Before revision: The roll program occurred during a shuttle launch for the following reasons: To place the shuttle in a heads down position Increasing the mass that can be carried into orbit Increasing the orbital altitude Simplifying the trajectory of a possible Return to Launch site abort maneuver Improving radio line-of-sight propagation Orienting the shuttle more parallel toward the ground with the nose to the east Titan II and Saturn V launch Titan II and Saturn V launches also required roll programs.
After revision: (this was actually the initial reason - a 20%DIF > payload increase due to more efficient aerodynamics and moment balancing between the boosters and main engines)NASA-CR-129000, TR-243-1078 (1972)The roll program occurred during a shuttle launch for the following reasons: To place the shuttle in a heads down position Increasing the mass that can be carried into orbit Increasing the orbital altitude Simplifying the trajectory of a possible Return to Launch site abort maneuver Improving radio line-of-sight propagation Orienting the shuttle more parallel toward the ground with the nose to the east Titan II and Saturn V launch Titan II and Saturn V launches also required roll programs.