Contamination modeling in Europe has long been based on physical mechanisms, such as desorption. However other physical mechanisms, such as diffusion, evaporation or mixing effects exist. These alternative mechanisms were experimentally evaluated and modelled. It was yet observed that, without an experimental capability to reliably separate the (re)emitted chemical species, it is very difficult to determine whether the modeling and its underlying physical mechanisms are representative of reality, or simply a mathematical fit of reality. This is the reason why in the last years emphasis was put on the experimental separation of species, mostly through TGA/MS coupling. This paper presents a review of these efforts and promising results on species separation to reach a really physical modeling of outgassing, deposition/reemission and UV synergy.
Increasingly satellites are carrying on-board bipropellant thrusters, especially for interplanetary missions. Many of these spacecraft are also equipped with surface-sensitive instruments, such as telescopes and detectors, which, due to the required configuration, might be impinged by the bipropellant thruster plumes and therefore contaminated by plume exhaust products. At present, there are no European analysis tools capable of determining the effects of such propulsion systems on surfaces sensitive to contamination in the preliminary design phase. This may result into a need to modify the spacecraft design in a later development phase in order to mitigate contamination effects. The consequences are additional costs, delay on schedule and possible reductions of scientific goals. This paper emphasizes the need for a tool to be used at the preliminary stage of a satellite design to analyse the contamination effects of bipropellant thruster plume impingement on sensitive surfaces. It also describes a possible approach/architecture to be used for this tool.