Launch windows

[mycatis]

When talking about space travel what is a "launch window" I know they need to wait for it but dont understand why, If they have the power to go up what's stopping them? Sorry if I sound really dumb

cheers

[fo3nix]

this may be totally wrong, but just from my own thoughts, i'd say its probably a window of time they can launch in while, say, the skies are clear above.

[newtron]

here's a helpful link:

http://liftoff.msfc.nasa.gov/academy/rocket_sci/launch/launch_window.html

[brachiopod]

It's not just conditions here on Earth that govern a window.

Depending on the mission's objective, the alignment of certain planets or the degree of rotation of a body can define the 'launch window'.

For example, a long distance space flight (such as those made by probes to the outer planets of the solar system) rely on 'sling-shotting' of the gravitational fields of closer planets in order to reach maximum speeds with minimum fuel. Thus, their alignment is important.

The 'maximum launch window' will be narrowed by the combination of required conditions. For example (and hyperthetically speaking);
Distant planet X is only in the right part of its 74 year orbit for a period of two years. (Launch Window = 2 years)
Within that period, planet Y is only in the right position to 'sling-shot' off for 5 months. (LW is now 5 months)
Of this, the first 3 months are during the hurricane season at the launch site (LW = 2 months)
The President is on holiday for the last two weeks (LW = 6 weeks) etc etc.

In addition, the rotation of the Earth will mean that the LW may be further limited to a certain few hours of each day within that period.

[mycatis]

Thanks Brachiopod thats what I wanted to know, well explained :)