Long March 7, go!
Produced by: Popular Science China
Production: Long March 9 Team Yao Zhikai
Producer: computer network information center
The Long March 7 came into being: the fuel is more environmentally friendly and the carrying capacity is stronger.
With the continuous development of China’s space industry, the demand for the construction of space stations and the launch of high-quality satellites began to appear, but the older generation of launch vehicles could not meet the demand. In order to carry these massive cabins and satellites, it is necessary to develop a new type of large-capacity rocket. Moreover, the older generation of Long March rockets used a lot of highly toxic hydrazine-nitrogen tetroxide fuel. From the point of view of protecting the natural environment and working environment, it is also necessary to develop a new type of environmentally friendly launch vehicle.
In order to meet the power demand of new launch vehicles, new rocket engines are essential.
Thus, in 2001, YF-100 liquid oxygen/kerosene engine with 120 tons thrust and YF-77 liquid oxygen/liquid hydrogen engine with 70 tons thrust were approved. The Long March 5, powered by these two engines, also entered the public eye in 2006.
Two years later, in order to meet the launch demand of small satellites, Long March 6 was also launched in 2008. Its core stage used a single YF-100 engine, and its secondary stage used a single YF-115 liquid oxygen/kerosene engine with 18 tons of thrust.
The largest LEO (low Earth orbit carrying capacity) of Long March 5 is 25 tons, and the smallest LEO is 10 tons, while the SSO (sun synchronous orbit carrying capacity) of Long March 6 is 0.5 tons, and LEO is about 1 ton.
In order to fill the gap between Long March 5 and Long March 6, and to provide vehicles for future cargo ships, Long March 7 was put forward in 2010. In fact, the Long March 7 is almost a replica of the Long March 2-the 3.35-meter diameter core stage and the 2.25-meter diameter booster stage, which inherited the configuration of the Long March 2, but at the same time combined with the new rocket engine, which is really innovative.
The first stage of Long March 7 core adopts double YF-100 liquid oxygen kerosene engine, the four booster stages adopt single YF-100 liquid oxygen kerosene engine, and the second stage adopts four YF-115 engines. The successful test launch of Long March 6 last year has already declared that these two engines are very successful products. Therefore, the successful launch of the Long March 7 can be said to be fully guaranteed.
What is the main purpose of the Long March 7? Transport the ship!
The main purpose of the Long March 7 in the future is to carry the "Tianzhou" series of cargo spacecraft and give them to the astronauts in the space station. At the same time, the successful operation of the upper stage of Expedition 1 last year, the appearance of the upper stage of Expedition 2 this year and the possible new low-temperature upper stage in the future can also give more functions to Long March 7-it will help the satellite to go into geosynchronous orbit (GTO), so that Long March 7 has enough ability to replace some existing launch vehicles.
Besides Wenchang Chicken, Wenchang also has a satellite launch center.
The successful launch of the Long March 7 also announced the official opening of Wenchang Satellite Launch Center.
Why should the new launch center be located in Wenchang? Of course, Wenchang has many advantages:
As we all know, the lower the latitude, the faster the linear speed of the earth’s rotation, which can make the rocket carry more loads. The latitude of Wenchang Satellite Launch Center is only 19, which is a very favorable position.
2. Because the first-class diameter of the core of Long March 5 has reached 5 meters, it means that it can’t be transported by land-because it can’t cross the tunnel; Not by air-planes can’t transport things with such a large diameter. Therefore, shipping has become the only feasible way. The rocket body made in Tianjin can easily reach Wenchang by water.
3. The launching direction of rockets is basically east and south. This means that the burned remains of the booster and first-stage rockets will fall to the east and south. The east and south of Wenchang are near the sea, which means that the debris of the rocket will fall directly on the sea surface, which fundamentally avoids the risk of debris hitting people.
Many foreign space centers also refer to these elements. The Kennedy Space Center in the United States is the Atlantic Ocean to the east, with a latitude of about 28; The Kulu Space Center of ESA is also near the sea, and its latitude is only 4, which is close to the equator. It’s really enviable …
When the photos of the Long March 7 joint training were released last year, many people noticed the transformation of the launcher-the huge launch tower in the past was replaced by a simple launcher. In the launch of Long March 6 last year, this technology was also adopted, and even further-transshipment was directly carried out by the launch vehicle.
In the previous launch preparation process, our rocket had to be transported vertically from the assembly center to the launch tower, with almost no support. Because the rocket is very high, its center of gravity is also very high. When the wind is too strong, the transshipment work is quite dangerous. This is also unfavorable for rocket launch preparation.
In the past, the launch tower served as a rocket assembly room, so it was made so big. However, with the increase of rocket launch frequency, the launch preparation time is gradually shortened, and vertical transshipment can meet this requirement. With the development of technology, the current launch tower has only the functions of fixing and fuel filling, which can be done very lightly, making it possible to transport the arrow with the frame, thus reducing the requirements for the environmental conditions of transshipment. Of course, because the launch tower can’t be abandoned easily, and the transfer track from the assembly plant to the launch tower is fixed, the rockets in the other three launch centers can’t enjoy this treatment.
Playing a rocket is also a relatively expensive thing. I’m sorry if I don’t take this opportunity to bring a little load. Last year’s launch of Changliu carried 20 satellites at once, all of which were in orbit and successfully monitored and controlled. The Long March 7 is no exception. It brought a heavyweight passenger-a small-scale model of a new manned spacecraft.
The Shenzhou manned spacecraft now in use in China is well known to all. It draws lessons from the structure of the orbital module, return module and propulsion module of the former Soviet Union Soyuz spacecraft, so it also designed three cabins.
The new manned spacecraft, except the orbital module, consists only of the command module and the propulsion module, which is closer to some American spacecraft.
So why remove the orbital module?
From the development of spacecraft, the orbital module is a multifunctional module, which is essentially a stopgap measure without a space station. Astronauts can carry out activities in the orbital module and also carry out some experiments. Moreover, China’s Shenzhou orbital module can still operate in orbit for a period of time, providing more abundant data. In particular, on Shenzhou VII, the orbital module was also transformed into an airlock module by magic, which became a transitional module for spacecraft/space environment.
However, with the proposal of the space station plan and the successful operation of the "Tiangong" series of orbiters, astronauts have been able to have a more comfortable working and activity environment, and the orbital module has gradually lost its significance. When we remove the orbital module, the return module and the propulsion module can be made bigger, thus carrying more passengers and more fuel. It will lay a solid foundation for further manned space work (even manned moon landing) in the future.
Words written outside the article: two different sizes of propulsion modules really seem to be preparing for manned landing on the moon.
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