Investigation of carbon nanotube sheet for lunar dust shielding

Carbon nanotubes (CNT) sheet is a new type of nonwoven fabric that is being evaluated for different applications. This article presents the first friction-based investigation of the use of CNT sheet as a dust shield. The focus application is for shielding future machinery on the moon from lunar dust. Lunar dust is strongly abrasive; it adheres to all surfaces and causes wear. The absence of an atmosphere and water on the moon, along with its low gravity, and electrostatic adhesion exacerbates the issue of lunar dust, which affects all surfaces, including machinery and human apparel. Friction testing was performed to represent the effect of abrasion occurring on a garment surface while astronauts are working on the moon. The coefficients of static and sliding friction between two CNT sheets, held against each other by a weight, were 0.6 and 0.45, respectively. The presence of lunar regolith simulant reduced the friction coefficients between the two CNT sheets by 33% and 22% for static and sliding friction, respectively. The dust in the sheets was easily cleaned with dry wiping and compressed air, showing no requirement to use water for cleaning in space applications. However, the CNT sheets experienced wear after repeated friction tests. The CNT sheets passed the flammability test standards ASTM D6413/D6413M-15 and NPFA 1971 for applications under extreme heat conditions. Thus, CNT sheet can be considered as a multi-functional material for lunar applications, with shielding protection against dust and electromagnetic waves, and resistance to high temperatures.