Chinanews.com, Beijing, December 22. Question: What is the high-altitude wind affecting the launch of the rocket?
Author Guo Chaokai Gao Chongrui
On December 22, the Long March 8 carrier rocket successfully flew for the first time at the Wenchang Space Launch Site in China, marking a successful conclusion to the launch of the new generation carrier rocket during the 13th Five-Year Plan period.
The Long March 8 rocket was originally scheduled to launch on December 20, but the abnormal high-altitude wind delayed the launch time by 2 days.
What is high-altitude wind?
How does a rocket launch respond to high-altitude wind?
The reporter interviewed space experts to find out.
At 12:37 on December 22, Beijing time, the Long March 8 carrier rocket was successfully launched at the Wenchang Space Launch Site in China, sending five satellites into the predetermined orbit with "one arrow and five stars".
Photo by Wanke
(1) What is high-altitude wind?
Rocket launch is a high-risk and complex system project, which is extremely susceptible to various factors. Even weather factors such as lightning, temperature, and wind will affect rocket launch.
Among many weather factors, high-altitude wind has the most prominent impact on launch.
High-altitude wind is generally 4 to 20 kilometers above the ground.
Pan Hao, the chief designer of the Long March 8 rocket control system of the China Academy of Launch Vehicle Technology affiliated to China Aerospace Science and Technology Corporation, introduced: “The rocket will pass through the windy area during the flight and suffer strong air currents.” He explained that people are riding bicycles. , If there is a sudden gust of wind on the side, it will be blown away.
In space, this lateral crosswind is much stronger than the wind that people perceive on land, which will affect the rocket's flight attitude.
If the wind speed is too high, it may also cause the rocket body to bend and deform, damage the rocket structure or even lead to disintegration.
For the rocket, the high-altitude wind is like a "checkpoint" set up in the air, which must be overcome in order to be successful.
In order for the rocket to "pass through the barriers" smoothly, observing and forecasting high-altitude winds before launching, and adjusting the launch time when necessary to avoid bad wind conditions, has become an indispensable link before the rocket launch.
The first commercial launch of SpaceX Falcon Heavy in 2019 was delayed due to high-altitude winds.
The launch of the Long March 8 rocket also almost passed the high-altitude wind.
"The launch time we aimed at at the beginning was earlier than the actual launch time, but just one day before the launch, the researchers predicted that the high-altitude wind over the launch site was abnormal and unsuitable for launch. Therefore, according to the results of the Meteorological Chamber of Commerce, the launch time was postponed by 2 days. "Said Wu Yitian, deputy chief designer of the Long March 8 rocket of the China Academy of Launch Vehicle Technology.
At 12:37 on December 22, Beijing time, the Long March 8 carrier rocket was successfully launched at the Wenchang Space Launch Site in China, sending five satellites into the predetermined orbit with "one arrow and five stars".
Photo by Su Dong
(2) How to deal with high-altitude wind?
In recent years, the China Academy of Launch Vehicle Technology has been carrying out relevant research and has taken a series of measures to reduce the impact of high-altitude wind on rocket launches, including statistics on wind speed and wind direction over the launch site in the past 10 years, and based on the maximum probability in the rocket design stage. The wind direction and wind speed will appear to carry out targeted design and so on.
In addition, before each launch, the researchers also need to measure and forecast the high-altitude wind on the launch day, and compensate for the high-altitude wind by designing the rocket flight program angle.
Wu Yitian said: "In order to hold the umbrella steady, people are used to align the direction of the umbrella with the direction of the wind to eliminate the lateral load. The method of high-altitude wind compensation is the same as that of a human umbrella. When possible, The longitudinal axis of the rocket points to the direction of the velocity of the rocket relative to the earth’s atmosphere, so that the angle between the longitudinal axis of the rocket and the direction of the velocity of the rocket relative to the earth’s atmosphere is zero." However, this method can only be used after the rocket has taken off to a certain speed, and Can't join suddenly.
In the development of the Long March 8 rocket, researchers have also adopted some new methods, such as autonomous anti-jamming control methods.
Pan Hao said: "This method allows the rocket to recognize and compensate for the interference during the flight. In other words, after the rocket feels the wind blowing, it can produce corresponding actions to weaken the wind interference." However, the Long March The launch of the No. 8 rocket for its first flight was in a special situation, and the wind speed at high altitude was too high. In order to complete the launch mission more safely, researchers finally chose to adjust the launch time from December 20 to December 22.
Wu Yitian said: "In the rocket design phase, if the wind field is considered too strict, the design will be conservative and the rocket structure will be too heavy. On the contrary, it will lead to the design leaning forward and the rocket structure is light, resulting in high wind loads on the launch day. The implementation of the launch. How to better balance the relationship between the two and better solve the impact of high-altitude wind on launches requires further exploration in the future." (End)