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

In the context of counting down to a rocket liftoff or any other scheduled event, "t-minus" is a phrase used to indicate the time remaining until that event occurs. It is commonly used in the aerospace industry and during space missions to provide a standardized way of expressing the countdown.

The "t" in "t-minus" stands for "time," and the phrase is followed by a specific amount of time, typically in minutes and seconds, remaining until the planned liftoff or event. For example, if a rocket launch is scheduled to occur in 5 minutes and 30 seconds, you might hear it announced as "T-minus 5 minutes and 30 seconds" to indicate that there are 5 minutes and 30 seconds left before liftoff.

This countdown format helps ensure clear communication and synchronization among mission control personnel, astronauts, and other team members involved in the launch or event. It allows everyone to be on the same page regarding the timing and sequence of critical actions leading up to the liftoff.