Roll program
Encyclopedia
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.
, the roll program is simultaneously accompanied by a pitch maneuver and yaw maneuver.
The roll program occurs during a shuttle launch for the following reasons:
Flight dynamics
Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw .Aerospace engineers develop control systems for...
that alters the attitude
Attitude dynamics and control
Spacecraft flight dynamics is the science of space vehicle performance, stability, and control. It requires analysis of the six degrees of freedom of the vehicle's flight, which are similar to those of aircraft: translation in three dimensional axes; and its orientation about the vehicle's center...
of a vertically-launched space launch vehicle
Launch vehicle
In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure....
. The maneuver is used to place the spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
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
Mission Control Center
A mission control center is an entity that manages aerospace vehicle flights, usually from the point of lift-off until the landing or the end of the mission. A staff of flight controllers and other support personnel monitor all aspects of the mission using telemetry, and send commands to the...
which is then acknowledged by the capsule communicator.
Space Shuttle launch
During the launch of a space shuttleSpace Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
, the roll program is simultaneously accompanied by a pitch maneuver and yaw maneuver.
The roll program occurs 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 altitudeAltitudeAltitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
- Simplifying the trajectory of a possible Return to Launch site abort maneuverSpace Shuttle abort modesA Space Shuttle abort was an emergency procedure due to equipment failure on NASA's Space Shuttle, most commonly during ascent. A main engine failure is a typical abort scenario. There are fewer abort options during reentry and descent...
- Improving radio line-of-sight propagationLine-of-sight propagationLine-of-sight propagation refers to electro-magnetic radiation or acoustic wave propagation. Electromagnetic transmission includes light emissions traveling in a straight line...
- Orienting the shuttle more parallel toward the ground with the nose to the east