Three RS-25 engines, also known as the Space Shuttle Main Engines (SSME), were mounted on the orbiter's aft fuselage in a triangular pattern. The engine nozzles could gimbal ±10.5° in pitch, and ±8.5° in yaw during ascent to change the direction of their thrust to steer the Shuttle. The titanium alloy reusable engines were independent of the orbiter vehicle and would be removed and replaced in between flights. The RS-25 is a staged-combustion cycle cryogenic engine that used liquid oxygen and hydrogen and had a higher chamber pressure than any previous liquid-fueled rocket. The original main combustion chamber operated at a maximum pressure of . The engine nozzle is tall and has an interior diameter of . The nozzle is cooled by 1,080 interior lines carrying liquid hydrogen and is thermally protected by insulative and ablative material.
three rs-25 engines also known as the space shuttle main engines (ssme) were mounted on the orbiter's aft fuselage in a triangular pattern the engine nozzles could gimbal ±105° in pitch and ±85° in yaw during ascent to change the direction of their thrust to steer the shuttle the titanium alloy reusable engines were independent of the orbiter vehicle and would be removed and replaced in between flights the rs-25 is a staged-combustion cycle cryogenic engine that used liquid oxygen and hydrogen and had a higher chamber pressure than any previous liquid-fueled rocket the original main combustion chamber operated at a maximum pressure of  the engine nozzle is tall and has an interior diameter of  the nozzle is cooled by 1080 interior lines carrying liquid hydrogen and is thermally protected by insulative and ablative material