The low cost development, test, and production of a commercial STS upper stage: TOS

The Space Transportation System (STS) has to compete for commercial payload launches with a variety of expendable launch vehicles (ELVs). Many of these payloads have to be placed into a final orbit which cannot be provided by the Shuttle Orbiter. An upper stage booster is, therefore, needed. The Transfer Orbit Stage (TOS) is being developed to satisfy this need at a competitive user cost. The requirements for the development and test program for the TOS system are related to a 'minimum cost - minimum risk' approach. In this context, the use of existing flight qualified 'off the shelf' hardware is to be maximized. Attention is given to a TDS system description, the development test objectives, and the TOS test program results.