The inertial navigation market has a need for accelerometers with high sensitivity, low noise, low cost and low power consumption. ESA has identified high accuracy accelerometer units as a priority in a 2019 roadmap. The current state of art products are not able to deliver. Here we introduce a novel accelerometer design, using concepts originally developed for gravitational wave detector physics, which will enable an accelerometer to meet these requirements. This technology drives down power consumption and cost without compromising on performance metrics. The proposed activities will develop a high performance closed loop accelerometer and read-out electronics prototype to demonstrate and validate use in space applications. The aim is to significantly improve the navigational capabilities of spacecraft and reduce the need to use other systems for orbit determination. Orbit maintenance in constellations will benefit as manoeuvres can be performed more accurately. Reduced propellant consumption will make onboard resources last longer, resulting in extended operational lifetime and a more cost-effective deployment. We are developing an ultra-sensitive microelectromechanical system (MEMS) based accelerometer with world record sensitivity for this class of sensor. High performance is achieved by an on-chip mechanical preloading system which increases the sensitivity to acceleration by a significant factor. The stiffness reduction is independent of the proof-mass position, preserving the linear properties of the mechanics and, due to its purely mechanical realization, no additional power is consumed to achieve this sensitive state. Equivalent acceleration noise levels below 1 ng/√ Hz have been demonstrated in a 50 Hz bandwidth. Measurements and models are combined to generate accurate estimates of the bias stability which show that an Alan variance below 0.01 µg is achievable. This would provide orders of magnitude improvement over currently available devices.
