On Double Eleven, some of our tailmen chose overseas purchasing, and at 4:30 a.m. on the 24th, at the Wenchang Space Launch Center in Hainan, China also began the first lunar "purchasing" trip to collect some "moon" for everyone. The melon-eating teenagers were quite excited, but after carefully pondering, a question came to mind-
Why do such proud things do in the early hours of the morning?
The timing of major events, that is naturally considered ~ ~
First of all, this point in time facilitates the design of the lunar orbit. Lunar exploration, like Mars exploration, is a deep space exploration, and in the design of rocket launch orbits, engineers must take into account factors such as the relative position of the Earth and the Moon.
Specifically, the selection of the launch time satisfies the restrictions of the position relationship between the Earth and the Moon, the constraints of the probe's Earth-Moon transfer time, the rocket firing and taxi time constraints, and the returner re-entry voyage. After comprehensive consideration, the early morning launch can meet various constraints.
From the perspective of solar influence, such sophisticated detection activities need to minimize the impact of solar activity on Chang'e-5. When the Long March 5 rocket flies into the universe, it is exactly when the earth directly blocks the sunlight, and the impact of solar radiation, sunspots, solar storms, etc. on the Chang'e-5 probe will be significantly reduced.
From the meteorological conditions, there are fewer clouds in the sky in the early morning, which is conducive to the transmission of signals.
Space launch is not an easy task, not as simple as an airplane setting sail. In the early morning, because there is no sunlight and the temperature drops, the evaporation of the surface of the earth decreases, and the clouds in the air are also significantly reduced and thinned. This kind of weather conditions, which are conducive to signal propagation, are also conducive to the control of Chang'e 5 by researchers on the ground. Moreover, the atmospheric conditions in the early morning are relatively stable, and there will be no sudden weather changes, which is also conducive to the launch of the Long March 5 rocket.
4 a.m. view of a coastal city (less clouds in the sky)
In addition, when the sky is dark, it is convenient to observe. Launched in the early morning, astronomical equipment such as telescopes can be better used to summarize the observed launches. If the Long March 5 is launched during the day, the strong sunlight will interfere with the telescope and make it impossible to accurately capture the specific situation of the rocket launch.
At the same time, the night air is cooler, and the fairing of the "Fat Five" is lower in temperature and more protective of the fairing.
Finally, the scientists also took into account the battery factor. Battery capacity is limited, so Chang'e 5 must also have sunlight to fly into the universe alone. Launched in the early morning, after it reaches tens of thousands of kilometers, the battery can obtain a steady stream of light energy at the maximum light angle, so as to carry out sustainable work.
In summary, the relationship between the position of the earth and the moon, solar activity, meteorological conditions, observation conditions, battery energy storage... Well, this 4:30 a.m. decision has so many doorways!
Author: Chen Shan, Meteorological Analyst and Meteorological Engineer of China Meteorological Administration.