Advances in cold atom interferometer accelerometry and their impact on the sensitivity of gravity missions

Abstract

Cold Atom Interferometer (CAI) accelerometry is proposed for future generations of satellite gravimetry missions. The technique can achieve high sensitivity and provide long-term stability and precise measurements of the non-gravitational accelerations acting on the satellites. This would reduce the overall instrumental errors and improve the observation of the Earth's gravity field and its change over time and enable a better understanding of several geophysical phenomena, also related to climate change. The current CAI accelerometers have shown great performance, especially in the lower frequencies. They have been able to considerably reduce the bias which is usually seen in the measurements of conventional electrostatic accelerometers. However, noise sources such as satellite rotation can degrade the CAI solution if they are not carefully compensated. In this study, we model the most impactful error sources which perturb the measurements of a CAI accelerometer onboard a GRACE-like satellite. We further investigate the sensitivity of the instrument to the various error sources, including detection noise, aberrations of laser wavefront, contrast loss due to the Coriolis acceleration and laser intensity inhomogeneity. We also consider the potential improvements which can be expected for satellite-based CAI accelerometers in the near and far future (e.g. longer interrogation time, rotation compensation in different scenarios, and increasing the laser waist). Additionally, we study their potential benefit for future satellite missions and the retrieval of the Earth's gravity field.