WHAT DOES THE MOON HAVE TO DO WITH EARTH OBSERVATIONS? KNOWING THE LEVEL OF LIGHT REFLECTED BY THE MOON TO A HIGH LEVEL OF ACCURACY WOULD PROVIDE A STANDARD REFERENCE WHICH CAN BE USED TO CALIBRATE EARTH-ORBITING PASSIVE SENSORS THAT ARE USED TO MAKE HIGHLY ACCURATE MEASUREMENTS OF THE EARTH. AN ESSENTIAL CLIMATE VARIABLE MEASURED FROM SPACE THAT NOTABLY REQUIRES A HIGHLY ACCURATE REFERENCE IS OCEAN COLOR WHICH IS THE RADIOMETRY OF THE SUBSURFACE OCEAN AT WAVELENGTHS IN THE VISIBLE RANGE OF THE LIGHT SPECTRUM. OCEAN COLOR PROVIDES VITAL INFORMATION ABOUT ECOSYSTEMS BIOGEOCHEMICAL PROCESSES AND WATER QUALITY IN THE UPPER LAYERS OF THE OCEAN AND OTHER WATER BODIES AND IS IMPORTANT TO THE CARBON CYCLE AND ECOSYSTEMS FOCUS AREA. IT IS ALSO A NASA OBJECTIVE TO MAINTAIN A LONG-TERM DATA RECORD OF OCEAN COLOR SPANNING DECADES AND MULTIPLE MISSIONS TO OBSERVE SECULAR CHANGES IN OCEAN BIOGEOCHEMICAL CYCLING AND ECOLOGY IN A GLOBALLY CHANGING CLIMATE. HOWEVER OCEAN COLOR REQUIRES CALIBRATION UNCERTAINTY OF A FEW TENTHS OF A PERCENT IN ORDER TO PRODUCE SCIENCE QUALITY DATA PRODUCTS [TURPIE ET AL. 2009] AND SMALL ERRORS CAN LEAD TO SYSTEMATIC EFFECTS THAT COULD MISLEAD INTERPRETATION OF GEOPHYSICAL PROCESSES AND TRENDS IN THE OCEAN [TURPIE ET AL. 2015; TURPIE ET AL. 2014]. WE PROPOSE TO DEVELOP AN AIRBORNE MEASUREMENT CAPABILITY TO SUPPORT ACCURATE ABSOLUTE LUNAR CALIBRATION OF SPACEBORNE INSTRUMENTS MAKING EARTH MEASUREMENTS INTRODUCING THE MOON AS A STABLE CONSISTENT LONG-TERM CALIBRATION REFERENCE. LUNAR CALIBRATION HAS BEEN PROVEN VITAL TO THE QUALITY OF OCEAN COLOR DATA FROM SEAWIFS AND S-NPP VIIRS AND IS A LEVEL-1 REQUIREMENT FOR PACE AND FUTURE VIIRS MISSIONS UNDER JPSS. HOWEVER THERE ARE BIASES IN THE CURRENT LUNAR CALIBRATION REFERENCE METHODOLOGY LIMITING THE USE OF THE MOON AS AN ABSOLUTE CALIBRATION REFERENCE. INSTEAD THE METHOD COSTLY VICARIOUS CALIBRATION USING A SINGLE EARTH TARGET IS EMPLOYED FOR EACH MISSION.