MURI Center for Materials Chemistry in the Space Environment

摘要

MURI research activities, involving strong interactions between experiment and theory, including interactions with AFRL, NASA, and Boeing, have advanced knowledge of condensed-phase and gas-phase reactions relevant to materials reactivity in LEO. We have: elucidated the mechanism by which graphite is eroded by high-kinetic energy atomic oxygen; quantified the pathways by which organic molecules react with atomic oxygen in regimes not found in the terrestrial environment; explored hyperthermal O chemistry with gas-phase model organic compounds to delineate quantum chemical reaction dynamics appropriate to LEO; discovered a new gas-surface collisional energy- transfer mechanism in which atoms become embedded and re-emitted from thin organic films with specific directionality and excess momentum, contributing to a refined understanding of collisional energy transfer; developed new theoretical methodologies for treating rare events which can dominate the morphological evolution of eroding interfaces - including the first three- dimensional code that incorporates realistic interfacial chemical reactions with large surface area processes; explored synergistic effects in polymer degradation involving atomic oxygen and short-wavelength radiation commensurate with LEO solar illumination; collaborated with AFRLs to understand the efficacy of hybrid organic/inorganic POSS materials; and are important partners in orbital experiments, MISSE-5 and -6, which seek to better define materials degradation in LEO.