CloudSat was a NASA-led Earth-observation program conducted with Canada to build a global, three-dimensional record of cloud vertical structure and cloud water. Launched on 28 April 2006, it introduced the first spaceborne 94-GHz Cloud Profiling Radar and operated in the A-Train with CALIPSO to improve understanding of clouds, climate, weather, and the water cycle. NASA ended CloudSat science operations and decommissioned the mission in December 2023.