Propulsion subsystems in a spacecraft aid in preserving the three-axis stability and the control spin. In addition to it, they also help in carrying out manoeuvres and to bring about slight alterations in trajectory. The superior ones called ?engines? can infact, generate an acceleration of large torques in volume to sustain the stability of a solid rocket motor during burning phase. The delta-V for simple tasks like the interplanetary trajectory correction manoeuvres, orbit trim manoeuvres, reaction wheel de-saturation manoeuvres and the routine three-axis stabilization or spin control, are arranged with the support of rather smaller engines that can provide with a force between 1N and 10N. While AACS, kick-off many of regular actions of the propulsion subsystems, all these actions are regulated by CDS.

Magellan spacecraft had four rocket engine modules, where each module housed two 445 -N engines, one gold-colored 22-N thruster, and three gold colored 1-N thrusters.

Each engines had different tasks to fulfil. The 445 -N engines had to manage the mid flight course corrections and take care of orbit-trim corrections also had to steer the spacecraft during the burning of solid rocket motor on entering the venus orbit. While the 22-N thrusters protected the spacecraft from undulating on the manoeuvres, the 1-N thrusters gave the necessary acceleration for wheel de-saturation and small manoeuvres.