52 years later, Dongfanghong-1 is still flying in the sky? !

This article was reviewed by Liu Yan, Space Application Engineering and Technology Center, Chinese Academy of Sciences

Who would have thought that 52 years later, the Dongfanghong-1 satellite is still flying in the sky?!

To be honest, I wouldn't have believed it if someone hadn't really taken the photo.

Just a few days ago, a video of "the same frame of the century" made netizens collectively break down:

△Image source: Tencent Video

In the video, the "Dongfanghong-1" satellite passed by the Chinese space station, and the two artificial celestial bodies, which were launched nearly half a century apart, were "looking at each other from afar" in the night sky.

Some netizens lamented the miracle of these two "stars" reuniting after being separated by half a century:

But what surprised more netizens was that the "Dongfanghong-1" was still in the sky:

After all, the first artificial satellites launched by the United States, the Soviet Union and Japan at the same time all crashed due to various reasons such as orbit and power.

The significance of "Dongfanghong-1" itself needs no elaboration. It is my country's first artificial satellite. As the "one satellite" in the "two bombs and one satellite", it carries the dreams and original aspirations of generations of astronauts.

The launch of "Dongfanghong-1" marked the beginning of China's exploration of space.

After that, my country's aerospace development has been "prosperous" -

Sun Jiadong, the chief technical officer of the "Dongfanghong-1" satellite, became the first chief technical officer of my country's lunar exploration project, opening the way for my country's lunar exploration and deep space exploration;

Qi Faren, one of the technical leaders of the "Dongfanghong-1" satellite, served as the chief technical leader of the Shenzhou spacecraft, marking the beginning of my country's history in manned space flight.

Chen Fangyun, chief technical officer of the Dongfanghong-1 satellite tracking and control system, became one of the founders of the Beidou satellite navigation system;

…

But in fact, the "Dongfanghong-1" satellite, which has been flying in space for 52 years, was originally developed based on almost "nothing" from theory to industry.

With a funding of 200 million yuan, more than 5,000 people used pens and abacus to "manually" complete the entire process of satellite design, production, manufacturing and launch.

For the first time in the universe, there was a voice from China

In 1970, for the first time in the universe, there was a voice from China.

The successful launch of China's first artificial satellite, Dongfanghong-1, opened a new era in China's space history.

The satellite was named "Dongfanghong-1" because it sang the song "The East is Red" to the world in space.

It weighs 173 kilograms and is a spherical polyhedron with a diameter of 1 meter, equipped with four 3-meter-long whip antennas.

After the satellite was launched, its orbital period in the Earth's orbit was 114 minutes. While playing the song "The East is Red" at a frequency of 20.002 MHz, it transmitted telemetry parameters and scientific exploration data.

Today, China’s Space Day is celebrated every year on the day of launch - April 24th.

But looking back at the development of Dongfanghong-1 from 0 to 1, everything was so difficult.

In the late 1950s, China formally proposed to build an artificial satellite.

Prior to this, the Soviet Union had successfully launched the world's first artificial satellite, and the United States followed closely, sending Explorer 1 into space in 1958.

At that time, China was still far from having the conditions to launch satellites in terms of economy, talent, etc.

Even the satellite and rocket models exhibited to the public during the tenth anniversary celebration in 1959 were all hand-made by young scholars.

According to CCTV reports, these young people's knowledge of rockets and satellites at that time was not as good as that of today's middle school students.

Even if the model is made, there are still a lot of practical problems that cannot be solved, such as the difficulty in determining design parameters, poor testing conditions, and the lack of supply of required production and processing equipment...

Chinese scientists have thought about learning from the big brother, the Soviet Union, and even went to Moscow to conduct research, but were met with a cold reception.

And because of the limited national strength, they decided to lay the foundation first and focus on the research and development of rockets, high-altitude physical detection equipment and so on.

The successful launch of the Dongfeng-2 medium-range missile marked that China had basically acquired the ability to launch artificial satellites.

Under the leadership of Qian Xuesen, Zhao Jiuzhang and others, the development of the Dongfanghong-1 satellite was officially put on the agenda.

△Image source: Xinhuanet, Music Installation

They also set a higher starting point: China's first satellite should weigh around 100 kilograms.

At that time, the weight of the first Soviet satellite was 83.6 kg, and the weight of the first American satellite was only 8.2 kg. The heavier the satellite, the higher the requirements for rocket engines and various equipment.

