Fig. 1. Illustration of TRUTHS mission (this figure comes from Traceable Radiometry Underpinning Terrestrial- and Helio- Studies (TRUTHS)—a ‘gold standard’ imaging spectrometer in space to support climate emergency research)

Fig. 2. Illustration of on-orbit traceability chain for the TRUTHS mission (this figure comes from https:∥www.npl.co.uk/earth-observation/truths/satellite-calibration)

Fig. 3. Schematic representation of the CLARREO Pathfinder project (this figure comes from https:∥clarreo-pathfinder.larc.nasa.gov/calibration/)

Fig. 4. Schematic representation of the independent calibration approach for CLARREO Pathfinder (this figure comes from https:∥clarreo-pathfinder.larc.nasa.gov/calibration/)

Fig. 5. Principle of radiometric benchmark payload

Fig. 6. Principle of electric substitution measurement

Fig. 7. Prototype of space cryogenic absolute radiometer

Fig. 8. Modal analysis of space cryogenic absolute radiometer

Fig. 9. Lightpath of Earth-Moon hyperspectral imager

Fig. 10. Residual LPS under different wavebands with angle of wedge to be 0.81°

Fig. 11. Spectral radiance of the pupil of the hyperspectral imager with solar altitude angle of 30° and albedo of 0.3

Fig. 12. Signal-to-noise ratio of hyperspectral imager with solar altitude angle of 30° and albedo of 0.3. (a) Visible-near-infrared waveband; (b) shortwave infrared waveband

Fig. 13. Radiometric traceability chain on the on-orbit benchmark payload

Fig. 14. Optical design of solar monochromator

Fig. 15. Diameter at main stop of space cryogenic absolute radiometer

Fig. 16. Radiometric calibration diagram of the Earth-Moon imaging spectrometer traced to the national cryogenic radiometer