CASPA-ADM – a mission concept for observing thermospheric mass density

The objective of the Cold Atom Space Payload Atmospheric Drag Mission (CASPA-ADM) study, which is supported by ESA, is to develop a mission concept for observing thermospheric mass density with an accelerometer based on Cold Atom Interferometry (CAI) as a technology demonstrator. CAI technology has undergone rapid development in the recent years and experimental systems have been flown on the International Space Station and in sounding rockets for CAI research purposes.  Despite this, CAI has not yet been used as the fundamental sensor technology in a science mission, so CASPA-ADM would be a significant advancement.  CAI relies on cooling a vapour of atoms in a vacuum chamber close to absolute zero temperature using lasers and using the properties of the atoms to form a matter-wave interferometer that is extremely sensitive to accelerations. A key advantage over classical accelerometers is that the CAI measurements are not affected by any biases or scale factors. Transforming acceleration measurements to thermospheric density observations requires also measurements of the atmospheric composition, temperature, and wind. For that purpose, a neutral mass spectrometer and a wind sensor will be part of the scientific payload. For validation, the payload will include a multi-frequency GNSS receiver that allows to infer non-gravitational acceleration observations, albeit at much lower resolution along the orbit. All of these instruments will be built into a 16U CubeSat, which will be launched into an inclined orbit at an altitude of initially 400 km to achieve a fast sampling of local times and address the present observational gaps in thermosphere density observations. In this presentation, we will provide an overview of the mission objectives, explain the mission concept, and report the results from the ESA study.