Abstract
In order to insure reliable, leak-free operation of spacecraft propulsion hardware during long-term space missions, it is necessary to maintain hardware internal cleanliness at a level which allows no particles over 100 micrometres in size throughout the acceptance testing and delivery cycle of the hardware. To schieve this goal, it was necessary to derive and use specialized techniques, procedures, processes and hardware.
The spacecraft propulsion hardware involved consists of pressurant control assemblies, propellant isolation assemblies and pyrovalve subassemblies. In the end uses, the assemblies are formed into a system by an induction heating brazing operation on tube stubs to form the Viking Orbiter propulsion system.
Basic requirements for contamination control include a facility with FED-STD-209 Class 100 environments, and personnel trained in clean room practices and disciplines. The specific design, configuration and functions of the spacecraft hardware must then be considered to establish cleaning methods, cleanliness verification methods, and methods of maintaining specified levels of cleanliness. The techniques, methods, hardware designs, and hardware applications used to achieve the required contamination control are described.
