Ultra-high performance gyroscopes for future X-ray interferometer missions

X-ray interferometry holds the potential to image astronomical objects with unprecedented, microarcsecond (μas) resolution, where 1 μas corresponds to 4.8 prad. This target resolution imposes extreme requirements for the accuracy of the spacecraft‘s attitude measurement when operating the X-ray interferometer.Typically, the orientation of the spacecraft is measured using three single-axis gyroscopes that measure the Euler angles (yaw, pitch and roll) in a spacecraft-fixed coordinate frame. These measurements can be complemented by a star tracker as an absolute reference. Gyroscopes that are capable of determining the orientation with the required accuracy and stability needs to outperform the current high-performance navigation-grade gyroscopes by several orders of magnitude.High-accuracy rotation angle and rotation rate measurements become increasingly important in many scientific fields: (1) Seismologists want to observe the local rotation from elastic and non-elastic deformation caused by earthquakes to fully observe the seismic wavefield. (2) The next generation of gravitational wave detectors relies on high-precision rotation measurements for enhanced active seismic noise isolation and Newtonian noise mitigation. (3) Geodesists want to measure the Earth’s rotation rate and its variations with Earth-bound instruments. All these applications require gyroscopes with a sensitivity in the range of 1 prad/s/√Hz to 1 nrad/s/√Hz, covering a frequency range from below 0.01 Hz to up to 100 Hz.This contribution presents (1) a compilation of requirements for a sensor suite to comply with the mission needs, (2) an assessment of the state-of-the-art gyroscope technologies (e.g. fiber-optic gyroscopes, ring-laser gyroscopes, cold atom gyroscopes and mechanical gyroscopes), comprising their scaling parameters as well as technological gaps, and (3) a road map to an ultra-high performance sensor suite for 2030+.