Complex sentence: The Attitude and Articulation Control Subsystem (AACS) controls the spacecraft orientation, maintains the pointing of the high-gain antenna towards Earth, controls attitude maneuvers, and positions the scan platform.
Split into simpler sentences: The Attitude and Articulation Control Subsystem (AACS) controls the spacecraft orientation (its attitude). It the high-gain antenna pointing towards the Earth, controls attitude changes, and points the scan platform.