As the world’s space agencies look to long duration spaceflight beyond low earth orbit, engineering materials in deep space flight will endure galactic cosmic ray irradiation, of which 85% is protons. Characterization of proton irradiation damage near the threshold displacement energy is required to understand the mechanisms behind performance degradation and the fluence dependent effects of a thermalized spectrum on surface sensitive tribological characteristics. Here, tribological degradation of a space-grade molybdenum disulfide lubricant exposed to low energy (500 eV) protons is investigated as a function of fluence. A 21% increased coefficient of friction and 86% increase in wear rate is measured at 10²⁰ $\mathrm{H}/{\mathrm{m}}^2$, and 170% increased CoF and 465% increased wear rate at 3·10²³ $\mathrm{H}/{\mathrm{m}}^2$. Associated softening and decreased stiffness is measured by nanoindentation. X-ray photoelectron spectroscopy and Raman spectroscopy identify the mechanism of tribological degradation as being the preferential removal of sulfur leading to a disordered and reactive non-stoichiometric MoS_2-x surface with compromised tribological properties. Missions beyond low-earth orbit will be required to withstand GCR radiation, and it is not suggested that the density of radiation damage sustained will be acutely detrimental to MoS₂ lubricants. Still, research missions should plan to characterize the magnitude of radiation damage effects.

由于世界各国航天机构都着眼于低地球轨道以外的长时间太空飞行，深空飞行中的工程材料将承受银河系宇宙射线的照射，其中85%是质子。需要表征接近阈值位移能量的质子辐照损伤，以了解性能下降背后的机制以及热化光谱对表面敏感摩擦学特性的影响。在这里，研究了暴露于低能量 (500 eV) 质子的航天级二硫化钼润滑剂的摩擦降解作为通量的函数。摩擦系数增加 21%，磨损率增加 86%，在 10 ²⁰ $\mathrm{H}/{\mathrm{米}}^2$, 3·10 ^{23 时}CoF 增加 170%，磨损率增加 465% $\mathrm{H}/{\mathrm{米}}^2$. 通过纳米压痕测量相关的软化和刚度降低。X 射线光电子能谱和拉曼光谱将摩擦降解的机制确定为优先去除硫，导致无序和反应性的非化学计量 MoS _2-x表面具有受损的摩擦学特性。低地球轨道以外的任务将需要承受 GCR 辐射，并且认为持续的辐射损伤密度不会严重损害 MoS ₂润滑剂。尽管如此，研究任务仍应计划表征辐射损伤影响的程度。