Roll program

A roll program or tilt maneuver is an aerodynamic maneuver that alters the attitude of a vertically launched space launch vehicle. The maneuver is used to place the spacecraft on a proper heading toward its intended orbit.

A roll program is completed shortly after the vehicle clears the tower. In the case of a crewed mission, a crew member (usually the commander) reports the roll to mission control which is then acknowledged by the capsule communicator.^[1]

Space Shuttle launch

Space Shuttle Atlantis performs the roll maneuver shortly after launching from Kennedy Space Center on STS-129.

During the launch of a space shuttle, the roll program was simultaneously accompanied by a pitch maneuver and yaw maneuver.^[2]

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.^[2]

References

1. NASA - STS-117 Lift Off! ATLANTIS: "Houston, Atlantis. Roll program." Voice 1: "Roger roll, Atlantis".
2. Jenks, Ken. "Why does the shuttle roll just after liftoff?".