CCTV News:The geostationary communication satellite represents the development level of a country’s satellite communication. It is an important resource that constitutes the foundation of the information superhighway and an important embodiment of a country’s comprehensive strength and technical level.
People who often travel in China know that mobile phones and notebooks can’t get on the Internet on flying planes and ocean-going ships. Similarly, on high-speed high-speed trains, mobile phone signals are intermittent. However, with the development of a new generation of communication satellites in China, full coverage of online chatting, ocean-going video entertainment and remote mountain signals will become a reality.
China’s independent research and development technology breaks the monopoly of foreign air communication
Maritime video will no longer be a dream.
On April 12, 2017, China successfully launched the Shijian-13 satellite in xichang satellite launch center using the long march 3b. After completing the on-orbit test, the satellite was named Zhongxing-16.This is the first Qualcomm communication satellite in China, with a total communication capacity of over 20G, which truly realizes the broadband application of autonomous communication satellites.
Zhang Wei, Senior Engineer of the Fifth Academy of Aerospace Science and Technology Group:The development of Qualcomm measurement technology represents that we are now on the ground, and you can use our satellite to realize video. Originally, only one voice communication function can be realized. Now we can video, so there is still a great application direction, that is, our aircraft. This is the first time that China has used Ka-band broadband communication technology on communication satellites.
Satellite capacity is actually like a highway. The original C-band and Ku-band capacity of communication satellites can only accommodate two cars at the same time, and the cargo they can carry, that is, information and data, is limited. However, the capacity of Ka-band satellite is much larger, it can drive 10 or more cars on the road at the same time, and the amount of information and data it can carry far exceeds that of other frequency bands.The breakthrough of this technology means that broadband internet access can be realized anytime and anywhere through communication satellites in the future, especially in areas that cannot be covered by ground communication networks, as well as on aircraft, high-speed rail, ships and other means of transportation.
Zhang Wei:Now everyone on the plane knows that communication can’t be realized. After the technology of HTS (Qualcomm Communication Satellite) is popularized in the future, we can also realize our communication on the plane based on satellites, including high-speed rail, ships and so on. HTS is a very popular application direction.
Zhang Wei told reporters that relying on Qualcomm’s satellite communication technology, a satellite broadband communication network will be built in the future. By then, no matter whether you are in an airplane at an altitude of 10,000 meters, a high-speed high-speed train, or a ship in the vast sea, or a deserted desert, deep mountain or island, you can browse the network and make video calls at high speed.
At present, the Fifth Academy of Aerospace Science and Technology Group has developed satellite mobile communication terminal products for outdoor, high-speed rail, ships and other aspects based on the Qualcomm satellite of Zhongxing 16. The original satellite communication terminals, limited by satellite design, are relatively large in size, and are generally installed on buildings or large vehicles.Now, relying on Qualcomm satellite, the terminal receiving device of communication satellite can be miniaturized, and ordinary household SUV can be installed.Zhang Ge, a senior engineer of the Fifth Academy of Aerospace Science and Technology Group, demonstrated a portable satellite broadband communication system for reporters. This system has the function of one key to the satellite, and can quickly connect the network when the ground communication network is damaged or interrupted in the earthquake-stricken area.
In addition to this portable satellite broadband communication system, the team led by Zhang Ge is still developing satellite broadband communication systems for high-speed trains and ocean-going ships.
Zhang Ge, Senior Engineer of the Fifth Academy of Aerospace Science and Technology Group:At present, our equipment supports more than 500 people, that is, if you install such a device on a luxury oil tanker, all the people on board can access the Internet directly via satellite by taking your ordinary mobile phone and connecting to the ship’s WIFI.
Combining technical test with demonstration application, Zhongxing-16 carried out high-speed laser communication test on the geosynchronous orbit satellite for the first time, with the highest speed of 2.4 G.. Satellite laser communication has the advantages of large communication capacity, long transmission distance and good confidentiality. If the test is successful, it marks that China has reached the international advanced level in this field.
On August 6th, 2016, China successfully launched Tiantong-1 satellite 01 in xichang satellite launch center, which is the first star of China satellite mobile communication system, also known as the "China version of maritime satellite", and its successful launch marks that China has entered the "mobile phone era" of satellite mobile communication.
After the Wenchuan earthquake in 2008, the ground communication network in the earthquake zone was completely paralyzed. At that time, China did not have its own mobile communication satellite system, so it could only rent foreign satellite phones for earthquake relief. The international mobile satellite system has formed a number of global or regional mobile communication systems, which are not only widely used in personal communication, ocean transportation, offshore fishing, air passenger transport and other fields, but also can realize barrier-free communication and determine the location in the case of natural disasters such as earthquake, flood and frost. After the Wenchuan earthquake, Tiantong No.1 was established.
