Evaluation of the Effect of Space Debris Impact on Atomic Oxygen Protectant Materials for MLI

Multi-layer insulation (MLI) generally covers the surfaces of spacecraft, and it contributes to thermal control of that. Because of the excellent heat and radiation resistance, polyimide is often used as the outermost layer of MLI. But polyimide is known to be eroded by atomic oxygen (AO) in low earth orbit. Coating a polyimide with an inorganic layer is one way to improve AO tolerance of MLI, and this method is widely used. However, inorganic layers sometimes tend to contain manufacturing defects and they also tend to be fragile, and AO erosion occurs from these areas. To solve the issue mentioned above, we have been developing AO protectant materials, polyimide itself, and coating agent for MLI with keywords of self-organization and self-healing. Self-organization is the property which generates AO-resistant layer on the surface by the material itself with AO irradiation. In addition, if the AO-resistant layer is damaged, the material re-generates AO-resistant layer by itself with AO irradiation again. We call this property as self-healing. Our materials have been studied in orbital exposure experiments and self-organization property of our materials have been demonstrated. In addition, we demonstrated that our materials have self-healing property in ground test.<br/>However, we haven’t known that whether our materials maintain self-organization and self-healing properties after collision with space debris. It is known that collision with debris occurs high heat, high strain rate etc. and some materials break in different destruction mode compared with that on the ground.<br/>Therefore, it is necessary to evaluate whether our materials have the same self-organization and self-healing properties after collision with debris and we conducted a series of the ground test. In this presentation, we will report our plans and experimental results obtained to date.