From 2014 to 2018 NOAA sponsored the NOAA Satellite Observing Systems Architecture (NSOSA) program, a comprehensive study of alternative approaches to environmental observation satellites to follow-on to the GOES-R and JPSS family. This study examined the widest possible range of alternatives, from legacy continuation to radical alternatives that would restructure both the technical and business architectures. This talk will describe the application of systems architecture and engineering methods to a large study of this type. We will cover broad study of the problem area, including stakeholder analysis, formulation of an observation-based value model, generation of diverse sensing and platform alternatives, and cost-benefit assessment from multiple stakeholder perspectives. Finally, we will discuss how the study has been applied and lessons for other analyses of alternatives.