The reporter learned that the technical indicators and capabilities of Tiantong-1 satellite have reached the level of international mainstream mobile communication satellites, and it has completely independent intellectual property rights. In particular, Tiantong-1 satellite has solved the technical problem of deploying an oversized antenna, making the satellite telephone terminal used on the ground more miniaturized and mobile.
The selfless dedication of several generations of researchers has been passed down from generation to generation.
Make China’s satellite industry from scratch. From lagging behind to leading
In recent years, our communication satellites have been successfully launched and put into use, covering the cutting-edge technologies and applications in the development of communication satellites, such as broadcast and television live broadcast, Qualcomm broadband satellite, mobile communication satellite and data relay satellite. Looking back, when we started to develop satellites, we were not only poor. Moreover, the foundation is weak. Under such conditions, our researchers insisted on self-reliance and selfless dedication, and finally embarked on a road of research and development of China communication satellites. Although this road was not smooth, it also experienced setbacks and hardships.
In the exhibition hall of the Fifth Academy of China Aerospace Science and Technology Group, real products from Dongfanghong-1 to Dongfanghong-4 satellites are displayed, which have witnessed the development of communication satellites in China.
Dongfanghong-1 was China’s first artificial earth satellite developed by the older generation of space scientists and technicians through self-reliance under the conditions of poverty and weak economic and technological foundation at that time. Due to the limitation of technical level at that time, it did not have communication function.
Zhang Wei, Senior Engineer of the Fifth Academy of Aerospace Science and Technology Group:After the success of this satellite, it actually created a precedent for our country’s artificial earth satellite, but its significance only reflects from scratch, so our satellite will be put into use after all.
After the successful launch of Dongfanghong-1, in order to make the communication satellite truly practical, the older generation of space science and technology personnel, represented by Sun Jiadong and Qi Faren, established the belief of "developing China people’s own communication satellite on their own". After nine years of hard work, Dongfanghong-2 communication satellite was finally developed successfully. On April 8, 1984, Dongfanghong-2 experimental communication satellite was successfully launched, making China the fifth country in the world to independently develop and launch geostationary orbit satellites.
Constrained by the technical level of electronic component development and material science research at that time, Dongfanghong-2 satellite had a small load and a short service life. The C-band transponder of the satellite had only two channels, while the C-slope transponder of the international advanced communication satellite had reached 24 channels at that time, and its service life was as long as ten years.
Zhang Wei:At that time, the power it could provide was very small, because there were so many solar cells, so it could provide so much power. Therefore, at that time, the on-orbit life of our country’s communication satellites was relatively short, that is, five years, and the effective power it could provide was very low, so the so-called transponder number was just a few transponders.
The main load of communication satellite is transponder, and one transponder can transmit more than ten sets of standard definition TV programs. The greater the load of communication satellite, the more transponders, which means that more radio and TV programs can be transmitted and more communication capacity can be provided. Zhang Wei told reporters that because Dongfanghong No.2 could not meet the needs of customers at that time, there was also a debate about "buying stars" or "making stars" in China. Under the circumstances at that time, astronauts had no choice but to develop Dongfanghong-3 satellite according to the international level at that time under the condition of weak technical foundation and poor facilities.
Zhang Wei:Dongfanghong-2 is a spin-stabilized satellite. By Dongfanghong-3, we have a three-axis stabilized satellite. With the adoption of the solar wing, the technology has a great leap forward, and we can only inherit about 20% of the technical foundation of Dongfanghong-2, and the remaining 80% is based on the independent innovation of our astronauts in China.
From the national project in 1986 to the successful launch of Dongfanghong-3 satellite in 1997, researchers have solved hundreds of technical difficulties in 11 years, gnawed down more than ten "hard bones" and experienced the pain of the first satellite launch failure. Dongfanghong-3 satellite not only achieved a leap in the development technology of communication satellites in China, but also provided a highly reliable communication satellite platform for China’s space industry.
In 2000, Dongfanghong-4, aiming at the international first-class level, began to be developed. The design life of the satellite platform was increased to 15 years, and the number of transponders carried was increased to 52. At that time, the market goal of Dongfanghong-4 communication satellite was not only to occupy the domestic market, but also to go out and seize the international market.
