[ad_1]
Original title: Why was the Chang’e-5 plan launched in the early morning hours of tomorrow? Source: China Science and Technology Network
The reporter learned from the National Space Administration that around 6:30 p.m. on November 23, 2020, the Long March 5 Yaowu carrier rocket began to be filled with liquid oxygen and cryogenic propellant liquid hydrogen, and is scheduled to launch between 4 am and 5 am on the 24th. homework. This is the second applied launch of the Long March 5 series of carrier rockets. It will transport the probe of the Chang’e 5 lunar exploration project to the Earth-Moon transfer orbit and implement the first mission of sampling and return of extraterrestrial celestial bodies of China.
Why choose to launch it early in the morning? According to the National Space Administration, the Yaowu Long March 5 rocket launch window time is based on a comprehensive consideration of the relationship of the earth-moon position and other factors, and the best launch time after the orbital design.
You still don’t understand, do you? Then listen to a detailed introduction by Qian Hang, a Ph.D. from the Department of General Design of the First Academy of the China Aerospace Science and Technology Corporation.
Qian Hang said, first, that the early morning launch is more conducive to the design of the rocket orbit to the moon.
In the design of the rocket launch orbit, the relative position of the Earth and the Moon must be taken into account, so compared to launch missions such as communication satellites, there are more limitations. For the launch of the Chang’e-5 probe, the most suitable one should be selected under the conditions of meeting the constraints of the positional relationship between the earth and the moon, the limitations of the rocket launch direction, and time glide, the probe-to-moon transition time, and the reentry range of the returner. Lunch time. After thorough consideration, a startup window is determined that can meet various restrictions.
The second is to reduce the impact of solar activity on “Chang’e-5”.
Solar activity is a threat to Chang’e-5, especially the solar wind will interfere with the propagation of electronic signals, directly affecting the manipulation of the probe by scientific researchers. Choose to launch early in the morning. When the rocket is flying, the earth can block the sun to avoid this effect.
Third, there are fewer clouds in the sky at night, which helps the signal spread.
Weather is an important factor to consider for a space launch mission. Especially for this mission, experts will conduct research on the weather conditions in advance to make sure the weather is in the best condition during launch. The weather conditions in the early morning are relatively stable and there will be basically no sudden changes, which is more beneficial for the launch mission. Also, fewer clouds are more conducive to signal propagation.
The fourth is to facilitate observation.
The overall brightness of the environment is low in the early morning and the launch vehicle is very striking when flying into space with flames, favoring ground optics and measurement equipment to track targets and gather relevant information. At the same time, the air is cooler at night, allowing the rocket fairing to cool down.
In addition, Qian Hang said that the spacecraft’s battery capacity is limited, and the long-distance flight of the Chang’e-5 in space must be illuminated by the sun. Choose to launch early in the morning, when the Chang’e 5 flies tens of thousands of kilometers, the battery can get a constant flow of solar energy through the maximum lighting angle.
