Main Engine Cutoff, First-Stage Separation

A United Launch Alliance Atlas V 541 rocket is shown carrying NOAA’s GOES-T satellite. Photo Credit: NASA/Kim Shiflett

Have you ever wondered what the three numbers (541) on United Launch Alliance’s Atlas V 541 rocket stand for? The numbers signify a payload fairing, or nose cone, that is approximately 5 meters (16.4 feet) in diameter; 4 solid-rocket boosters fastened alongside the central common core booster; and a 1-engine Centaur upper stage.

Just an interesting fact to throw in while we announce main engine cutoff (MECO) has occurred and the first stage has separated from the rocket. Coming up next, in about 10 minutes, will be Centaur main engine start #2, followed by main engine cutoff #2 about five minutes later.