- Launch window
Launch window is a term used in
aerospace to describe a time period in which a particularrocket must be launched. If the rocket does not launch within the "window", it has to wait for the next one before it can be launched.For trips into largely arbitrary
Earth orbit s almost any time will do, but if thespacecraft intends to rendezvous with a space station or another vehicle that is already in an orbit the launch must be carefully timed to occur around the times that the target vehicle's orbital planes intersects the launch site.To go to another planet without using any kind of
gravitational slingshot , if eccentricity of orbits is not a factor, launch windows are periodic according to thesynodic period ; for example, in the case of Mars the period is 2.135year s, i.e. 780day s. In other cases launch windows are irregular. Sometimes rare opportunities are used. When a rare opportunity is missed, sometimes another target has to be selected.For launches above
low Earth orbit (LEO), the actual launch time can be somewhat flexible if aparking orbit is used, because the inclination and time the spacecraft initially spends in the parking orbit can be varied.Launch windows are often calculated from
porkchop plot s which show the delta-v needed to achieve the mission, plotted against the launch time.Related terms
The term 'launch window' was popularized with the
world wide coverage of the earlyspace program . People inbusiness came to use the phrase window of opportunity to be defined by specific range of dates, within which, they must take action or miss the chance toleverage themarketplace to their benefit.ee also
*
Collision avoidance
*Delta-v
*Delta-v budget
*Hohmann transfer orbit
*Interplanetary travel
*Space rendezvous
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