The time span during which a spacecraft can be launched safely and best accomplish its mission trajectory. This can vary from a few hours to a period of several weeks.
The launch window depends on such factors as the weather, the Earth's rotation and orbital motion, and the motion of the destination planet or rendezvous target, for example the International Space Station. Launch windows for missions to the planet Mars occur approximately only every 26 months.
Subjects: Astronomy and Astrophysics.