Operations analysis (study 2.1): Payload designs for space servicing
Potential modes of operating in space in the space shuttle era are documented. The October 1973 NASA Mission Model provides a definition of various NASA and non-DOD automated payload configurations when employed in an expendable mode. The model also specifies a launch schedule for initial deployment of payloads as well as for subsequent replacements at periodic cycles. This model and its associated payload definitions serve as a foundation for the data presented in this report. The reference model has been revised to reflect automated space servicing of payloads as an operational concept instead of the existing expendable approach. The indication is that the bulk of a payload's subsystems and mission equipment require no support over the lifetime of the program. However, failure of a single unit could result in loss of the mission objectives. When space servicing is employed, the approach is to replace only that unit causing the anomaly. This concept affords an opportunity to standardize space replacable units, as well as to reduce the expense of logistics support, by allowing multiple servicing on any single upper stage/shuttle flight.