But they finally got it done, and the actual weight was 173 kg.

It was not until February 20, 1968, when the China Academy of Space Technology was established, that the development of Dongfanghong-1 was officially put on the agenda.

Qian Xuesen served as the first president, the research team consisted of over 5,000 people, and the central government allocated 200 million RMB.

△ Qian Xuesen

According to Xinhua News Agency, Pan Houren, deputy head of the overall design team of the "Dongfanghong-1" satellite, recalled:

Two hundred million RMB was not easy to come by at that time.

Because apart from funding, the older generation of astronauts had almost nothing.

Many difficulties encountered during this period were solved using "local methods".

For example, riveting is an important process in satellite manufacturing. At that time, the satellite factory was converted from a scientific instrument factory and had never done this before, and there were no rivet guns or trusses to fix the workpieces.

The workers relied on a small hammer and used their bodies as trusses to hammer the rivets in one by one.

Under these conditions, they solved a number of process problems and then entered the stage of multiple environmental simulation tests.

Qi Faren, one of the technical leaders of the "Dongfanghong-1" satellite, once recalled that during the summer test, because the satellite factory did not have a low-temperature test laboratory, he wore a thick cotton jacket and went to the navy's cold storage to conduct the test.

△Image source: Yuzhou sings "The East is Red"

The conditions are a bit difficult, but technology is constantly iterating.

On the eve of the establishment of the institute in 1967, Dang Hongxin, a pioneer and academic leader in China's tribology discipline, and his team solved a key problem in satellite transmission.

They chose a copper-based conductive dry film and successfully solved the problem of difficult ultra-short wave antenna signal transmission at -100℃ to 100℃.

The reason why the Earth can receive the music signal from Dongfanghong-1 is inseparable from the contribution of Dang Hongxin's team.

△Video source: Yuzhou sings "The East is Red"

The signal problem has been solved, but the satellite itself still has to withstand the test of extreme temperature changes.

At that time, this was a problem recognized by the world.

To this end, Chinese scientists 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 amount of electricity carried by the satellite is very limited.

Finally, they thought of using the heat generated by other instruments when they are working to help the satellite control its temperature. The external material used is aluminum alloy that has been treated for temperature control, thus solving the problem of high power consumption.

Soon, after two or three years, they achieved the goal of the first artificial satellite.

On April 24, 1970, the Long March 1 carrier rocket carrying the Dongfanghong 1 satellite successfully entered the predetermined orbit, completing a detection mission that lasted more than 20 days, and stopped transmitting signals on May 14 of the same year.

China has thus become the fifth country in the world to independently develop and launch satellites.

It took China less than five years from the formal launch of the project to the successful launch of the satellite.

And to this day, Dongfanghong is still flying in space, overlooking the development of China's space industry. Most satellites of the same period have fallen into the atmosphere.

How exactly is this done?

Why is Dongfanghong-1 still in orbit?

We have to start with the entire technical plan at that time.

When the Dongfanghong-1 satellite was designed, its main mission was to conduct satellite technology tests and detect the ionosphere and atmospheric density.

Therefore, the orbit is designed to be a near-Earth elliptical orbit with a perigee of about 441 kilometers, an apogee of about 2368 kilometers, and an angle of 68.5 degrees with the Earth's equatorial plane.

We know that satellites do not need power to fly around the earth in space, but rely entirely on inertia. In theory, if there is no resistance, there will be no energy consumption and they will fly forever.

But in fact, space is not empty, especially in the Earth's low-Earth orbit, there are still trace amounts of gas. The closer to the Earth, the more gas molecules there are. This is why the space station currently has to actively raise its orbit every once in a while.

As we mentioned above, Dongfanghong-1 operates in an orbit with a perigee of 441 kilometers and an apogee of 2,368 kilometers.

For comparison, the International Space Station currently orbits at an altitude of 420 kilometers. Therefore, even the perigee of Dongfanghong-1 is higher than the orbit of the International Space Station. Therefore, the resistance encountered by Dongfanghong-1 in orbit is very small.

As for another more common fate - entering the atmosphere (between 100 km and 300 km) and burning and disintegrating, that will also take a long time.

According to the latest data, the Dongfanghong-1 satellite's latest perigee altitude is 428 kilometers and its apogee altitude is 2030 kilometers.

