Exploring Metal Additive Manufacturing in Martian Atmospheric Environments

In-space manufacturing is essential for achieving long-term planetary colonization, particularly on Mars, where material transport from Earth is both costly and logistically restrictive. Traditional subtractive manufacturing methods are highly equipment-, energy-, and material-intensive, making additive manufacturing (AM) a more practical and sustainable alternative for extraterrestrial production. Among various AM technologies, laser beam powder bed fusion (PBF-LB) stands out due to its exceptional versatility, precision, and capability to produce dense metallic parts with complex geometries. However, conventional PBF-LB processes rely heavily on inert argon environments to prevent oxidation and ensure high-quality part formation—conditions that are difficult to reproduce on Mars. CO2 makes up over 95% of the Martian atmosphere, meaning printing in a majority-CO2 environment is of great interest for in situ manufacturing in a Martian colonization effort. This study investigates the feasibility of using pure carbon dioxide (CO2) as a potential substitute for argon in PBF-LB manufacturing. Single-track and two-dimensional 316L stainless steel specimens were fabricated under argon, CO2, and ambient air environments with a wide range of laser parameters to evaluate the influence of atmospheric composition on surface morphology, microstructural cohesion, and oxidation behavior. The results reveal that no single parameter controls the overall part quality; rather, a balance of parameters is essential to maintain thermal equilibrium during fabrication. Although parts produced in CO2 exhibited slightly inferior surface finish, cohesion, and oxidation resistance compared to argon, they performed significantly better than those fabricated in ambient air in terms of balling effects and overall cohesion. These findings suggest that CO2-assisted PBF-LB could enable sustainable in situ manufacturing on Mars and may also serve as a cost-effective alternative shielding gas for terrestrial applications.