A big country of aerospace with black technology

In this era, the concept of satellite communication network is not very mature.

The common way of communication still relies on ground transmission towers and various cables for relay connections.

Although this method of communication also has the advantage of stable connection, but because of the need to build a huge number of ground base stations and communication cables, the required infrastructure investment is actually very large.

At this time, the most commonly used communication method for people in China was landline telephones, and very few people could use mobile phones.

So there is actually no demand for mobile communications.

However, there is no such demand now, which does not mean that there will be no such demand in the future.

Later, in China, in just 20 years, it became the country with the most mobile devices in the world, and the demand for this is actually very large.

Therefore, it is necessary to plan the construction of the low-orbit satellite communication network now for the sake of taking precautions.

Generally speaking, a distance of 100 kilometers to 300 kilometers from the earth's surface is a low orbit. The service life of satellites operating in these orbits is generally not very long, because they will continue to fall to the earth's surface under the influence of the earth's gravity. Constantly uses fuel to maintain orbital altitude.

Low orbit has many advantages for satellite communication, the biggest advantage of which is the reduced cost.

For example, the orbit altitude of Iridium is about 800 kilometers, while the altitude of the new generation of low-orbit communication satellites is basically about 300 kilometers.

This lowers the thrust requirements of the rocket, and greatly increases the number of satellites that can be launched at one time.

For example, the Changsan B rocket, which flew for the first time this year, has a carrying capacity of 5.65 tons to an 800-kilometer orbit, and 10.82 tons to a 300-kilometer orbit.

This means that the launch cost of a low-orbit satellite is half that of a high-orbit satellite.

Of course, no one in China except Zhang Xingyang is really aware of the commercial and military uses of the low-orbit communication network.

But this does not prevent Zhang Xingyang from instilling his ideas in others.

"Mr. Chen, what do you think the future form of network communication will be?"

This is a symposium on the eve of the establishment of the domestic Internet Network Information Center, discussing various issues of the future Internet.

Although Chen Zhongyan is the chief teacher of Beidou Navigation, it does not mean that he does not understand the development of the Internet, on the contrary he is very clear.

"The future network communication method must be connected to user equipment through wireless transmission. As for whether to use ground base stations for signal coverage or satellite networks for signal coverage, it is still difficult to say."

"Xiao Zhang, what do you think?"

The two people who came to this meeting were more of an observer role. After all, China has been preparing for the establishment of the Internet Information Center for several years, and the preparations for all aspects have actually been relatively complete.

So the two of them still like to chat a little bit more about their majors, the content of the aerospace field.

"Old Chen, these two methods actually have their own advantages, but I personally prefer to use the low-orbit satellite network method."

"Oh? Tell me your reason."

Chen Zhongyan became a little interested, because he felt that Zhang Xingyang really seemed to have his own unique insights.

"Now the only satellite communication network used in the world is the global telephone service that Iridium just launched within this year."

"But because the number of communication satellites they actually use is only 66, although they can cover the whole world, the amount of data that can be accessed by a single satellite at the same time is very low, and it is impossible to meet the huge amount of data after the advent of the Internet era."

"So if you want to truly connect to the Internet through satellites in the Internet era, what you can really use is to launch a large number of small satellites in the low orbit of the earth for network communication."

Chen Zhongyan didn't expect Zhang Xingyang's ambition to be so big, because if this method is really used for network construction, the construction cost required will definitely be much higher than that of using ground base stations for networking.

"Xiao Zhang, have you ever thought about such a cost issue and the follow-up maintenance issue?"

Chen Zhongyan frowned, and expressed his opinion, not particularly agreeing with Zhang Xingyang's thoughts.

"Old Chen, the cost is actually not as high as you imagined."

"Huh? Here, the cost of launching the rocket alone is a lot, not to mention the cost of the satellite."

As the chief engineer of the Beidou navigation system, Chen Zhongyan is naturally no layman. He knows that the cost problem here is mainly concentrated on satellites and rockets.

However, he didn't know that the Rocket Research Institute has been busy with the research process of new rocket engines and new recoverable rockets this year, otherwise he would not have such concerns.

"Don't worry about this. Our research institute is currently developing a high-thrust liquid oxygen kerosene engine, which can meet the requirements of multiple recycling."

"If recyclable rockets are used, the cost of launching satellites will be reduced to a very low level. It is estimated that the launch weight of one kilogram will not exceed 5,000 yuan."

"As for the problem of satellites, we don't need to use one generation of satellites like Iridium for more than ten years, which actually makes his satellites costly and difficult to replace."

"The designed service life of the satellite only takes one to two years, which not only reduces the production cost of the satellite, but also makes it more convenient for future upgrades."

Chen Zhongyan thought in his heart, if what Zhang Xingyang said was true, then the low-orbit satellite network could still be tried.

I just don't know if what he said is true. After all, Zhang Xingyang is too young. According to ordinary people's thinking, he can't do things well without talking.

Although Zhang Xingyang has done a lot of things since he took over the research institute, he still hasn't accumulated enough prestige to make people believe in him.

"Mr. Chen, let me do the math for you. The initial construction of the domestic satellite communication network will require the launch of about 4,000 low-orbit satellites."

"The new generation of recyclable rockets we designed can launch a load of about 26 tons to an orbit of 300 kilometers at a time. Assuming that each satellite weighs 250 kilograms, then 104 satellites can be launched into the sky at a time."

"Calculated in this way, 4,000 satellites only need 40 rocket launches to complete."

"If reusable rockets are used, even if each rocket is reused only five times, then only eight rockets are needed to complete the entire launch mission."

"Even if only one stage of the rocket can be recycled, it can save a lot of money, and our rocket uses liquid oxygen kerosene as fuel, which is cheap."

"Comprehensively calculated in this way, the cost of building a low-orbit satellite network is actually much cheaper than building thousands of ground base stations."

Zhang Xingyang carefully calculated the cost for Chen Zhongyan.

At this time, Chen Zhongyan realized that he seemed to be really convinced by him, and laughed:

"Xiao Zhang, what you said is very good, but when will your rocket be built?"

"It is impossible for the country to have so much time to wait for you!"

"Although I really hope that this system can be established, in the short term, the technical difficulties are still quite large."

Technical issues are the least of Zhang Xingyang's considerations. What he needs is more policy support and funds.

"Old Chen, our rocket will definitely be tested within the next year, and the country will never be allowed to wait for us!"

Looking at Zhang Xingyang, who was about to issue a military order, Chen Zhongyan was also a little curious about how far he could go:

"Okay, I will talk to my superiors about my ideas in this regard, but if you want to really realize this, it still depends on the progress of your rocket research and development."