Sources inherent to materials are: particles originating from manufacturing (machining, sawing), handling (e.g. for brittle materials such as certain paints) or wear (friction); degradation of binder under different environments (e.g. AO, UV) resulting in loose filler; crack formation and subsequent flaking as a result of thermal cycling; formation of particles due to oxidation in an atomic oxygen environment.
Sources external to materials are: Dust particles caused by atmospheric fallout (dust) during assembly, integration and storage or by human sources during such activities (e.g. hair, skin flakes, lints or fibres from garments); particles produced during spacecraft propulsion or attitude control operations, the functioning of moving parts (such as shutters), and water dumps; particles resulting from micrometeoroid or debris impacts on materials.