geo-Q will focus on three new measurement techniques that primarily address three goals:
- To track the motion of test masses in the gravitational field with nanometer accuracy and beyond, we will study spaceborne laser interferometric distance and acceleration measurements. We will design instruments for ranging between satellites as well as interferometers linking multiple test mass constellations within one satellite. This research will extend the frontiers of optics and optical measurements in space, and create the foundation for satellite missions to monitor global gravity and mass variations with the accuracy and spatial resolution that will allow resolving important questions, e.g., on the causes of ice mass loss and on deep ocean circulation.
- We will develop atomic gravity sensors, based on the principles of atomic interferometry, that are capable of (quasi) continuous absolute gravity measurements on ground with μGal accuracy and better. We will advance the physics of sensors in the ultra-cold temperature regime and investigate their potential for monitoring geophysical processes involving regional mass variations in the water cycle and in the solid Earth with appropriate sampling in space and time. The main strategy will be to achieve compact, transportable devices designed for geodetic field use without sacrificing accuracy. Complementarily, we will explore large, stationary atom fountains to explore gravity sensing in a completely new range of accuracy.
- We will establish the quantum metrology of long-distance frequency comparisons to observe the gravitational frequency redshift with optical atomic clocks connected by phase-stabilized optical fiber links at the 10−17 accuracy level and beyond. At a later stage, we will study the extension of the concept to include optical satellite links. We will use the observations to apply – for the first time – the principles of relativistic geodesy to directly determine differences of the geopotential, the geoid and heights in points of geodetic networks. The far reaching perspective in this field is to tie observations of the gravitational field to atomic frequency standards and to create the missing ground network for a strong and homogeneous terrestrial dynamic reference frame for geodesy.
Please refer to the geoQ Projects for more details.