Launch and sites
T-0
T-0
The reference instant of liftoff; the count counts from it.
After T-0 the clock runs as T+ elapsed time.
Related terms
- Pad turnaround — Time to reset a pad between flights.
- Weather criteria — The weather rules a launch must satisfy.
- Range — The ground corridor the rocket overflies, kept clear.
- Downrange — The area ahead along the flight path.