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Countdown

A countdown is a sequence of backward counting to indicate the time remaining before an event is scheduled to occur. NASA commonly employs the terms "L-minus" and "T-minus" during the preparation for and anticipation of a rocket launch, and even "E-minus" for events that involve spacecraft that are already in space, where the "T" could stand for "Test" or "Time", and the "E" stands for "Encounter", as with a comet or some other space object. Other events for which countdowns are commonly used include the detonation of an explosive, the start of a race, the start of the New Year, or any anxiously anticipated event. An early use of a countdown once signaled the start of a Cambridge University rowing race. One of the first known associations with rockets was in … more »