The Thiokol TU-844 motor was to provide propulsion for the McDonnell Douglas Spinning Solid Upper Stage, which was designed to launch Atlas Centaur-class payloads from the Space Shuttle. A slightly modified stage 3 Minuteman 3 with TVC and roll control systems removed. However, the motor was adapted as the perigee boost motor for the Leasat and JCSat telecom satellites..