The purpose of the system was two-fold: to reduce the cost of spaceflight by replacing the existing method of launching capsules on expendable rockets with reusable spacecraft; and to support ambitious follow-on programs including permanent orbiting space stations around Earth and the Moon, and a human landing mission to Mars.

The group responded in September with the outline of the STS, and three different program levels of effort culminating with a human Mars landing by 1983 at the earliest, and by the end of the twentieth century at the latest.

The system's major components consisted of: The tug and ferry vehicles would be of a modular design, allowing them to be clustered and/or staged for large payloads or interplanetary missions.

A second part of the system, Space Station Freedom, was approved in the early 1980s and announced in 1984 by president Ronald Reagan.

The MSFC space tug was designed to handle a number of missions including satellite repair, transfer to geosynchronous orbit, and as the name implies, towing payloads to the nuclear shuttle.