Maintainability Design Requirements for Future Space Systems

Design requirements which consider maintenance capability can be expected to be quite different for space system application when compared to those currently in use for today´s weapon systems. Needs will vary, as will the base for the definition of quantized criteria. Maximum urgency is placed on crew safety, mission success, and meeting a launch window. The expressions for quantitative maintainability design criteria will shift from the familiar ``Meantime´´ base to one of ``Allowable Time,´´ ``Probability of Repair Within Time Limits,´´ and ``Expenditure of Human Energy.´´ This paper explores the operational requirements for maintainability in future space systems, discusses interface problems, and defines quantized maintainability objectives for the different applications of 1) spacecraft, 2) space stations, 3) boosters, and 4) support equipment.