A Fourier-Transform Spectral Observatory Measuring Microwave Background Distortions Left by a Bounce Thermal History

This paper presents a space mission design, computed from stated assumptions and not measured, built to measure one quantity: the chemical-potential distortion predicted by the bounce thermal history used as the design case, for which the design case adopts 2.20e-08 in dimensionless mu distortion. The instrument is an absolute Fourier-transform spectrometer comparing the sky against an internal blackbody calibrator held at the sky temperature, covering 30 gigahertz to 3 terahertz with detectors at 0.1 kelvin, operated from a halo orbit so the instrument views cold space continuously. It operates from a halo orbit about the Sun-Earth L2 point for 4 years. The one-day measurement uncertainty is 1.50e-07 in mu distortion; averaged over the full mission of 1461 days it falls to 3.92e-09 in mu distortion, giving a signal-to-noise ratio of 5.61 for the design case and a five-sigma detection limit of 1.96e-08 in mu distortion. The spacecraft has a dry mass of 1140 kilograms, a wet mass of 1340 kilograms including propellant, and a total electrical load of 1571 watts supplied by a solar array of 4.62 square metres at the operating distance. Every performance figure in this paper comes from the deposited computation; the design is simulated, not measured, and no hardware described here has been built or flown.