[Paper Review] Towards a realistic noise modelling of quantum sensors for future satellite gravity missions

J. Encarnação, Christian Siemes+5 more|arXiv (Cornell University)|Apr 11, 2024

Solar and Space Plasma Dynamics4 citations

TL;DR

This paper develops realistic noise models for cold atom interferometry (CAI) sensors in future satellite gravity missions, analyzing how satellite attitude errors affect Coriolis accelerations. It compares concurrent and sequential operation modes, showing sequential mode reduces attitude-related errors by starting with zero-velocity atom clouds, significantly improving low-frequency gravity gradient measurement accuracy.

ABSTRACT

Mapping the Earth's gravity field from space offers valuable insights into climate change, hydro- and biosphere evolution, and seismic activity. Current satellite gravimetry missions have demonstrated the utility of gravity data in understanding global mass transport phenomena, climate dynamics, and geological processes. However, state-of-the-art measurement techniques face noise and long-term drift limitations, which propagate into the recovery of Earth's time-varying gravity field. Quantum sensors, particularly Cold Atom Interferometry (CAI), offer promise for improving the accuracy and stability of space-based gravity measurements. Therefore, CAI has emerged as a promising measurement technique for future gravimetric satellite missions due to their potential for measuring gravitational forces and gradients with high precision and accuracy, particularly at low frequencies (sub-mHz). This study explores the sensitivity of CAI accelerometers and gradiometers to the errors in measuring the satellite's attitude. We explore the low-low satellite-to-satellite and gravity gradiometry concepts and build the respective analytical models of measurements and associated errors. We selected an ambitious scenario for CAI parameters that illustrates a potential path for increasing instrument accuracies and capabilities for space gravimetry. Two operational modes, concurrent (where a new cloud is generated while another is moved to the interferometric chamber) and sequential (where cloud generation and interferometry happen in the same place), are compared to mitigate the effects of inaccurately known attitude rates on Coriolis accelerations. The sequential mode shows the potential to reduce these effects since the atom cloud has an initial zero velocity. [...]

Motivation & Objective

• To assess the impact of satellite attitude errors on cold atom interferometer (CAI) measurements in space-based gravity missions.
• To model noise sources arising from inaccurately known attitude rates, particularly Coriolis accelerations.
• To compare concurrent and sequential operation modes of CAI for mitigating attitude-induced errors.
• To evaluate the potential of CAI for high-precision, low-frequency gravity gradient measurements in future missions.
• To provide a foundation for realistic instrument performance modeling in upcoming Earth observation satellite missions.

Proposed method

• Developed analytical models for low-low satellite-to-satellite tracking and gravity gradiometry using CAI sensors.
• Formulated error propagation models for attitude rate inaccuracies, focusing on Coriolis acceleration effects on atom interferometry.
• Simulated two operational modes: concurrent (simultaneous cloud generation and interferometry) and sequential (sequential cloud generation and interferometry in one location).
• Quantified the influence of initial atom cloud velocity on Coriolis error sensitivity, favoring zero-initial-velocity conditions.
• Used a high-performance CAI parameter scenario to project achievable noise levels and error suppression.
• Evaluated the sensitivity of accelerometers and gradiometers to attitude errors under realistic mission constraints.

Experimental results

Research questions

• RQ1 How do inaccurately known satellite attitude rates affect Coriolis accelerations in cold atom interferometers?
• RQ2 What is the relative performance of concurrent versus sequential operation modes in suppressing attitude-induced errors?
• RQ3 To what extent can sequential operation reduce Coriolis errors by enabling zero-initial-velocity atom clouds?
• RQ4 What level of noise reduction can be achieved in low-frequency gravity gradient measurements using realistic CAI modeling?
• RQ5 How do CAI sensor parameters influence the feasibility of future satellite gravity missions?

Key findings

• Sequential operation mode significantly reduces Coriolis acceleration errors by starting with zero initial velocity of the atom cloud.
• The sequential mode suppresses attitude-induced noise more effectively than the concurrent mode due to better control over initial conditions.
• Realistic noise modeling reveals that attitude rate errors are a dominant source of low-frequency noise in CAI-based gravity gradiometers.
• The study demonstrates that with optimized CAI parameters, sub-mHz gravity gradient measurements can achieve high precision.
• The analytical models provide a framework for predicting instrument performance under realistic mission conditions, supporting future mission design.