Launch window

Launch window is a term used in aerospace to describe a time period in which a particular rocket must be launched. For trips into Earth orbit most any time will do, but if the spacecraft intends to rendezvous with another (or a planet, or other point in space) the launch must be carefully timed so that the orbits overlap at some point in the future. If the rocket does not launch in the "window", it has to wait for the next one before it can go.