Advanced Nanocomposites for Exploration Extravehicular Mobility Unit (xEMU) Suits using STF-Armor™ for Lunar Regolith Dust Mitigation

Environmental protection garments (EPG) leveraging the benefits of shear thickening fluid (STF) enhanced textiles can directly address key space suit technology gaps and enable sustainable Lunar and Martian exploration missions. The addition of STF to conventional space suit textiles has been shown to provide mass-efficient enhancement of critical physical hazard protection properties, including dust mitigation, puncture, and MMOD/secondary ejecta (Cwalina et al., 2016; Dombrowski et al., 2018). Addition of approximately 9wt% of STF to conventional Orthofabric resulted in a nearly three-fold increase in puncture force. Here, we present ongoing testing and development of STF-enhanced EPG materials against low temperature and Lunar regolith simulant adhesion/penetration, culminating in the production of a demonstration prototype pair of EPG legs. A novel method was developed for evaluating interactions of Lunar highlands regolith simulants with STF-enhanced EPG shell fabrics. Quantitative estimates of dust penetration/total dust burden were obtained, as were qualitative results that demonstrated the effectiveness of the treatments for increasing dust rejection and facilitating cleaning. The dust test method is amenable to evaluating various factors of suit design vis-à-vis dust properties, including the effects of different seaming strategies and/or patterning on the potential for dust adhesion/penetration. STF treatment combined with a superhydrophobic "lotus leaf" coating facilitated removal of regolith simulant adhering to the surface of the shell fabric and significantly reduced the total dust burden (the sum of dust adhering to the fabric and dust able to penetrate through the fabric). Different seaming parameters did not have a strong effect on dust penetration, a result attributed to the fact that the face-to-back ties in the Orthofabric structure resulted in partial voids that were comparable in size to the holes created by the stitching needle. A prototype pair of leg EPGs was fabricated and delivered for NASA evaluation.