Managed by Marshall Space Flight Center, the Space Tug concept was intended to be a reusable multipurpose space vehicle designed to transport payloads to different orbital inclinations. Utilizing mission-specific combinations of its three primary modules (crew, propulsion, and cargo) and a variety of supplementary kits, the Space Tug would have been capable of numerous space applications. This 1970 illustration depicts the primary modules of the Space Tug system along with some of the supplementary kits: lunar landing legs, extendable support arms, astrionics, and the satellite probe. The Space Tug program was cancelled and did not become a reality.