| Abstract Scope |
Welding will be an enabling technology for in-space assembly and manufacturing (ISAM) and in-space repair operations, which support the burgeoning Space Economy. Prospective use cases of welding include metal repairs on long-duration lunar surface missions and assembly of large structures that do not fit within available launch vehicle envelopes – such as telecommunications arrays, tall lunar towers, and free-space transit vehicles powered by nuclear propulsion. High-energy beam welding has in-space heritage. Soviet and NASA astronauts performed electron beam welds (EBW) on orbit in the late-1960s through mid-1980s and US & Canadian scientists investigated laser beam welding (LBW) during parabolic flights in the early-1990s. The recent in-space economy boom has reignited the need for continued development of EBW and LBW processes, which are desirable for their compactness, low mass, low power consumption, and high wall plug efficiency. No space-based manufacturing laboratory capable of demonstrating, developing, and applying welding processes exists; meanwhile, individual space-based trials are expensive to develop and fly. Thus, in-space welding technology development is proceeding with computational and physics-based models in tandem with ground-based experiments. These computational and ground-based efforts will complement and drive the selection of instrumentation for planned parabolic and suborbital flights. First, a thermal model of Skylab EBW experiments is established and compared to empirical data. Next, the model is used to show variation between ground-based and in-space weld structure and properties through exploration of key variables that define the on-orbit and lunar surface space environments, namely temperature (40 – 400 K), pressure (1E-10 to 1E4 Pa), and gravity (1E-6 g to 1 g). Finally, physical processes associated with heat and mass transport during welding are evaluated through case studies across these ranges, demonstrating need for further research. |