Subcategory: Materials Science
Jacob Parks - University of Memphis
One of the major challenges to planetary exploration is the adhesion of regolith onto critical spacecraft equipment. Regolith can cause serious problems such as degradation of mechanical equipment, decreased solar panel efficiency, and danger to astronauts. Adhesion of regolith is caused by two main factors, electrostatic and Van der Waals forces. Issues with regolith adhesion have been reported on Mars and lunar missions, but Martian regolith is particularly problematic due to triboelectric charging during Mars planet-wide dust storms. One material on which Regolith adhesion has not been researched extensively is aerogels. Aerogels are a porous class of materials with an array of interesting properties such as low thermal conductivity and extremely low density. These properties have led to the growing use of aerogels in space applications, including cryogenic fluid containment, thermal insulation on the Mars Rover, and high velocity particle collection on NASA’s Stardust. As aerogels gain more widespread use in space, understanding the factors which lead to adhesion will be essential to increasing the longevity of their use in space exploration. The goal of this research is to understand the mechanisms that contribute to the adhesion of JSC Mars-1 simulant regolith onto aerogel substrates, with PDMS and glass as controls. To test the hypothesis that adhesion is directly due to surface interactions between the substrates and the regolith, surface properties, namely surface roughness and surface charge, were investigated. Bulk properties, such as porosity, are assumed to indirectly affect adhesion, so they were explored as well. Measurements of surface roughness and surface charge were taken with a white light interferometry profilometer and a Kelvin probe, respectively. Dust adhesion experiments were carried out in an argon purged, low vacuum at room temperature and low humidity to try to simulate dry Martian conditions. Surface area coverage and adhesion by mass was found to be lowest on the polyurea-crosslinked aerogels. Coverage was higher on polyimide aerogels and PDMS, which have high magnitude negative surface charge. These results indicate that high magnitude negative surface charge leads to more regolith accumulation. The effects of surface roughness require further investigation. Thus, future work will focus on exploring the effects of surface roughness as well as using equipment to deposit different levels of charge to simulate the possibilities of triboelectric charging of materials in the Martian environment. Once these relationships are understood, methods to mitigate adhesion will be explored. References: Sabri, F., et al. ‘Thin film surface treatments for lowering dust adhesion on Mars Rover calibration targets.’ Advances in Space Research 41.1 (2008): 118-128. Sabri, Firouzeh, et al. ‘Effect of surface plasma treatments on the adhesion of Mars JSC 1 simulant dust to RTV 655, RTV 615, and Sylgard 184.’ PloS one 7.10 (2012): e45719.
Funder Acknowledgement(s): I thank F. Sabri as a mentor and for help in the laboratory. Funding was provided by the University of Memphis Helen Hardin Honors College and the NSF. Faculty Advisor: Firouzeh Sabri, email@example.com
Faculty Advisor: Firouzeh Sabri, firstname.lastname@example.org
Role: I performed all of the experiments associated with this research. I gathered all of the baseline and experimental data. I also synthesized Polyurea-crosslinked Aerogels and PDMS samples for this research. I also played a role in designing the experiments, with the help of my advisor. I analyzed the data with help from my advisor as well.