Surface Modification of Space Exposed Materials Induced by Low Energetic Proton Irradiation

The aim of this paper is to verify if commonly occurring space debris materials change their reflectivity and morphology after being exposed to low energy protons. Therefore, a set of six different materials frequently used in spacecraft engineering was irradiated with low energy (100 keV) protons to simulate the aging of their surfaces due to space radiation in low Earth orbit (LEO). A microscopic and spectroscopic analysis of the irradiated samples reveals that the tested materials containing organic polymers (Polytetrafluoroethylene (PTFE) and carbon fiber reinforced plastic (CFRP)) show changes in surface morphology. Metallic surfaces did not show surface modifications but we found changes in the reflectivity of coated polyimide sheets, like used in Multi Layer Insulation blankets, during and after proton irradiation. Our results show that space materials exhibit significant changes after irradiation equivalent to the dose accumulated after 100 years in LEO. This knowledge is highly relevant for the interpretation of optical data related to the observation of space debris as well as to studies about laser-matter interaction for laser-based debris removal.