Performance of the laser transmitters and receiver signal evolution during the Aeolus mission from 2018 to 2023

^(a) Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institute of Atmospheric Physics, Münchener Str. 20, 82234 Oberpfaffenhofen, Germany
^(b) Deutsches Zentrum für Luft- und Raumfahrt (DLR), Remote Sensing Technology Institute, Kalkhorstweg 53, 17235 Neustrelitz, Germany
^(c) Leonardo S.p.A., Via Industria, 4, 00040 Pomezia RM, Italy
^(d) Airbus Italia S.p.A., Via dei Luxardo, 22-24, 00156 Rome, Italy
^(e) European Space Agency, European Space Research and Technology Centre (ESTEC), Keplerlaan 1, Noordwijk, NL-2201AZ, The Netherlands
^(f) European Space Agency, European Space Research Institute (ESRIN), Largo Galileo Galilei, 1, 00044 Frascati RM, Italy

Published online: 9 April 2026

Abstract

The wind mission Aeolus of the European Space Agency was a seminal achievement in Earth observation and space laser technology. During its nearly five-year lifetime, the space-borne Doppler wind lidar instrument ALADIN onboard the Aeolus satellite employed two switchable ultraviolet laser transmitters to measure atmospheric wind profiles with global coverage, contributing to improving the accuracy of numerical weather prediction. Despite the excellent performance of the nominal and redundant laser which was optimized during the mission through thermal adjustments, the atmospheric return signal levels declined between 2019 and 2022 due to decreasing transmission of the optics between the redundant laser and the telescope. The root cause analysis of the signal loss 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 independent measurement of the laser energy.