Why are our country’s satellite launches all in Jiuquan and not elsewhere?

As we all know, China has four space launch centers, namely Jiuquan in Gansu, Xichang in Sichuan, Taiyuan in Shanxi, and Wenchang in Hainan. Every year we can see news on TV about rocket launches from these space launch bases, but when launching manned spacecraft, we can only see the Jiuquan Satellite Launch Center.

In fact, so far, all manned spacecraft in China have been launched in Jiuquan (it may be launched in Wenchang in the future, and when will people land on the moon in the future). Why? Why not launch manned spacecraft from other bases?

The reason is not complicated either. The reason why Jiuquan was chosen was to consider the safety of the manned spacecraft’s normal landing. "The landing site of a manned spacecraft should usually be chosen in a vast, flat, inaccessible place. This can not only prevent the return capsule from being damaged by hitting special terrain during landing, but also ensure the safety of the astronauts and prevent the return capsule from hitting people during landing. .

Siziwang Banner, the current main landing site for my country’s manned spacecraft, can meet all conditions. "

So, what does the choice of landing site have to do with the launch site?

"There is an angle between the flight orbit of the spacecraft in space and the Earth's equator. This angle is called the orbital inclination. This inclination depends on the mission needs. Because changing the orbital inclination requires a lot of fuel, so from The orbital inclination from launch to return will not change much.

The time it takes for a spacecraft to orbit the Earth is much shorter than the time it takes for the Earth to rotate. At the same inclination, each circle will pass through a different place. . Based on these characteristics of the orbit, if launched from the Jiuquan Satellite Launch Center, the spacecraft will land at an ideal landing site after several flights. "

In addition, the launch site and landing site are selected for the manned spacecraft. Just like choosing a subway station. Not only are the stations special, but the "distance" is also relatively fixed. However, when choosing Jiuquan as the "starting station" for the manned spacecraft, we must consider not only the "terminal station" but also the "temporary station". This "temporary station" is the landing point for the spacecraft to escape.

Generally, the most likely time for launch failures is during the take-off period, so taking the launch pad as the origin and extending a sector in the launch direction, there should be no buildings and people to facilitate the escape of astronauts. The landing point for a spacecraft's escape is more important than the landing point for its normal return. China's manned rockets are generally launched in the east-west direction. Taiyuan and Xichang are areas with dense population and complex terrain. Wenchang currently does not have the ability to launch manned spacecraft. The landscape in the southeastern part of the Jiuquan Satellite Launch Center is dominated by desert and Gobi, making it the best choice for landing. "

The designers selected the "departure station" of the Chang'e F rocket based on the "final station" and "temporary station". Are the conditions of the rocket allowed?

In general, Rockets like dry weather. The Jiuquan Satellite Launch Center is dry and has little rain. It is sunny most of the year. The hot, humid and rainy climate of the Xichang Satellite Launch Center poses a threat to the electrical insulation of our country's rockets. It has been able to cope with the test of humidity and heat, but to ensure that it is foolproof, it is necessary to choose a launch site with better climate conditions. "

Finally, when choosing a launch site for manned spacecraft, you must consider infrastructure and history. conditions and other factors. Through overall planning and consideration, China's first satellite launch center, Jiuquan Satellite Launch Center, became the place where the "magic arrow" flies.