Vacuum Recovery of Polyimide Films Damaged with High Energy Electron Radiation

Ground- and space-based optical observations of space objects rely on knowledge about how spacecraft materials interact with light. In polymers, the changes in optical signature occur due to surface degradation caused by radiation induced chemical modification. This leads to altered reflectivity and deviation from a material's expected absorption/transmission properties. The optical fingerprint of commonly used spacecraft materials changes continuously under space weather exposure. Laboratory observations have also shown that these changes in a material's optical signature are to some degree transient. This work investigates the rate and degree of "optical healing" in vacuum and air exposure for electron damaged polyimide (PI) samples. Characterization of optical damage as a function of electron exposure and optical healing as a function of time in vacuum represents a major step toward a predictive model for optical characterization of space objects.