Atmospheric reentry
대기권 재진입
When an object that was in space comes back into the Earth's layer of air.
Overview
A spacecraft that was circling the Earth enters the air at close to 8 km per second. The air in front cannot get out of the way in time and is squeezed hard, which makes it extremely hot. The outside of the spacecraft is heated to well over 1,000 degrees Celsius. So a heat shield is attached, and the angle of entry is set precisely.
A crewed spacecraft or a rocket meant to be reused is steered down to a chosen place. Dead satellites and rocket pieces mostly just fall and burn up, but with large ones, some parts may survive and reach land or sea. So large objects are planned in advance to fall into a remote stretch of ocean where no one lives.
An everyday example
When you pump air into a bicycle tire quickly, the pump gets hot. Air heats up when it is suddenly squeezed. During reentry, that happens at an enormous speed.
Why it matters
It is counted as the most dangerous moment on the trip home from space. Reentry that is not steered is also why the news sometimes says no one knows where a piece of a satellite will land.
Also calledreentry