Why did Chang 'e V choose the return plan of "splashing water into space"?

"Traveling in space" means that the Chang 'e V's returner first enters the earth's atmosphere at high speed, then jumps up with the help of the lift provided by the atmosphere, and then re-enters the earth's atmosphere and returns to the ground. The technical term is high-speed reentry trajectory technology.

This return scheme is chosen to slow down the speed of the returner. There is no atmosphere in space, so the speed of the returner when it returns is so fast that the speed when it enters the atmosphere is close to the second cosmic speed (1 1.2km/s). Ultra-high speed will cause severe friction between the returner and the air, which may lead to complete combustion.

"Drifting water" will slow down the speed of the returner when it enters the atmosphere at high speed, reducing the speed of the returner to the first cosmic speed (7.9km/s).

Nevertheless, the returner will still have violent friction with the air, and its surface temperature can reach above 2000 degrees Celsius. If the returner introduces high temperature, it will have adverse effects on the moon rock and soil excavated by Chang 'e V.

Schematic diagram of Chang 'e V returner

To this end, China carefully designed the returner-there is a hole in the side with a propeller inside. When the returner flies in the atmosphere, it will not only be resisted, but also have a little lift. In this way, the returner can successfully return in the semi-ballistic jump mode.

I hope I can help you and adopt it.