This clause deals with the induced molecular and particulate environment in the vicinity of and created by the presence of a spacecraft in space. It is meant mainly to aid in the definition of the contamination environment of a satellite. Possible physical models and computer tools are in Annex K.
The quantitative modelling of this contamination environment is very complex. This is due to the high number of materials involved, with a variability of outgassing characteristics. Furthermore, there are interactions of the outgassing products with surfaces, residual gas and with other environmental parameters such as solar radiation and atomic oxygen.
The contamination analysis, which necessarily is very much dependent on a specific project/application, cannot be more detailed in this standard. ECSS-Q-ST-70-01 defines amongst others the requirements to be followed and guidelines to be taken into account in order to control the particulate and molecular contamination within the specified limits during mission. It also includes a list of potential contamination effects on space hardware.