The MURI (Multidisciplinary University Research Initiative program) Center for Materials Chemistry in the Space Environment will seek to develop a quantitative and predictive understanding of how materials degrade or become passivated in the space environment. This is a critical research area for the DoD and NASA given the large and increasing dependence on satellites and manned spacecraft that reside in, or pass through, the low-earth orbit (LEO) space environment. The physical and chemical environment at LEO is not benign, but rather presents a highly aggressive materials oxidation and degradation situation, ensuring that this will remain a key long-term technical issue for the DoD and NASA as long-duration space activities become even more common than at the present time. For such orbits the interaction of atomic oxygen with thin-film coatings and both structural and nonstructural materials plays a dominant role in the long-term viability and performance of orbiting spacecraft.

This situation is further complicated by: (i) the high kinetic energy of gas-surface collisions in LEO, (ii) the synergistic chemical effects which will occur due to the presence of intense levels of solar radiation, (iii) the presence of electronically excited neutral and charged particles, which may further perturb the expected interfacial chemistry, and (iv) the presence of nanoscale interfacial defects produced via sputtering by high-energy particles.

This MURI Center brings together, arguably, the leading chemical researchers who, acting together, and in conjunction with DoD, NASA, and Industrial partners, can realistically tackle this complex materials problem. Delineation of the fundamental materials effects due to particle impingement and irradiation on materials used in LEO vehicles is a likely outcome of this effort. Recent developments in advanced experimental methods, theoretical methodology, computer modeling, and synthesis suggest that the time is now appropriate to launch such a concerted multidisciplinary effort to develop a predictive understanding of the surface and materials chemistry which dominate the time-evolution of materials behavior and failure in the harsh LEO environment.

This MURI Center assembles the needed capabilities to have significant impact on this topic, including: experimental atomic beam gas-surface scattering and imaging studies involving neutral and ionic species in relevant reaction environments, surface photochemistry expertise, synchrotron-based measurement and irradiation, synthesis of structural and conducting polymers, and theory involving realistic molecular-level models using quantum chemical methods, rate calculations, and simulations of morphological interface evolution. The 7 members, located at the U. of Chicago, Montana State, Northwestern, Notre Dame, Penn State, and Yale, have the required complementary expertise, in many instances having pioneered the experimental, theoretical and synthetic methods in use today, to address the underlying chemical and physical issues which are needed to predict materials evolution in the LEO environment. Such understanding is presently lacking, and is needed for a wide-range of metallic, organic, polymeric, semiconductor, and insulating materials.

As an added benefit, this MURI effort will further augment our understanding of gas-surface collisional energy and momentum transfer, supplying data needed to accurately assess orbital decay in the space environment. To summarize, the proposed MURI Center is well positioned to have significant impact on DoD's urgent need to develop advanced, time-stable materials for use in space, leading, ultimately, to reduced system failure due to materials degradation in long-duration LEO operations.

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