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.