Abstract
The Atmospheric Waves Experiment (AWE) utilizes the Advanced Mesospheric Temperature Mapper (AMTM), built by the Space Dynamics Laboratory (SDL) and mounted on the International Space Station (ISS), to observe OH airglow emissions at approximately 87 km altitude, enabling the study of gravity wave dynamics in the mesosphere. A critical component of AWE data processing is the geolocation algorithm, which determines the latitude and longitude coordinates where each pixel’s line-of-sight (LOS) vector intersects the Earth’s atmosphere. This algorithm is essential for producing accurate data products for the corresponding spatial radiance swaths generated by the science team at Utah State University (USU). The algorithm employs a series of transformations between the AMTM, ISS, Earth-Centered Inertial (ECI), and Earth-Centered Earth-Fixed (ECEF) coordinate systems. These conversions rely on ISS position, velocity, and attitude data, which are interpolated to match AMTM image timestamps. Interpolation is performed using linear and spherical linear interpolation (SLERP) depending on the magnitude of attitude changes between samples. To refine the rotation matrix between the AMTM and ISS coordinate systems, an on-orbit calibration process is implemented using ground-truth tie points. An iterative adjustment minimizes residuals between observed and predicted locations, optimizing the geolocation accuracy of the AMTM imagery. An additional set of tie points are set aside for validating the accuracy of the geolocation process after the on-orbit calibration. These tie points show position deviations well within program requirements for the AMTM’s ~0.35° instantaneous field-of-view (IFOV) and 2 km pixel resolution at ~420 km orbit altitude. This ensures robust SDL geolocation support for the NASA-funded AWE mission to investigate atmospheric wave structures and their global propagation characteristics.
Geolocation Algorithms and On-Orbit Calibration for Atmospheric Waves Experiment
The Atmospheric Waves Experiment (AWE) utilizes the Advanced Mesospheric Temperature Mapper (AMTM), built by the Space Dynamics Laboratory (SDL) and mounted on the International Space Station (ISS), to observe OH airglow emissions at approximately 87 km altitude, enabling the study of gravity wave dynamics in the mesosphere. A critical component of AWE data processing is the geolocation algorithm, which determines the latitude and longitude coordinates where each pixel’s line-of-sight (LOS) vector intersects the Earth’s atmosphere. This algorithm is essential for producing accurate data products for the corresponding spatial radiance swaths generated by the science team at Utah State University (USU). The algorithm employs a series of transformations between the AMTM, ISS, Earth-Centered Inertial (ECI), and Earth-Centered Earth-Fixed (ECEF) coordinate systems. These conversions rely on ISS position, velocity, and attitude data, which are interpolated to match AMTM image timestamps. Interpolation is performed using linear and spherical linear interpolation (SLERP) depending on the magnitude of attitude changes between samples. To refine the rotation matrix between the AMTM and ISS coordinate systems, an on-orbit calibration process is implemented using ground-truth tie points. An iterative adjustment minimizes residuals between observed and predicted locations, optimizing the geolocation accuracy of the AMTM imagery. An additional set of tie points are set aside for validating the accuracy of the geolocation process after the on-orbit calibration. These tie points show position deviations well within program requirements for the AMTM’s ~0.35° instantaneous field-of-view (IFOV) and 2 km pixel resolution at ~420 km orbit altitude. This ensures robust SDL geolocation support for the NASA-funded AWE mission to investigate atmospheric wave structures and their global propagation characteristics.