This NASA Innovative Research Grant activity conducts engineering analysis to demonstrate the feasibility and advantages of applying a breakthrough remote sensor calibration concept to a wide range of future NASA remote sensor science missions, e.g., PACE, GEO-CAPE, CLARREO, HySpIRI, GACM and Heliophysics research.
Our concept, currently a TRL-2 mature aerospace subsystem for use with space-based, remote sensors, improves radiometric measurement accuracy in the ultraviolet, visible and near infrared (UV/VIS/NIR) bands over current technology by a factor of 10. Our International Standard (SI) calibration concept is spectrally resolved, permitting very small changes to be detected at specific wavelengths over the continuum. The proposed concept enables future scientific and climate-class remote sensors to achieve the very low measurement uncertainty needed to accurately trend the earth radiation balance and to isolate cause/effect through highly accurate, spectrally resolved measurements in the UV/VIS/NIR from space. Such a breakthrough in remote sensor measurement accuracy is needed to obtain reliable measurements from space capable of trending decade long changes in earth climate and then associating those observed changes with root cause.
Our concept overcomes prior obstacles in replicating laboratory grade calibration in the space environment for decade long unattended operation. We intend to meet this objective by bringing the calibration accuracy of NIST into space through the unique combination of the following components: an un-cooled, broadband, Active Cavity Radiometer (ACR); a white light source; an integrating sphere; a bank of multi-color light emitting diodes and a UV/VIS/NIR Fourier Transform Spectrometer (FTS). The integrating sphere and LED sources combine with the ACR to become an on-orbit, International Radiance Standard (SI) to track and correct degradations of the primary white light calibration sources carried on the satellite. When combined with an FTS, this suite of flight hardware becomes a generic, highly accurate (~0.1%), spectrally resolved UV/VIS/NIR calibration subsystem.