The International Space Station (ISS) sounded the alarm on Monday because the space debris threatened to pass too close. Several media have reported this.
Four astronauts moved to their Crew Dragon for safety reasons, the other three to a Soyuz. In an emergency, such as a catastrophic collision, those rescue ships can quickly reach her home.
Flight control plans to fire missiles to get out of the way of the space debris. But this planning takes time.
It is not yet known exactly what the space debris is.