Why does the launch of the shuttle rely on a specific time 'window'?

22nd July 2009
Shuttle launching

Asked by: Robin Harden, London

Imagine the shuttle has to dock with the ISS: it's a bit like trying to run alongside a specific horse on a moving merry-go-round. You could either keep chasing around until you catch up with the horse, or start running just as the horse is coming round. Likewise, the launch window is the period during which the shuttle can get into the right orbit using the minimum energy.