Stratospheric Aerosol and Gas Experiment (SAGE) IV Pathfinder

The Clean Air Act mandates NASA to monitor stratospheric ozone, and stratospheric aerosol measurements are vital to our understanding of climate.  Maintaining reliable long-term measurements will require increasing access to and reducing the cost of frequent spaceborne missions.  However, the best measurements have been and continue to be delivered via expensive, single instruments (e.g., SAGE II, SAGE III M3M, and SAGE III ISS launched in 2017) deployed onboard large, heavy platforms.  Instead, a constellation of relatively inexpensive SAGE IV sensorcraft can maintain the stratospheric ozone record and provide critical measurements of stratospheric aerosol and other trace gases.

A solar occultation imager in a small form factor can provide high-quality science at a small fraction of the cost and even improve data quality in the upper troposphere / lower stratosphere.  The imaging technique intrinsically eliminates all of the major technological and algorithmic challenges of previous solar occultation instruments, yet to date there has not been a radiometric solar occultation imager.  The SAGE IV system design enables continuous on-orbit characterization of instrument behavior and performance.  The majority of hardware is commercially available, and the entire payload can fit inside a 6U CubeSat.  Current technology limits telemetered data volume from a CubeSat, but embedded control algorithms will be developed to ensure all raw science data is retained and transmitted.

The SAGE IV Pathfinder started out as an Internal Research and Development (IRAD) project at NASA Langley Research Center in Hampton, Virginia and was successfully infused into the NASA Instrument Incubator Program (IIP) under the NASA Earth Science Technology Office.  Under IRAD, detailed design and analysis were performed to ensure viability and future success of the instrument and mission concepts.  The SAGE IV Pathfinder IIP will build and test a ground demonstration unit over the next three years and is the first stepping stone to a future on-orbit mission.