Dr. Johnson is recognized for initiating a collaboration in 1995 with the NASA Earth Observing System program that she continues today with all three U.S. civilian space agencies (NASA, NOAA, and USGS) to provide the radiometric metrology, standards, calibration-plan review, and quality assurance to establish and maintain the SI traceability of environmental satellite measurements. Such traceability is essential for detecting the small, yearly, incremental changes in environmental variables that become the signatures of significant change over decadal and longer time scales. Johnson’s efforts include prelaunch, on-orbit, and in situ vicarious calibrations that enable accurate measurements of land, ocean, and atmospheric quantities.