Fifty years of on-orbit flight opens a new era of aerospace
The Flying Story of Dongfanghong No.1 (Decoding · China Aerospace Day)
From the first artificial satellite to the one-star Samsung, from the unmanned test spacecraft to the astronaut's space capsule, from the probe flying around the moon to the soft landing on the back of the moon ... China's space industry is striding forward to the forefront of the world. In 2020, Beidou-3 is expected to achieve global networking and Mars exploration on the agenda. The Chinese people are recognizing and exploring the space journey, accumulating strength and advancing towards higher goals.
On April 24, 1970, China ’s first launch vehicle, the Long March 1, was successfully launched with China ’s first artificial earth satellite, Dongfanghong-1. China ’s spaceflight history ushered in another milestone, and this is also the origin of China ’s space day. Today, on the occasion of the Fifth China Aerospace Day, let us revisit the history of Dongfanghong-1 research and development, review the development of China's space industry from scratch, from small to large, and remember and promote the long-lasting Space spirit.
April 24, the fifth China Aerospace Day. This day is also the 50th anniversary of China's first artificial earth satellite Dongfanghong-1 entering space.
On April 24, 1970, at the Jiuquan Satellite Launch Center, with the roar of China's first carrier rocket, the Long March 1, the Dongfanghong-1 satellite flew into the vast expanse of space. China has since become the fifth country in the world to independently develop and launch artificial satellites, and the Chinese have since knocked on the door to the vast universe.
Today, the Dongfanghong-1 satellite is still flying around the earth. On sunny days, many astronomy enthusiasts will also take pictures of the satellite passing over the motherland. These photos carry an unforgettable and time-honored story.
Concentrate on scientific research
Board the space stage
In May 1958, at the second meeting of the Eighth National Congress of the Communist Party of China, Chairman Mao Zedong issued a call that "we must also engage in artificial satellites."
"This call proclaimed the Chinese nation's confidence and courage to step onto the stage of space activities," recalled Pan Houren, then deputy head of the Dongfanghong-1 satellite overall design team.
In 1967, China named the first satellite Dongfanghong 1 and the first carrier rocket Long March 1. The Dongfanghong-1 satellite is a scientific exploration satellite with a 72-hedron shape similar to a sphere, a diameter of 1 meter, and a weight of 150 kg. It is scheduled to be launched around 1970. The mission of this satellite is to lay the foundation of technology and practice for the future development of various types of satellites for earth observation, communication and broadcasting, and weather forecasting.
On February 20, 1968, the China Academy of Space Technology was officially announced, and Qian Xuesen served as the dean.
Launching artificial earth satellites is a huge and complicated system engineering, involving many fields including research, production, launch, measurement and control. "It looks simple now, but there was a gap between the industrial level and technological level at that time." Sun Jiadong, who was instructed to lead the development of the satellite, described it.
With the continuous modification of the design scheme, the weight of the Dongfanghong-1 satellite has increased from the initial 150 kg to 173 kg, far exceeding the sum of the first four satellites in the world. It is hard to imagine the difficulty of sending such a heavy satellite into space. Qi Fake, one of the heads of Dongfanghong-1 satellite technology at the time, said that the satellite must also meet the four technical requirements put forward by the state, that is, "can get on, catch on, hear, and see."
In order to complete this arduous task, researchers have begun a difficult exploration of chasing their dreams.
Complete four goals
"Able to get up, hold, listen, and see", only 12 words summarized the overall technical plan and objectives of the Dongfanghong-1 satellite, as well as the technical difficulty.
The first consideration is whether it can "get up." According to the plan, the Dongfanghong-1 satellite will operate 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 a strong propulsion capability.
