Atom-based quantum gravity gradiometry (QGG) provides a transformative capability for achieving the time-variable gravity and mass change observation goals specified in the 2017 Earth Science Decadal recommendations. This technique utilizes electromagnetically cooled atoms within an ultra-high-vacuum enclosure, which are manipulated into a quantum superposition state via optical fields and subjected to free fall. The resulting cold-atom interference patterns are a function of local gravitational and non-inertial accelerations, interaction time, and the phases of the manipulating optical fields. By employing two atom-interferometric sensors separated by a baseline on a single platform and driven by a common interferometry laser, the system eliminates most common-mode noise and achieves high sensitivity to relative differences in gravitational acceleration. Such sensitivity could enable single-satellite orbital sensors to improve upon the performance of the Gravity Recovery and Climate Experiment (GRACE) and GRACE-FO missions—which rely on satellite-satellite tracking (SST)—by an order of magnitude.
Building upon its sponsorship of several terrestrial prototype instruments and studies to better understand the fundamental physics and technical challenges of developing a QGG for Earth observation missions, ESTO is supporting the Quantum Gravity Gradiometer Pathfinder (QGGPf) mission. The QGGPf seeks to demonstrate relevant gravity gradient sensitivity in a low-Earth-orbit (LEO) environment, advance U.S. industrial capabilities in quantum instrumentation, and reduce risk for future Science Grade Instruments (SGI). Key technical objectives include producing interferometric fringes in space with parameters not achievable on the ground, deriving gravity gradients for geodetic interpretation, and implementing a reliable, tunable physics protocol within a noise-mitigated spacecraft environment. This presentation will provide a high-level overview of the QGGPf mission, including the notional instrument configuration, physics protocol, concept of operations, driving requirements, and error budget.
This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004).