The inertial upper stage - A key transportation element of future unmanned planetary missions

The inertial upper stage (IUS), described in the present paper, is being developed to provide a highly reliable cost effective vehicle with built-in flexibility and adaptability for integration with the space shuttle. It will accurately deliver spacecraft into a wide range of earth orbits. Two high-performance solid-propellant rocket motors, an interstage structure, and an avionics module are the fundamental building blocks for the two-stage, twin-stage, and twin-stage-with-spinner configurations. The simplicity of this IUS family is illustrated.