"The Active Mass Balance Auto-Control (AMBAC) is a fundamental technology that allows for thruster-less maneuvering in the zero-G environment of space by mobile suits by means of precise movement control of their limbs."

"AMBAC works by leveraging Isaac Newton's Third Law of Motion (When there's an action there is an equal and opposite reaction) with regard to inertia to effect changes in direction. For example, if we place a person in a micro-gravity environment where friction is negligible (i.e. space), and ask him to place his left arm to his chest then swing it out to the side, the resulting inertia of the arm movement would result in the rest of his body turning the other direction in order to conserve angular momentum. Then when the motion of the arm stopped, the rotation of the body would also stop. The AMBAC system coordinates movements and micro-movements precisely, allowing a continuous balanc e and stability without expending reaction mass. For the most part, AMBAC is invisible to the naked eye, as the shifts are slight. The system can be used to dodge incoming projectiles or small objects as the arms and legs of a mobile suit account for a significant portion of its total mass. The AMBAC system also allows the center of mass to shift outside of the body. AMBAC is by its nature limited to re-orienting the unit about its center of mass, and is not a substitute for propulsion. It is often used in conjunction with the propulsion system to quickly turn the unit and shorten aiming speed as well as directing the main thrusters. The system is similar in principle to the momentum wheel system used in present day satellites, though obviously more complex. Mobile suits performing AMBAC motions would presumably move similarly to present-day astronauts performing extra-vehicular activity: both typically having roughly similar body structure, their use of that mass to control their rotation would presumably be similar, even if calculated by different means."