Sustainable Spacefaring: Exploration of scrap metal powder metallurgy on the lunar surface
The increasing threat of orbital debris to the future of a safe space environment necessitates immediate action to develop sustainable end-of-life methodologies in the initial design phases. Currently, orbital spacecraft are designed-for-demise, reentering Earth’s atmosphere. This not only poses a major threat to both ground and space safety, but also leads to both an economical and environmental discussion of the sustainability of spaceflight. A circular economy in space seeks to establish reuse and recycle practices to enhance safety, save costs, and reduce the dependence on Earth resources. This thesis assesses the opportunities and limitations of upcycling scrap metal from Low Earth Orbit (LEO) as Additive Manufacturing (AM) feedstock for the lunar surface with the goal of exploring the lunar architectural surface needs for a powder metallurgy processing facility and recommend areas of improvement for the design of future spacecraft to ease the proposed recycling process. While metals can be extracted from the lunar surface, the operation of excavation, separation, processing, and extraction are energy intensive, and the actual quality of the final metal product is unknown at this time. Further, once a metal product has been manufactured on the moon, there are no recycling processes put it place after use. The development of a metal recycling system on the lunar surface is not intended to replace In-situ Resource Utilization (ISRU) initiatives, but rather, is meant to close the loop on a circular economy in space for metals. Upper stage rocket bodies are identified as one of the most dangerous debris in orbit, mostly because of the potential for residual fuel to explode. Given the mass, frequency of use, relative simplicity of design and structure compared with the intricacies of satellites, and material composition, upper stage rocket bodies are the targeted scrap metal source for this thesis. The supporting architectures include a space tug with lunar landing capabilities, a robotic crane with friction milling capabilities, and a mobile metal powder processing facility.