The experts proposed a "two-combination" plan: using medium and long-range missiles as the first and second stages, and using sounding rocket technology to develop the third stage. Through these three levels of continuous transmission, the satellite is sent into a predetermined orbit. Under the leadership of Ren Xinmin, who was the head of rocket technology at that time, the launch vehicle officially entered the development stage, and finally achieved the perfect combination of missile technology and sounding rocket technology, which solved the problem of "getting up" and also allowed the As long as the capability is, the stage of the aerospace is as big as it is. "
If you want to "catch" a satellite on the ground, you must always grasp the position of the satellite in space. This requires calculating the distance between the satellite and the ground. After comparing several schemes, the experts decided to use the Doppler principle-measure the speed according to the change of the radio wave frequency, and then measure the distance. This solution required a special equation, which was a problem for Chinese scientists at the time.
In response, the Dongfanghong-1 satellite developers changed their design ideas, reconstructed the satellite orbit measurement equation, and solved the mystery of the satellite orbit measurement equation, so that the position of the satellite in space can be monitored at any time.
Next, people focused on "hearing" and "visible".
It was very difficult for satellites to play the "Dongfanghong" music in space. The developers replaced the "keys" with 6 highly stable oscillators, and controlled the pronunciation with the beats produced by the program-controlled circuit. After hundreds of tests, they finally ensured that Dongfanghong No. 1 played "Dongfanghong".
Hu Qizheng, a member of the Dongfanghong-1 satellite general group, mentioned that to let ordinary radios receive music from satellites, everyone proposed a "relay" method. "We can't directly hear the music played by Dongfanghong No. 1 satellite on the ground, we need to send it through the satellite's antenna, receive it from the ground station, and then broadcast it on the radio." Qi Faxu recalled.
The last difficulty is "visible". To see the moons in space with the naked eye, its brightness must rise from the seventh to fourth. Not only that, because the diameter of the Dongfanghong-1 satellite is only 1 meter, it also makes "visible" more difficult. In the end, the developers found inspiration from the folding and opening characteristics of the folding umbrella, and decided to install an "observation body" made of high-reflectivity materials that can be stretched out in space on the third stage of the launch vehicle. Due to the huge size of this "observing body" and the extremely high reflective brightness, people can directly observe it.
Solve world problems
Set a new record
Another problem that cannot be avoided on the way to the sky is that satellites must withstand the test of extreme temperature changes in space.
In space, the temperature on the sunny side of the satellite can reach more than 100 degrees Celsius, and the temperature on the back side of the satellite can drop to minus 100 degrees Celsius. How to maintain the normal "body temperature" of the satellite 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 system needs a lot of power to operate normally, and the power carried by the satellite is very limited. In the end, the researchers came up with a zero-power-consumption solution for the temperature control system: using the heat generated by other instruments during work, to help the satellite control the temperature, and ingeniously solve the problem of large power consumption.
Overcoming various difficulties, the development of satellites and launch vehicles was successfully completed.
After a journey of 4 days and 4 nights, in February 1970, the Dongfanghong-1 satellite and the Long March-1 carrier rocket were transported to the Jiuquan Satellite Launch Center.
On the day of April 24, 1970, the launch entered a negative 8-hour countdown, and the sudden news that the "measurement and control signal was unstable" made the technicians on the scene nervous.
Where does the interfering signal come from? People locked the source of the problem at the connection between the satellite and the rocket. For the purpose of temperature control, there is an aluminum-plated film at the junction of the rocket and the satellite that wraps the instrument. Because it is not fixed properly, it shakes, resulting in unstable signals. After fixing, the problem was solved. At this time, the dark clouds in the sky also disappeared, and the sun shone on the body of the launch vehicle. The moment of soaring finally arrived.
The Dongfanghong-1 satellite, which has accurately entered the scheduled Earth orbit, has been in orbit for 24 days. Claim. As the weight of Dongfanghong-1 exceeded the total weight of the first satellites of the previous four countries, it also created a new record in the history of human spaceflight.
"By insisting on self-reliance and hard work, we have overcome the impossible, and finally successfully sent the Dongfanghong-1 satellite into space." Qi Faxu said.
The successful launch of the Dongfanghong-1 satellite was a major event that shook the world in the 20th century, and it proclaimed the rise of an oriental space power. The Dongfanghong-1 satellite, along with nuclear bombs and missiles, has been hailed as "two bombs and one star."