Author

Jacob Yates

Date of Award

December 2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Aerospace Sciences

First Advisor

James Casler

Abstract

In-situ materials provided adequate shielding against the risk of meteorite ejecta for future lunar surface operations. Both regolith simulant and simulant-epoxy mixtures stopped simulated ejecta projectiles with velocities at or near lunar escape velocity. Those depth penetrations for those two in-situ related materials were shallow inside 3 cm and may prove to be influential in future mission planning of lunar surface operations. The lunar surface poses a potential risk from meteoroid ejecta for future lunar surface operations. The safety ramifications of long-term crewed missions for the Artemis program, NASA’s lunar program, are being investigated or reconsidered from the previous Apollo program. Recent studies observed ejecta debris from meteoroid impacts, traversing over greater distances than originally postulated in this current geological epoch. Two end-member ejecta types that are the most hazardous are: (1) iron lithic fragments, and (2) impact feldspar spheres. A series of hypervelocity impact tests using a two-stage light gas gun (2SLGG) was conducted against a set of proposed materials that are likely to be used for lunar surface operations.

The results of this study have several implications for developing protective measures against lunar ejecta traveling at hypervelocity speeds in lunar environments. The success of regolith and regolith-epoxy simulants in stopping projectiles highlights their potential for use in shielding structures and spacesuit design. Furthermore, the ability of even a single layer of EVA suit material to degrade or vaporize micrometeoroids suggests that multilayer structures could indeed offer effective protection against such lunar hazards. Conversely, the failure of materials like aluminosilicate glass, aerogel, and space shuttle tiles underscores the need for more robust solutions for larger, higher-energy impacts. Additional research should focus on optimizing material properties with in-situ regolith, designing or incorporating layered structures such a Whipple-shields to enhance impact resistance. These findings can inform the development of more reliable protective measures for lunar landing spacecraft, lunar habitats, and spacesuits, thereby ensuring the safety of future lunar missions.

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