hear the music played by Dongfanghong-1 satellite on the ground. We need to send it through a satellite antenna, receive it at the ground station, and then broadcast it on the radio. " Qi Faren recalled.

The last difficulty is "looking". If you want to see the satellite running in space with the naked eye, its brightness must rise from the seventh star to the fourth star. Not only that, the diameter of Dongfanghong-1 satellite is only 1 m, which is even more difficult to "see". Finally, the developer found inspiration from the characteristics of the folding umbrella and decided to install an "observer" made of high reflective brightness material in the third stage of the launch vehicle, which can be opened in space. Because this "observer" is huge and has extremely high reflection brightness, people can directly observe it.

Solve world problems

Create a new record

There is still an unavoidable problem on the way to heaven, that is, satellites must withstand the test of extreme temperature changes in space.

In space, the temperature on the sunny side of the satellite can be as high as 100 degrees Celsius, while the temperature on the back can be reduced to-100 degrees Celsius. How to maintain the normal "body temperature" of satellites in space is a recognized problem in the world.

Technicians have developed a complete temperature control system to balance the temperature inside the satellite, but the normal operation of the system requires a lot of electricity, and the power carried by the satellite is very limited. Finally, the researchers came up with a zero-power scheme for the temperature control system: using the heat generated by other instruments to help the satellite control the temperature, which skillfully solved the problem of high power consumption.

Overcome all kinds of difficulties and successfully complete the development of satellites and launch vehicles.

After four days and four nights of trekking,1February, 970, Dongfanghong-1 satellite and Long March-1 carrier rocket arrived at Jiuquan Satellite Launch Center.

1On April 24th, 970, the countdown to launch was minus 8 hours, and the sudden news of "unstable measurement and control signal" made the technicians on site nervous again.

Where does the interference signal come from? People lock the source of the problem at the connection between the satellite and the rocket. In order to meet the requirements of temperature control, an aluminized film is wrapped around the instrument at the joint of rocket and satellite, which shakes due to improper fixation, resulting in unstable signal. After fixation, the problem was solved. At this time, the dark clouds in the sky disappeared, the sun shone on the body of the launch vehicle, and the time for take-off finally arrived.

Dongfanghong-1 satellite, which accurately entered the scheduled earth orbit, has been in orbit for 24 days, which not only successfully passed the test of the extreme environment in space, but also successfully achieved the requirements of "getting on, grasping, hearing and seeing". As the weight of Dongfanghong-1 exceeded the sum of the first satellites of the first four countries, it also set a new record in human space history.

"By persisting in self-reliance and hard struggle, we overcame all the impossibilities and finally successfully sent the Dongfanghong-1 satellite into space." Qi Faren said.

The successful launch of Dongfanghong-1 satellite was an important event that shocked the world in the 20th century, which announced the rise of an oriental space power. Dongfanghong-1 satellite, together with nuclear bombs and missiles, is called "two bombs and one satellite", which has become an important symbol of the strategy of strengthening the country through science and technology and has been recorded in the history of the great rejuvenation of the Chinese nation.

If you want to know more about "Dongfanghong-1 flies into a new era of space after 50 years in orbit", please continue to pay attention to the column of deep space science and technology information, and deep space Bian Xiao will continue to update you with more science and technology news.

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