Design and Construction Considerations for Lunar Outpost

Engineers utilize various codes in the process of design, whether structural, mechanical, or otherwise. Reliance on a code for design is based on the knowledge that a tremendous amount of time and effort was spent by experienced engineers to codify theories and good practice in a particular design discipline. Good practice in structural design implies cognizance of materials, structural behavior, environmental loadings, assumptions made in analysis and behavior, and the uncertainties inherent in all of these. The American Institute of Steel Construction's (AISC) Manual of Steel Construction is such a codification for the design and construction of steel structures. It includes information, some tabular and the rest in the form of specifications and commentaries, necessary to design and provide for the safe erection of steel‐framed structures. The design equations are generally semiempirical, that is, they are based on a mix of theoretical analysis, experimental data, and factors of safety. Each of these components has associated implicit assumptions. Some of these assumptions were explored to understand how and if the Earth‐based design code could be used for the design of a lunar outpost. Topics discussed come from the AISC Code of Standard Practice and the commentaries, and issues such as scaling of loads and strength in the 1∕6 g lunar environment, thermal cycling effects and fatigue, stiffening and buckling are briefly discussed. Important topics for further detailed study include: (1) The relationships between severe lunar temperature cycles and fatigue; (2) very low temperature effects and the possibility of brittle fractures; (3) outgassing for exposed steels and other effects of high vacuum on steel∕alloys; (4) factors of safety originally developed to account for uncertainties in the Earth design∕construction process undoubtedly need adjustment for the lunar environment; (5) dead loads∕live loads under lunar gravity; (6) buckling∕stiffening and bracing requirements for lunar structures that will be internally pressurized; and (7) consideration of new failure modes such as high‐velocity micrometeorite impacts.