Shulou(Shulou.com)11/24 Report--

Jujube Jun Note: in the last article (link), I introduced the history of Chinese satellite communications before 1998. In today's article, we will continue with the rest of the story.

In the last article on the five categories of █ satellites, we talked about the development of Dongfanghong from No. 1 to No. 3 and became a general satellite platform.

We also mentioned that since the 1990s, the development of domestic satellites has gradually accelerated, and began to take the road of industrialization, and some satellite operation companies with enterprise operation have been set up.

In fact, since then, our country's satellite development strategy has gradually become clear. In addition to communications satellites, the state has also set up development plans for several major satellite applications according to the main uses of satellites.

What exactly does the use of satellites include?

Generally speaking, the functions of satellites can be divided into the following categories: communication and broadcasting, earth observation, navigation and positioning, scientific experiments and signal relay.

The Dongfanghong 2 series and Dongfanghong 3 series (part) we mentioned earlier, as well as the Xin Nuo series and the Asia-Pacific series, are all communications and broadcasting satellites, which are mainly used for television and radio signal retransmission, as well as telephone, telegram, fax and data signal transmission.

In the past, some home users would install "small pots", that is, watching TV programs with the help of communications and radio satellites.

Satellite TV "small pot" observation of the earth, this scope of use is even wider. The remote sensing satellite we often talk about falls into this category. The so-called "remote sensing" is to detect and perceive from a long distance.

In addition to remote sensing, meteorological satellites, resource satellites, ocean satellites and environmental satellites also belong to the category of earth observation satellites. (sometimes, Earth observation satellites are also directly referred to as remote sensing satellites, which classify meteorological satellites as remote sensing satellites. )

Remote sensing satellite navigation and positioning, which we should be very familiar with. The famous GPS (USA), Galileo (Europe) and our country's Beidou all fall into this category, also known as GNSS (Global Navigation Satellite system).

(I have specifically introduced this before: what is the GNSS technology behind Beidou? )

Scientific experiment satellites, which I will not introduce much, are all specialized satellites for experiments in the field of science.

Another category of satellites that is easy to overlook is relay satellites.

Relay satellites, which specialize in relaying signals. As we all know, the earth is round and turning constantly. Sometimes when you engage in aerospace missions (such as landing on the moon, landing on Mars, launching missiles), there is the possibility that the signal will be blocked by the earth.

Relay satellite, is to relay the signal to maintain a smooth link.

Signal relay our country's relay satellite, called Tianchuan-1, can be said to be very appropriate.

Mr. Xiaozao has made a list of these types of satellites in China, and everyone can understand at a glance that the categories are very complete:

The classification series of Chinese civil satellites, as mentioned above, these important satellite programs, such as "Beidou" and "Heavenly chain", were planned in the late 1990s and implemented after 2000.

After years of accumulation, these satellite series have formed a huge scale and play a great role in the national economy and people's livelihood.

Satellite antenna █ Dongfanghong 4, let's go back to the Dongfanghong series.

In 1998, the new Commission of Science, Technology and Industry for National Defense was established. In order to enhance the market competitiveness of China's independent research and development of communication satellites, the satellite field began to step up the demonstration of a new generation of large geostationary orbit satellite public platform, that is, DFH-4 (hereinafter referred to as "Dongfanghong 4 platform").

Dongfanghong No. 4 (model) in October 2001, the state formally approved the establishment of the Dongfanghong platform. In January 2002, it entered the stage of preliminary sample development.

In May 2002, the development of the Sino-2 satellite was launched.

According to the plan, SinoSat 2 is the first star of the East 4 platform. The satellite has a design life of 15 years and is equipped with 22-channel Ku transponders, load weight 430Kg, whole satellite weight 5100Kg, whole satellite power 7.6KW.

Unfortunately, in October 2006, the launch of Sino II failed, and the solar panels and antennas were not successfully deployed.

Soon after, on May 14, 2007, China launched the Nigerian Communication Satellite 1 to Nigeria, which also adopted the East 4 platform.

The project in Nigeria is the first commercial satellite delivery project obtained by China Great Wall Industry Corporation through international open bidding in 2004, and it is also one of the 10 major projects signed by China to enter the international satellite market.

At first, the launch of Nigerian Communications Satellite 1 was successful and was delivered to the Nigerian Space Agency. Unexpectedly, half a year later, because of the failure of the solar panel, the power was exhausted and failed again.

Later, on October 30, 2008, China successfully launched the Venezuelan Communications Satellite 1 based on the East 4 platform. Sinuo 5 and 6, Zhongxing 10, Pakistan 1R and Nigeria 1R, which were successfully launched around 2010, are all based on the East 4 platform.

