GPM Performs Yaw Turn, Continues Calibration
On March 17, the team executed GPM's first scheduled yaw turn to turn the orientation of the spacecraft 180 degrees. Yaw is the left/right orientation in the horizontal plane of the spacecraft's motion. The spacecraft is now "flying backwards." Yaw maneuvers will be performed approximately every 40 days for spacecraft thermal control, as the angle between the spacecraft's orbit and the sun changes. This keeps the side of the spacecraft that is designed to remain cold from overheating. Yaw maneuvers are performed primarily using the spacecraft's reaction wheels.
March 19, the team performed a 50-second delta-V maneuver, an increase in speed to boost the altitude of its orbit, using its thrusters. GPM has twelve thrusters: four forward and eight aft. Wednesday's maneuver was the first delta-V performed using the forward thrusters, since the spacecraft is now in in the opposite orientation after the yaw turn.