Title: The Stratospheric Aerosol and Gas Experiment IV (SAGE IV) Pathfinder System
Presenting Author: Charles Hill
Organization: NASA Langley Research Center
Co-Author(s): Robert Damadeo and Michael Obland

Atmospheric aerosols and ozone are designated as observing system priorities in the 2017 Decadal Survey Report (ESAS 2017). Accurate records of stratospheric aerosols are a vital piece of the puzzle regarding climate change. Stratospheric ozone has been the subject of observation and research for decades. Its importance is exhibited in the Clean Air Act, which mandates that NASA monitor atmospheric ozone. Measurements from satellites provided data on the initial decline of ozone in the late 1970s and early 1980s that supported the adoption of the Montreal Protocol, and current observations hint at a potential recovery. Adequate determination of that recovery requires continuous and, in the case of multiple instruments, overlapping data records. With SAGE III ISS currently entering its third year on orbit and with most other current ozone monitoring orbital systems well beyond their expected lifetimes, we look towards the future of satellite observations of stratospheric ozone and aerosols to develop the Stratospheric Aerosol and Gas Experiment (SAGE) IV Pathfinder. Enabled by the Instrument Incubator Program and entering Project Year 3, the SAGE IV Pathfinder team is developing and validating a technology demonstration that will pave the way for a future SAGE IV spaceflight mission. Utilizing solar occultation imaging, SAGE IV will be capable of measuring ozone, aerosol, and other trace gas species with the same quality as previous SAGE instruments but with greatly improved pointing knowledge. Furthermore, current technological advancements allow SAGE IV to fit within a CubeSat framework and make use of commercial hardware, significantly reducing the size and cost when compared with traditional missions and enabling sustainability of future measurements. SAGE IV will meet the definition of the newly-recommended Venture-Continuity missions by "bringing forward innovative approaches to sustain measurements at lower costs".