That is to say, after half a century of operation, the perigee of Dongfanghong-1 has only dropped by 13 kilometers.

However, it is not easy to launch a satellite into such a high orbit. Initially, the Dongfeng-4 missile, the theoretical basis of the "Long March 1", did not have the power to launch a satellite to an altitude of more than 400 kilometers.

Therefore, the "Long March 1" was greatly optimized based on the Dongfeng 4, including upgrading the rocket to three stages, etc., and finally successfully sent the Dongfanghong 1 to the designated orbit.

The success of this mission has also laid a solid foundation for the subsequent development of my country's aerospace technology.

China's half-century space journey

The launch of the "Dongfanghong-1" satellite has been completed, and China's space journey has just begun.

In the following 50 years, the scientists who initially participated in the "Dongfanghong-1" satellite project, with the aerospace technology they had explored, went deeper into more complex fields and completed one impossible task after another.

From manned space flight to lunar exploration and deep space exploration missions, we are moving forward step by step towards the sea of ​​stars.

Wang Xiji proposed the technical plan for the "Long March 1" carrier rocket to carry the Dongfanghong-1 satellite into space and organized its development. After the Dongfanghong-1 mission was completed, he once again took on the heavy responsibility of being the chief technical officer of my country's first "recoverable satellite."

In 1975, my country's first recoverable satellite was successfully launched and recovered, marking the first step in manned space flight.

After that, Chen Fangyun, the chief technical officer of the Dongfanghong-1 satellite tracking and control system, and his collaborators jointly proposed the "dual-star positioning system", which became an important theoretical basis for the Beidou satellite navigation system.

Qi Faren, one of the technical leaders of the "Dongfanghong-1" satellite, was appointed as the chief technical leader of the Shenzhou spacecraft. He conducted a total of four unmanned spacecraft tests and countless ground tests.

In 2000, two Beidou navigation experimental satellites were successfully launched, and China finally had an independent satellite navigation system.

In 2003, "Shenzhou V" carrying Yang Liwei successfully launched into space, marking China's first truly manned space flight mission.

Hu Shixiang, the "launch general" responsible for launching the "Dongfanghong-1" satellite, was also the deputy commander-in-chief of China's manned space program at the time. He witnessed the historical process of my country from the launch of its first satellite to the successful manned space flight.

In the same year, Sun Jiadong, chief technical director of "Dongfanghong-1", took over as chief technical director of China's lunar exploration project, further extending my country's space dream from low-Earth orbit.

In 2007, my country's first lunar exploration satellite "Chang'e-1" was launched into space, successfully entered the lunar orbit and flew around the moon, and my country officially entered the lunar exploration era.

In 2008, "Shenzhou VII" was launched into space and entered the planned orbit. Chinese astronauts carried out their first spacewalk and mastered the technology of extravehicular activities in space.

In 2017, Tiangong-2 completed rendezvous and docking with Tianzhou-1, marking an important step in the construction of China's space station. In 2020, the Chang'e-5 probe was launched and successfully returned with lunar samples. In the same year, the Beidou-3 global satellite navigation system was officially launched...

Just a few days ago, a video of the Dongfanghong-1 and the Chinese space station in the same frame went viral on the Internet.

It was taken by Zhu Jin, a researcher at the Beijing Planetarium and editor-in-chief of "Astronomy Enthusiast" magazine, and Wang Zhuoxiao, a Ph.D. in astrophysics from Tsinghua University. It uses telephoto tracking and wide-angle short exposure methods.

△Zhu Jin on the left and Wang Zhuoxiao on the right

This day happened to be April 24, the launch date of the Dongfanghong-1 satellite, and also Zhu Jin's birthday. Every year on this day, he would go to see if Dongfanghong-1 was passing by.

And two days ago, Zhu Jin happened to take a photo of the Chinese space station (Tiangong Space Station) and Dongfanghong-1 in the same frame.

In the photo, the trajectories of Dongfanghong-1 and the Chinese space station were frozen in the night sky together, which was also called the legendary "century frame" by netizens.

When talking about the progress and impact of my country's space exploration in recent years, Zhu Jin said with emotion:

In recent years, China's deep space exploration, lunar exploration and manned space flight have made considerable progress, which has also influenced some children to pay attention to the starry sky and then possibly to astronomy.

I look forward to my country’s aerospace technology developing better and better.

Source: Quantum Bit