EE-11 candidate mission CAIRT: payload concepts architecture, design approach, and challenges

The Changing-Atmosphere Infrared Tomography (CAIRT) mission, selected as a candidate for ESA's Earth Explorer 11 program, aims to explore the complex coupling between atmospheric composition, circulation, and climate. Focusing on the region from the mid-troposphere to the lower thermosphere, CAIRT will provide high-resolution, near-global observations of key atmospheric constituents. This paper outlines CAIRT’s science goals, mission objectives, and observation concept based on an Infrared imaging Fourier Transform Spectrometer (FTS). It presents the current status of the payload design, detailing key requirements, trades, and the proposed baseline concepts developed by two parallel industrial consortia. The paper also discusses ongoing and planned pre-developments of critical technologies.