From the perspective of technical performance, the capability of the East 4 platform is still very strong and basically belongs to the international advanced level.

After the Dongfanghong 4 platform (model) Dong4 platform is stable, the Dongfanghong 4 enhanced platform is developed. East 3 also has two upgraded types: East 3A and East 3B. These platforms are the main public satellite platforms in China in the 2010s.

I would like to add that the industry of that period.

In 2008, some changes have taken place in the satellite communications industry.

This year, the domestic telecom industry was reorganized for the third time. After the completion of the restructuring, China Satcom's basic telecommunications business was merged into China Telecom, and other businesses were merged into China Aerospace Science and Technology Group.

In 2009, SinoSatcom was integrated into China Satcom.

After the change, SinoSat was renamed into the "China Star" series.

After that restructuring, China Satcom has only the second type of basic telecommunications business in the satellite transponder rental, sale business and other business license, can be regarded as a temporary departure from the telecommunications industry. By the time they return, it will be ten years later.

The last article mentioned Asia-Pacific satellites.

In the early days, Asia-Pacific satellites used foreign platforms, and then gradually adopted domestic platforms, using East 4 and East 4 enhanced platforms. As follows:

Asia-Pacific Satellite is an H-share listed company with China Aerospace Science and Technology as its shareholder. After China Satcom went public in 2019, Asia-Pacific Satellite is its controlling subsidiary. Therefore, Asia-Pacific satellites have also become those of China Satcom. This is later.

The main satellite of the Asia-Pacific Satellite (picture from the official website)

China Satcom's main satellite, █ Dongfanghong 5, was launched from China's Wenchang Space launch site at 19:23 on July 2, 2017, carrying the long March 5 remote-2 rocket (CZ-5 / Y2), which was launched from the Shishi-18 satellite.

This practice No. 18 is based on China's new generation of communications satellite platform-Dongfanghong 5 satellite platform (DFH-5, hereinafter referred to as "Dongfanghong 5 platform").

Dongfanghong 5 (model) then, like the previous Dong2, Dong3 and Dong4, the first star of Dongfanghong 5 also unfortunately failed.

When the rocket flew to 252 seconds, the flight condition was abnormal. When flying to 346 seconds, the liquid hydrogen and liquid oxygen engine malfunctioned, resulting in an instantaneous sharp drop in thrust, resulting in the rocket unable to reach the predetermined flight speed and altitude. In the end, the rocket II and the satellite crashed into the sea in the western Pacific Ocean, and the launch mission failed.

After some review and improvement, the long March 5 remote three rocket carrying Shishi 20 satellite was successfully launched 20:45 on December 27, 2019.

On January 5, 2020, after seven orbital maneuvers, the satellite was successfully located in a geosynchronous orbit at an altitude of 36000 km. This means that the East 5 platform was successfully launched for the first time.

East 5 platform can be said to be China's "Star of Hope". It has a launch weight of 10 tons, can carry 2 tons of payload, provides a payload power of 22 kilowatts, and has a design life of up to 16 years.

It adopts advanced technologies such as truss structure, high-power power supply and distribution system, advanced integrated electronics and high-thrust multi-mode electric propulsion. It has the characteristics of "high load bearing, high power, high heat consumption and high control precision", and its technical index is in the lead in the world.

In the next few years, the East 5 platform will be the main public satellite platform of our country and will participate in the market competition of international commercial satellites.

In the last ten years, an important direction of the development of satellite communications is the satellite Internet.

What on earth is satellite Internet? What is a high-throughput satellite? How did the satellite Internet develop? What is the pattern of satellite competition at home and abroad?

Let's take a look at the second part: "50 years of vicissitudes: the Development of Satellite Communications in China (part two)" (about the strongest popular science of satellite Internet)

References:

1. "Historical Review of the Development of Satellite Communication system in China", Wei Xuexing

2. "70 years 70 people" Communication | Min Shiquan: a star in the sky, decades on earth ", Min Shiquan

3. "White Paper on the Development of China's Satellite Communications Industry", Sadie think tank

4. "Satellite Communications bear witness to the normalization of diplomatic relations between China and the United States", people's Post and Telecommunications

5. History of the Development of China's Satellite Industry, Chen Yunli

6. "the opening of a New era of Satellite Communications in China", Wang Chunting

7. "the Development of Chinese Communication Satellite", bilibili, Wen Yao Xinghe

8. "the great journey of the development of China's satellite communications industry in the past 45 years", Guo Haoran, Zhang Yuwei, Guo Xinzhe and Yin Shuming

This article comes from the official account of Wechat: fresh Jujube classroom (ID:xzclasscom), author: Xiaozaojun

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