An attitude control and thrust boosting system for a space launcher, comprising a rocket engine provided with an exhaust nozzle; wherein said exhaust nozzle comprises a divergent portion configured to make a supersonic gas flow exit through an exit section defined by a given angle of divergence with respect to a longitudinal axis (A L) of the rocket engine; the attitude control and thrust boosting system comprising: • a plurality of flaps (110,111,112,113) arranged around the exit section, shaped so as to extend the divergent portion of the exhaust nozzle, mechanically decoupled from said exhaust nozzle and which can be actuated to take different angular positions with respect to the longitudinal axis of the rocket engine; and • control means configured to - receive quantities indicative of an actual attitude of the space launcher and an ambient static pressure, - cause the flaps (110,111,112,113) to take a neutral angular position where the flaps (110,111,112,113) are inclined, with respect to the longitudinal axis of the rocket engine, according to an inclination angle greater than, or equal to, the given angle of divergence, - control the neutral angular position taken by the flaps (110,111,112,113) according to the ambient static pressure by reducing the inclination angle as the ambient static pressure decreases, and - make one or more flaps (110,111,112,113) take an angular position different than the neutral angular position according to the actual attitude of the space launcher and to a required attitude for said space launcher. • a plurality of flaps (110,111,112,113) arranged around the exit section, shaped so as to extend the divergent portion of the exhaust nozzle, mechanically decoupled from said exhaust nozzle and which can be actuated to take different angular positions with respect to the longitudinal axis of the rocket engine; and • control means configured to - receive quantities indicative of an actual attitude of the space launcher and an ambient static pressure, - cause the flaps (110,111,112,113) to take a neutral angular position where the flaps (110,111,112,113) are inclined, with respect to the longitudinal axis of the rocket engine, according to an inclination angle greater than, or equal to, the given angle of divergence, - control the neutral angular position taken by the flaps (110,111,112,113) according to the ambient static pressure by reducing the inclination angle as the ambient static pressure decreases, and - make one or more flaps (110,111,112,113) take an angular position different than the neutral angular position according to the actual attitude of the space launcher and to a required attitude for said space launcher. - receive quantities indicative of an actual attitude of the space launcher and an ambient static pressure, - cause the flaps (110,111,112,113) to take a neutral angular position where the flaps (110,111,112,113) are inclined, with respect to the longitudinal axis of the rocket engine, according to an inclination angle greater than, or equal to, the given angle of divergence, - control the neutral angular position taken by the flaps (110,111,112,113) according to the ambient static pressure by reducing the inclination angle as the ambient static pressure decreases, and - make one or more flaps (110,111,112,113) take an angular position different than the neutral angular position according to the actual attitude of the space launcher and to a required attitude for said space launcher.