## 2 Materials and Methods
### Outpost Construction Techniques
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Reference** & **Year** & **S, U, H \({}^{*}\)** & **Construction Technique** & **Material Type** & **Analysis Method** \\ \hline
[14] & 1992 & H & Flat truss & Lightweight Truss and regolith cover & Static \\ \hline
[13] & 1992 & S & Inflatable & Kevlar 49 and regolith cover & Static and numerical \\ \hline
[15] & 1993 & S & Tensegrity & Unmentioned & Unmentioned \\ \hline
[58] & 1993 & S & Inflatable & Kevlar 49 and regolith cover & Static and numerical \\ \hline
[59] & 1994 & H & Flat truss & Composite Truss and regolith cover & Static \\ \hline
[69] & 1995 & H & Flat truss & Aluminum Truss and regolith cover &
\begin{tabular}{c} Static, Dynamic, and \\ numerical A \\ \end{tabular} \\ \hline
[60] & 1996 & S & Inflatable & Kevlar and regolith cover & Static and numerical \\ \hline
[70] & 1999 & S & Inflatable & Kevlar & Static \\ \hline
[71] & 2000 & S & Inflatable & Kevlar & Static and numerical \\ \hline
[72] & 2004 & S & Inflatable & Kevlar & Static \\ \hline
[73] & 2004 & S & Inflatable & Kevlar & Static \\ \hline
[74] & 2006 & S & Inflatable & Kevlar & Static \\ \hline
[17] & 2006 & S & Deployable & laminates of AS4 Carbon PEEK &
\begin{tabular}{c} Dynamic and \\ numerical \\ \end{tabular} \\ \hline
[75] & 2006 & variable & Deployable and inflatable & Variable (review paper) & Not applicable \\ \hline
[18] & 2006 & H & Arch & Aluminum & Numerical A \\ \hline
[19] & 2006 & H & Arch & Aluminum & Numerical A \\ \hline
[23] & 2006 & S & Truss and inflatable &
\begin{tabular}{c} Truss made of aluminum; inflatable \\ structure made of Kevlar \\ \end{tabular} & Numerical A \\ \hline
[24] & 2008 & S & Truss and inflatable &
\begin{tabular}{c} Truss made of aluminum; inflatable \\ structure made of Kevlar \\ \end{tabular} & Dynamic \\ \hline
[68] & 2007 & S & Arch & Regolith-based sulfur concrete & Static and thermal \\ \hline
[76] & 2010 & S & Arch & Regolith-derived voussoir dome & Static \\ \hline
[21] & 2012 & S & 3D printing & Sintered regolith and sulfur concrete & Not applicable \\ \hline
[25] & 2013 & S & Truss and inflatable &
\begin{tabular}{c} Truss made of aluminum; inflatable \\ structure made of Kevlar \\ \end{tabular} & Numerical \\ \hline
[20] & 2014 & S & 3D Printing and inflatable & Regolith & Numerical \\ \hline
[38] & 2017 & U & Tunnel & Precast lining & Numerical \\ \hline
[77] & 2018 & S & Deployable & Mylar &
\begin{tabular}{c} Numerical, empirical \\ approaches \\ \end{tabular} \\ \hline
[39] & 2018 & U &
\begin{tabular}{c} Lunar/Martian lava tubes \\ \end{tabular} & - & Static and numerical \\ \hline
[78] & 2018 & S & Inflatable & ETFE membrane/Kevlar network & Numerical \\ \hline
[79] & 2019 & S & 3D Printing & Sintered regolith &
\begin{tabular}{c} Destructive \\ mechanical tests \\ \end{tabular} \\ \hline \hline \end{tabular} \({}^{*}\)(U = underground; S = surficial; H = hybrid).  
\end{table} 
Table 1: Chronological order of major proposed extra-terrestrial outpost designs. Inflatable structures provide high tensional and compressional strength values, which are the most crucial properties in extraterrestrial structural design. It can be said that from 1992 until now, the most proposed structures are based on inflatable structures. In most, the material of the inflatable structure has comprised Kevlar (reinforced carbon composite) membranes [13; 58; 60; 73; 74; 78]. Yet, the popularity of inflatable structures has exponentially continued to grow amongst outpost designers and architects. Moreover, 3D-printed outposts need an inflatable module to form an internal breathable environment [20]. Figure 5 (Left) shows interconnected structural modules made of inflatable modules and a 3D-printed protective regolith layer. Not only for lunar and Martian outpost construction, but regolith has also been proposed for building habitats on the International Space Station [70; 71] and in low Earth orbit [72]. Figure 5 (Right) depicts the TransHab designation proposed by [PERSON] [70].