A joint European and Japanese mission to observe the vertical profiles of aerosols, and liquid water and ice, and to retrieve profiles of atmospheric radiative heating and cooling. The European Space Agency (ESA) provides the spacecraft, three instruments, and the launch; the Japan Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT) provide one instrument. ESA and JAXA provide the ground segment. The mission is planned for launch in August 2019.