The propulsion system of a projectile is very important for the aerospace industry. To perform space exploration mission, controlling position and posture of the projectile in the terminal stage is very important. In this study, a new lateral thrust system is proposed to control the position and posture of the projectile at the terminal stage. Based on nozzles in a lateral thruster, a high-speed projectile can instantly change its position and posture. After changing its position and posture, reverse thrust is generated to control unnecessary movements for stabilizing. Based on various tests, the operation and performance of the nozzle opening device (NOD) of the separation mechanism were validated. As a result, excellent reproducibility was confirmed with standard deviation of 0.057 ms for the time from the end of igniter operation to the start of NOD separation. The internal pressure of the chamber and NOD separation time were inversely proportional to each other with a linear relation. The internal pressure of the chamber and flight speed of NOD were also proportional to each other. The flight speed of NOD was 37.53 m/s at the maximum expected operation pressure (β), 30.26 m/s at 0.5 β, and 17.05 m/s at 0 psi.