BISOU's preliminary thermal architecture

In 30 seconds

BISOU utilizes a balloon-borne cryogenic Fourier Transform Spectrometer to measure Cosmic Microwave Background spectral distortions with extreme sensitivity. The mission architecture features a specialized thermal design, cooling four focal plane units to 100 mK while maintaining an optical bench at 2.5 K via a liquid helium cryostat. This stable, low-temperature environment is essential for minimizing instrumental emission and ensuring the accuracy of spectral reconstruction during long-duration stratospheric flights.