The molecular and liquid droplet thruster-induced contamination is
studied numerically for a 130 N ISS bipropellant thruster using
Navier-Stokes and DSMC flow solvers and a Lagrangian particle
tracking. The molecular sources contributing to the inorganic
components of the plume backflow contaminant are estimated, and a
qualitative characterization of the liquid droplet contribution to the
organic part of contaminant is conducted. The total calculated mass
flux of the molecular contaminant in the backflow region compares very
well with the experimental measurement on-board of Mir space station.
The computations show that approximately 20 to 30 per cent of the
droplets formed at the break up of the unburned propellant film at the
exit can contribute to the organic part of the backflow contaminant.