China News Service, Beijing, May 10th (Ma Shuisha and Dong Jiaying) On May 10th, the Long March 7 Yao-5 carrier rocket carrying the Tianzhou-4 cargo spacecraft ignited and took off at the Wenchang Space Launch Site in China, and the space station will be fully completed in 2022. The first flight mission was a complete success.
The Long March 7 carrier rocket was developed by the First Academy of China Aerospace Science and Technology Corporation.
Shao Yetao, the chief designer of the Long March 7 carrier rocket, said that this is the fourth time that the Long March 7 carrier rocket and the Tianzhou cargo spacecraft have gone to space together. , the overall technical state of the rocket has also gradually stabilized, and the flight reliability assessment value has reached the international advanced level of 0.9838.
The Long March 7 Yao-5 carrier rocket carrying the Tianzhou-4 cargo spacecraft ignited and took off at China's Wenchang Space Launch Site.
Photo by Tu Haichao
Full of power: fuel weight accounts for more than 90%
The supplies that astronauts need to eat, wear, use and even breathe in space, and the fuel needed to maintain the correct orbit of the space station, all need to be delivered by cargo spacecraft in time.
In order to send a cargo spaceship carrying a large amount of materials into space on time, it is necessary to have a carrier rocket with sufficient capacity, "power" and high reliability.
The Long March 7 carrier rocket has a low-Earth orbit carrying capacity of 13.5 tons, which is more than half of that of conventional fuel carrier rockets.
A rocket is a "special car" that carries loads such as satellites to space. For this "special car", the smaller the dead weight, the better, and the more fuel that can provide power, the better.
Because of this, as much "traffic" as possible can be reserved for "passengers".
The Long March 7 carrier rocket is a big man with "steel iron bones", with a total weight of more than 500 tons, but 90% or more of it is the weight of fuel. The weight of the rocket shell, cables, instruments, etc. together is only more than 50 tons.
Xu Lijie, a rocket design expert from the General Department of the First Academy of Sciences, pointed out that the larger the proportion of fuel in the overall weight of the rocket, the higher the structural efficiency of the rocket, indicating that the design is more reasonable.
The weight of the rocket's shell, cables, instruments, etc. is called "dead weight", and these components should be designed as simple and powerful as possible to reduce weight.
The Long March 7 Yao-5 carrier rocket carrying the Tianzhou-4 cargo spacecraft.
Photo by Tu Haichao
Low temperature fuel: Safe parking for 24 hours
According to Zhu Pingping, a rocket design expert from the General Department of the First Academy of Sciences, the new-generation launch vehicles represented by "Chang 5" and "Chang VII" are filled with liquid hydrogen, liquid oxygen and liquid oxygen, kerosene, liquid hydrogen and liquid hydrogen. After the liquid oxygen is burned, water is produced, which is non-toxic and pollution-free, and greatly improves the carrying capacity of the rocket.
As a low-temperature fuel, the temperature of liquid hydrogen reaches minus 253 degrees Celsius, and the temperature of liquid oxygen reaches minus 183 degrees Celsius.
After the low-temperature fuel is filled, the launch tower at the test site is like a "big cold storage". The partitions of the storage tank are covered with thick frost. Every time the test team goes to check, a thick layer of frost will form on the hair and eyebrows. .
Deng Xinyu, chief commander of the Long March 7 launch vehicle power system, said that the low temperature fuel is not only extremely low in temperature, but also flammable, explosive and easy to evaporate, and the parked rocket is like a "bomb".
At present, the Long March 7 carrier rocket can be parked for up to 24 hours after refueling.
It is understood that at the beginning of the development of the rocket, the researchers included the 24-hour parking after refueling as a design standard into the model development process, so as to gain more favorable time for the successful launch.
Tianzhou "Special Train": Building a "Sky-Earth Transportation Corridor"
The Long March 7 carrier rocket is a new generation of medium-sized carrier rockets developed to meet the requirements of China's space station project to launch cargo spacecraft.
Cargo spacecraft, as messengers to deliver goods and propellants to space stations and space science laboratories, are affectionately called "exclusive trains" in space.
Last year, the Long March 7 launch vehicle sent the Tianzhou-2 and Tianzhou-3 cargo spacecraft into space respectively.
The re-entry into space with Tianzhou-4 this time is the first launch mission of the manned spaceflight project this year, and it is also the first mission of the space station construction stage, which is of great significance.
As a medium-sized rocket of a new generation of launch vehicles, the Long March 7 carrier rocket can not only meet the mission requirements of building a "transportation corridor between heaven and earth" for China's manned space station, but it will also undertake various types of launch missions in China's aerospace industry in the future.
The carrying capacity of the Long March 7 rocket can meet the requirements of most mainstream satellites. It faces the mainstream satellite market and has a wider adaptability. It is the "main force" of China's future space launch missions, and will become the "successor" of the main rocket in service in the future. It shoulders the important task of technological advancement and upgrading of the Long March rocket.
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