ESA Earth Explorer 11 candidate selected in November 2023 for further development, CAIRT (Changing-Atmosphere Infrared Tomography) would observe atmospheric composition and circulation from about 5 to 115 km with an imaging Fourier-transform infrared limb sounder. ESA selected WIVERN for Earth Explorer 11 implementation in September 2025 but encouraged continued CAIRT scientific studies and field campaigns for possible future implementation.