The International Space Station (ISS) Bipropellant Plume Contamination Model has been a vital tool for characterizing the thruster plume-induced contamination environment at the ISS but was not intended to be used for very short thruster pulse widths. This paper presents an updated model that ensures full start-up and shut-down phases are modeled for each thruster firing, when the majority of liquid phase contaminant mass is released. The updated ISS Bipropellant Plume Contamination Model prevents potential under-prediction of thruster plume-induced contamination due to visiting vehicle proximity operations and provides a way to take advantage of thruster start-up and shut-down performance data gathered during thruster test programs, if available.

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The return of International Space Station external experiments provides an opportunity to compare calculations of induced contamination with measurements from flight hardware. The Japan Aerospace Exploration Agency's Micro-Particle Capturer and Space Environment Exposure Device, which was attached to the exterior of the Russian service module, is one such experiment. The Micro-Particle Capturer and Space Environment Exposure Device experiment was purposed for particle capture (i.e., micrometeoroids and orbital debris) and materials exposure over varied durations. The experiment consisted of three identical units, which were mounted outside the International Space Station for periods ranging from 10 months to almost 4 years. X-ray photoelectron spectroscopy of various locations on the three Micro-Particle Capturer and Space Environment Exposure Device units has shown up to 950A of contamination deposition. Contamination analyses were performed to compare with measured contamination levels on each Micro-Particle Capturer and Space Environment Exposure Device unit. Material outgassing and thruster plume induced contamination were calculated using analytical and semi-empirical models developed by the Boeing Space Environments Team. Measurable levels of silicon-based contamination were predicted on the ram side, whereas a combination of silicon-based and thruster plume induced contamination was predicted for the wake side. Predictions of contamination depths were within a factor of 3, showing good agreement with measured contamination.

The International Space Station (ISS) solar arrays provide power that is needed for on-orbit experiments and operations. The ISS solar arrays are exposed to space environment effects that include contamination, atomic oxygen, ultraviolet radiation and thermal cycling. The contamination effects include exposure to thruster plume contamination and erosion. This study was performed to better understand potential solar cell optical performance degradation due to increased scatter caused by plume particle pitting. A ground test was performed using a light gas gun to shoot glass beads at a solar cell with a shotgun approach. The increase in scatter was then measured and correlated with the surface damage.

The Gateway space station will operate both as a lunar outpost and a hub for space exploration missions in support of a long-term human presence on the Moon, and is under development by NASA in collaboration with ESA, CSA, JAXA, and international commercial partners. Gateway will experience induced molecular contamination from sources including materials outgassing, venting, and the nominal operation of its chemical and electric propulsion systems. The degradation effects of molecular contamination on spacecraft are well-documented and understood, and predictive modeling tools have been developed to aid in the mitigation of such contamination effects in the mission design phase. Therefore, the Gateway Induced Environments and Thermal teams have worked with JPL Contamination Control to develop modular simulation tools for the prediction of molecular contaminant depositions across the mission life, and for use in requirements derivation and sensitivity assessments. Free-molecular transport and deposition of outgassing products onto sensitive Gateway receiver surfaces is calculated using a viewfactor matrix approach, while International Space Station (ISS)-heritage bipropellant plume models are used to evaluate contaminant fluxes generated by the operation of thrusters on Gateway modules and the Orion spacecraft. The alteration of optical properties, e.g. the solar absorptance, of contaminated surfaces is likewise calculated using an ISS-heritage semi-empirical model premised on flight and laboratory testing data. This framework is intended to support early identification of potential integration issues and establish a baseline for incorporating improved analysis and test data as the Gateway design matures.