Practical Space Resource Utilization at the Hundred Megatonne Scale: Enabling a Planetary Sunshade to Reverse Global Warming

Climate change is the defining issue of our time. Decarbonizing Earth's economy and removing existing carbon from the atmosphere are mandatory steps for addressing climate change, but may not occur quickly enough to avoid catastrophic global warming. Space-based solar radiation management is one technique to address global warming by deflecting a small percentage of incoming solar energy before it enters Earth's ecosphere. The concept of a planetary sunshade is a physical, thin-film structure of about one million square kilometers, placed at Sun-Earth Lagrange 1, to mitigate or even reverse global warming. If the sunshade is made from space resources, it could provide a powerful objective for developing a space resources economy built on megascale construction. The planetary sunshade could require hundreds of megatonnes of material to build; this scale of space resource utilization has only barely been considered. In August of 2021, the Planetary Sunshade Foundation, in conjunction with the Colorado School of Mines, held a workshop to begin development of a space resource utilization plan with an emphasis on the scale needed to construct the sunshade. The workshop had 25 attendees, representing civil space agencies, industry, academia, and researchers from six countries. Working groups focused on resource extraction and processing and logistics for both lunar and asteroidal resources. These groups discussed the current state of knowledge, knowledge gaps, and future work required for extraction and processing techniques and logistics architectures. The purpose of this paper is to describe the key findings and conclusions of that workshop.