Attitude control
Attitude control was provided by J-2 engine gimbaling during powered flight and by the two APS modules during coast. APS modules were used for three-axis control during coast phases, roll control during J-2 firings, and ullage for the second ignition of the J-2 engine. Each APS module contained two thrusters providing thrust for roll and pitch, another thruster for yaw, and one thruster for ullage. Each module contained its own propellant tanks of dinitrogen tetroxide and monomethyl hydrazine as well as compressed helium to pressurize its propellants.