An Atom-Interferometer Spacecraft in Solar Orbit Measuring Inertial Phase Along a Long Quiet Baseline

This paper presents a space mission design, computed from stated assumptions and not measured, built to measure one quantity: the interferometer phase attributed to a torsion-coupled inertial effect, for which the design case adopts 0.22 radians of phase. The instrument is a single drag-free spacecraft carrying a dual-species rubidium-caesium atom interferometer with a ten-second interrogation time, laser-cooled atom sources, and a magnetic shield that holds the field at the atom cloud below the budgeted level throughout the measurement cycle. It operates from a heliocentric orbit at 0.85 astronomical units with the spacecraft in free fall throughout for 3 years. The one-day measurement uncertainty is 0.65 radians; averaged over the full mission of 1096 days it falls to 0.0196 radians, giving a signal-to-noise ratio of 11.2 for the design case and a five-sigma detection limit of 0.0982 radians. The spacecraft has a dry mass of 620 kilograms, a wet mass of 770 kilograms including propellant, and a total electrical load of 999 watts supplied by a solar array of 2.08 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.