A high-precision onboard radiometric calibration method based on cooperative light sources

Traditional radiometric calibration methods for spaceborne optical remote sensors rely on ground calibration fields, natural light sources such as the moon or stars, and onboard calibration mechanisms. These methods suffer from problems such as short calibration time windows, spatial-temporal inconsistencies during the calibration process, and limited calibration frequencies. This paper innovatively proposes an on-orbit real-time radiometric calibration method based on a cooperative light source in the very low Earth orbit (300 km). By constructing a cooperative satellite system equipped with a tunable laser source, an active reference light source with precise spectral radiation characteristics is established. Moreover, the advantages of the low Earth orbit significantly reduce the effects of aerosol scattering and water vapor absorption. A spatio-temporal synchronization model between the light source and the remote sensing satellite is established, and key indicators such as the light source power and tracking and pointing accuracy are quantitatively analyzed through simulations. The cooperative light source system can support the remote sensing satellite to complete real-time calibration within minutes at any transit time period by dynamically modulating the output light intensity. Under typical Earth observation scenarios, the error of radiometric reference transfer is less than 3%. This method provides all-weather autonomous calibration capabilities for high-frequency quantitative applications such as agricultural dynamic monitoring and disaster emergency remote sensing. It significantly improves the confidence level of surface parameter inversion and has the potential for engineering applications.