Ground observations of a space laser for the assessment of its in-orbit performance

THE PIERRE AUGER COLLABORATION (A. ABDUL HALIM, ..., A.D. SUPANITSKY, ...)

Optica

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Año: 2024 vol. 11

The wind mission Aeolus of the European Space Agency was a groundbreaking achievement for Earth observation.Between 2018 and 2023, the space-borne lidar instrument ALADIN onboard the Aeolus satellite measured atmosphericwind profiles with global coverage, which contributed to improving the accuracy of numerical weather prediction.The precision of the wind observations, however, declined over the course of the mission due to a progressive loss ofthe atmospheric backscatter signal. The analysis of the root cause was supported by the Pierre Auger Observatory inArgentina whose fluorescence detector registered the ultraviolet laser pulses emitted from the instrument in space,thereby offering an estimation of the laser energy at the exit of the instrument for several days in 2019, 2020, and 2021.The reconstruction of the laser beam not only allowed for an independent assessment of the Aeolus performance, butalso helped to improve the accuracy in the determination of the laser beam’s ground track on single pulse level. Theresults presented in this paper set a precedent for the monitoring of space lasers by ground-based telescopes and opennew possibilities for the calibration of cosmic-ray observatories.