Assessing Mechanical Properties of Spacecraft Materials under Simulated Low Earth Orbit Atomic Oxygen Conditions
During a space mission, spacecraft surface materials are exposed to various damaging environmental factors including high-energy photons, electrons, atomic oxygen (AO) neutrals and ions, micrometeoroids and orbital debris, vacuum, and large temperature fluctuations. The resulting change in spacecraft material properties can significantly impact the performance and durability of spacecraft systems. Even though all aspects of the space environment can lead to the deterioration of spacecraft components, in low Earth orbit (LEO), the threat posed by AO is especially severe in terms of structural and optical damage, particularly to exterior spacecraft components that are susceptible to oxidation. A comprehensive understanding of material AO-induced weathering is essential for mission planning in the LEO environment. The presented work aims to evaluate the alterations in mechanical properties of selected innovative spacecraft materials and surface electronic system designs, such as Kapton® CR film coated front and back-side with polyimide coating containing AO-resistant filler, Kevlar EXO, and Bendable Electrodynamic Dust Shield (BEDS) architecture, under simulated AO exposure, utilizing the photoelasticity phenomenon in which birefringence is induced in a material when it is subjected to mechanical stress. Changes in stress patterns during the deformation of AO-exposed polymers were assessed using a large-field polariscope under varied deformation types. Patterns of colors were used for qualitative evaluations of residual stress. The stress patterns of the AO-exposed polymers were compared to those of the unexposed ones. Also, these patterns were correlated with data from Bidirectional Reflectance Distribution Function (BRDF) and surface morphology studies.