Effectiveness of three microbial sterilization technologies on typical microorganisms in the AIT stage and their material compatibility

Research on efficient microbial sterilization technologies during the Assembly, Integration, and Testing (AIT) stage of spacecraft, and their compatibility with typical spacecraft materials, is crucial for advancing planetary protection technologies, especially in missions targeting Mars. In this study, a prototype integrating three microbial sterilization methods, including vapor-phase hydrogen peroxide (VHP), low-pressure cold plasma (LPCP), and the combination (VHP-LPCP), which show promise for planetary protection applications, was constructed and its reduction efficacy against typical microorganisms during the ‘assembly, integration and test (AIT)’ stage of spacecraft, specifically spore-forming bacteria, was evaluated, which is a crucial step in preventing the biological contamination of Mars with Earth-origin microbes. Additionally, the impact of these three sterilization methods on the performance of materials and electronic components which are commonly used in the aerospace industry was examined. Experimental results demonstrated that using a VHP dosage of 851.1 mg/L·s, applying LPCP at 150 W for 9.76 min, or employing a combined method with 419.4 mg/L·s VHP followed by LPCP at 150 W for 4 min, all achieved a reduction of at least four orders of magnitude in spore counts of three types of spore-forming bacteria on tested surfaces. Compatibility tests with typical spacecraft alloys, polymers, and electronic components indicated that while the sterilization treatments may alter the surface composition of some materials, they did not significantly impact the main functional characteristics of the materials and components, demonstrating promising material compatibility. This study supports the development of robust microbial sterilization technologies for planetary protection, aiding China's deep space exploration efforts, and also provides some guidance for planetary protection in future Mars exploration activities.