What does "t-minus" mean when counting down to rocket liftoff?

Question

Josiah Adams · Accepted Answer

When time is represented on a graph or timeline or drawing, convention shows time increasing positive in the right direction and increasing negative (minus) to the left direction.

Suppose you had to make a chart or timeline to describe all the requirements to make that rocket liftoff at the exact time #T# it had to leave. The liftoff timing has to do with obtaining the correct trajectory, best weather conditions and many other concerns. There may be vey few times in a year that the timing will be opportune. In other words, you are timing negatively with numbers of increasing value from a future fixed time, starting with an exact time the rocket has to liftoff and planning every event backwards to the present. Ahead of a set liftoff time, T-minus can be measured in seconds, minutes, hours, days, weeks, months, and years.

Asher Cohen · Answer

undefined "T-minus" is a term used in rocket launches to indicate the time remaining until liftoff. It signifies the countdown, with "T" representing the time when the rocket is scheduled to launch. So, when you hear "T-minus," it means counting down to the moment of liftoff.