If a lunar mission launch feels like a can’t-miss event, you’re in the right place.
But the shorthand used by launch directors can sound like an unfamiliar language.
Here are a few things to listen out for today:
If the launch is a go, that means things are on track to take off. If it’s a no go, the launch may be postponed.
As mission teams progress through the countdown, expect to hear SLS, which stands for Space Launch System, to indicate the rocket. If the word nominal is used, it means that things are normal or going as planned.
During the countdown, you will hear L Minus and T Minus times.
L Minus is used to indicate the time until liftoff in hours and minutes, while T Minus corresponds with the events included in the launch countdown, like the retracting of the Crew Access Arm, which enables astronauts to board the spacecraft.
If the launch team announces a hold, this indicates a natural pause in the countdown, which is intended to allow for tasks to be performed or for a slight delay so that liftoff will align with a specific launch time that doesn’t disrupt the schedule.
The ground launch sequencer, or a computer that tells the rocket when to launch, will initiate terminal count. This is the final, and largely automated, phase of countdown that spans the last 10 minutes before liftoff.
After the engines start up and the booster ignites, umbilical separation, or the disconnecting of power cables and fuel lines, will take place — the last step before the rocket launches.
Here’s more lingo that will help you sound like an astronaut as you follow the mission beyond launch day.