Here’s a fun question that not only have I myself asked, but I get asked fairly often, why do we hear a call out like “roger roll” or “roll program complete” at which point we can see the rocket rotate or roll on its X axis… The best example of this was the Space Shuttle which had a very obvious and dramatic roll program. As soon as it cleared the tower, you can see it making a very impressive and sometimes scary looking roll. Now a maneuver like this makes sense when a vehicle is asymmetrical like the Space Shuttle, but why do cylindrical rockets like the Saturn V, Titan, Atlas, Delta IV etc etc even bother doing a roll? Can’t rockets just tip over in whatever direction they need to go? Do a little pitch here, a little yaw there just as long as the pointy end is going the direction it’s intended to go, who cares which side of the rocket is facing the Earth and which side is facing space… right? So today we’ll first define the pitch, yaw, roll and their corresponding axis on a rocket, then we’re going to dive into why a rocket rolls in the first place, take a look at launch azimuths and their relationships to trajectories and we’ll look at some unique solutions to orientations including some rockets that don’t roll on ascent to align with their trajectory.