The last and only measurement of the CMB spectrum was performed by COBE-FIRAS in 1991, showing that it is close to a perfect blackbody emission. However, deviations referred to as CMB spectral distortions are expected. Due to its limited sensitivity, FIRAS could only give upper limits, leading to new space missions being proposed to perform this measurement. The balloon-borne mission BISOU...
I will present the current status of the LiteBIRD JAXA mission, after it entered in reformation period since September 2024, and recently went through a key review at JAXA in September 2025.
The proposal to build a high-frequency Small Aperture Telescope (SAT) as a new component of the Simons Observatory has gained increasing momentum over the recent years. This initiative, named KAIROS, is under evaluation for funding through the CNRS RI² program (“Recherche à risque et à impact”), with the backing of three CNRS institutes: IN2P3, INSU, and INP.
KAIROS aims to deploy a focal...