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 atmospheric wind 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 of the atmospheric backscatter signal. The analysis of the root cause was supported by the Pierre Auger Observatory in Argentina 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, but also helped to improve the accuracy in the determination of the laser beam’s ground track on single pulse level. The results presented in this paper set a precedent for the monitoring of space lasers by ground-based telescopes and open new possibilities for the calibration of cosmic-ray observatories.

中文翻译：

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空间激光器的地面观测以评估其在轨性能

欧洲航天局的风神任务是地球观测的突破性成就。2018年至2023年，风神卫星星载激光雷达仪器ALADIN测量了覆盖全球的大气风廓线，为提高数值天气预报的准确性做出了贡献。然而，由于大气反向散射信号逐渐丢失，风观测的精度在任务过程中下降。根本原因的分析得到了阿根廷皮埃尔奥格天文台的支持，该天文台的荧光探测器记录了仪器在太空中发射的紫外激光脉冲，从而提供了2019年数天内仪器出口处激光能量的估计， 2020年和2021年。激光束的重建不仅可以对风神号的性能进行独立评估，还有助于提高单脉冲水平上激光束地面轨迹确定的准确性。本文提出的结果开创了地面望远镜监测空间激光的先例，并为宇宙射线天文台的校准开辟了新的可能性。