The Call for proposals for Earth Explorer 10 (EE-10) core mission ideas was released in September 2017. Three candidate mission ideas: Daedalus, Harmony and Hydroterra (formerly STEREOID:(Stereo Thermo-Optically Enhanced Radar for Earth, Ocean, Ice, and land Dynamics ) were selected for Phase 0 pre-feasibility study in September 2018. After completion of Phase 0 in February 2021, Harmony was selected to proceed to Phase A feasibility study. Upon successful conclusion of the feasibility study and presentation of the Harmony mission at ESA-ESTEC on 5 July 2022 at a User Consultation Meeting, Harmony was ultimately selected as Earth Explorer 10 in September 2022.
