Improved Radiometric calibration of Imaging Systems (IRIS) for next generation small satellite imagers

Abstract

The NASA Earth Science Technology Office (ESTO) funded Improved Radiometric calibration of future land Imaging Systems (IRIS) Advanced Technology Development (ATD) is developing and demonstrating technology to simplify onboard calibration systems and reduce risk, cost, size, mass, and development time for next generation small satellite instruments, while meeting or exceeding current capabilities. IRIS addresses this objective in two different, but complementary ways. The first way involves designing and building an ultra-compact, full spectrum (0.4-2.3 µm and 4- 13 µm) end-to-end calibration source and testing this source with the existing NASA ESTO Advanced Technology Land Imaging Spectroradiometer-Prototype (ATLIS-P) built by Raytheon. IRIS extends ATLIS-P by reducing volume of the onboard calibration assembly by 90% relative to current flight systems using an innovative, full-spectrum Jones source. IRIS will demonstrate a functionally complete full-spectrum prototype land imager with much reduced size and mass by verifying calibration performance across the full spectral range and full imager field of view by comparison with well-understood NIST traceable full aperture laboratory sources. The second way involves in-flight absolute solar radiometric calibration of L8 and L9 OLI onboard lamp assemblies based on Raytheon’s patented Specular Array Calibration (SPARC) method. SPARC uses spherical convex mirrors to create a collection of “solar stars” with identical spectra and well-defined radiometric properties directly traceable to the exoatmospheric solar spectral constant. This IRIS-Vicarious (IRIS-V) aspect of the project involving SPARC site observations provides in-flight absolute calibration and image quality validation. IRIS-V intends to image a commercial SPARC site on Mauna Loa developed by Labsphere. NASA ESTO funded this work through grant 80NSSC20K1676 to Raytheon Company.