While researching and developing the communication satellite platform of Dongfanghong-4, they are also exploring the market of Dongfanghong-4. In May 2002, they signed a purchase order contract for Xinnuo-2 satellite with Xinnuo Satellite Communication Co., Ltd.; In May, 2004, he participated in the bidding for the whole satellite development and launch project of Nigeria Communication No.1 satellite, and stood out from 21 companies including the United States, France and Britain, and won the bid successfully.
Zhang Wei:Dongfanghong-4 satellite, its weight reached 5 to 5.5 tons, and its load capacity reached about 600 kilograms. This level was actually at the same level as the international advanced level at that time, so through Dongfanghong-4, we actually realized a transformation process from following to running together.
In 2010, focusing on the demand of high-power communication satellites in the next 20 years, a new generation of Dongfanghong-5 satellite with high load, high power, long life and expandability began to be developed. At the same time, the Fifth Academy of Aerospace Science and Technology Group is also tracking the most advanced technology in the world and expanding the technical level of the original satellite platform. In order to improve the payload of communication satellites, they have to make the electronic system smaller and smaller.
Gong Jianglei, deputy director designer of the Fifth Academy of Aerospace Science and Technology Group: These products are actually a hardware product based on the integrated electronic system on our entire communication satellite.Now these four products have actually replaced more than 20 previous products. The previous products were relatively large in quantity and volume, and we have reduced them by about 50%, which is also a relatively leading level in the whole world.
It is an inevitable choice for the Fifth Academy of Aerospace Science and Technology Group to follow the world’s leading technology and achieve technological transcendence in some technical fields. After graduating from Ph.D. in 2008, Chen Yue came to the Fifth Academy of Aerospace Science and Technology Group to be responsible for the control and promotion of communication satellites. Just after working for more than two years, he proposed to the institute the research on electromagnetic propulsion of communication satellites without working medium, which was still controversial at that time.
Chen Yue, deputy director designer of the Fifth Academy of Aerospace Science and Technology Group:Everyone’s main doubt is that this technology may be scientifically researched and developed in engineering before it is fully explained. Is it risky or is there a principled error? This is the main controversy.
Communication satellites in space need to adjust their attitude and maintain their orbits, so satellites will carry a lot of propellant. The traditional chemical propulsion method is to generate thrust by propellant oxidation. At present, the electric propulsion method used in satellites is to ionize the carried working medium gas, and then spray the plasma to generate thrust. Both of these propulsion methods need to carry working medium, that is, propellant and gas.
Chen Yue:Figuratively speaking, these liquids or gases stored in the tank, once these working fluids are used up, the engine can no longer be used, and its life is up. And our current propulsion mode, this electromagnetic propulsion, is that as long as there is electricity, as long as the equipment can work normally, it can work and generate thrust.
There is no technology and experience to learn from, and there is no reference to any foreign materials. This technology is in the initial stage of technical experiment at home and abroad, and Chen Yue and his team are facing great challenges.
In order to encourage young people to innovate, the Fifth Academy of Aerospace Science and Technology Group set up a special fund for R&D and a special fund for doctoral growth to give financial support. Moreover, the core R&D personnel were not assessed for three years, and they were given strong support in personnel and experimental equipment to ensure that they concentrated on technical research.
Chen Yue:Through the independent research and development fund of the Science and Technology Committee of our institute and the independent research and development fund in our institute, we can support us, so that we can focus on this matter without worrying about the guarantee of conditions. It can be said that this is like an incubation. If there were no such incubation conditions at the beginning, we would not have this progress.
The reporter learned that at present, many key technologies of Dongfanghong-5 satellite platform, which represents that China’s communication satellites have reached the international leading level, have made major breakthroughs and need to be verified in orbit. Dongfanghong-5 platform has a total satellite power of 30,000 watts, a payload of more than 2,000 kilograms, and 120 transponder circuits, and some technical indicators exceed the level of developed countries. Most of the products on Dongfanghong-5 platform can be truly localized, independently controllable and no longer dependent on imports.
Half-hour observation: Aerospace, China’s brightest "business card"
From the first Dongfanghong-1 satellite to the world-leading Dongfanghong-5 satellite, the development of China’s communication satellites has gone from scratch, from following to running in parallel.
The development level of communication satellites represents a country’s scientific and technological level in the field of space science and technology, and it is also an important embodiment of a country’s comprehensive strength. Although we have experienced failures and setbacks in the development of communication satellites, we have finally been at the forefront of international communication satellites in just a few decades.
This is the result of the silent and selfless dedication of the vast number of aerospace science and technology workers, and it is also a continuation of the spirit of the older generation of astronauts.
Source of this article: CCTV Finance "Economic Half-hour"