Airborne Absolute Gravimetry Using Cold-Atom Interferometry : First Experiment And Comparisons With Classical Technologies

We present here the results of a first airborne absolute gravity survey carried out using an innovative instrumentation (GIRAFE-2) based on matter-wave interferometry and discuss the benefits of cold-atom gravimetry on moving platforms for Earth's sciences.

The GIRAFE-2 instrument is originally a marine gravimeter based on atom technology designed and built by ONERA and successfully tested at sea by SHOM and ONERA. First results and comparisons with spring gravity meters have demonstrated the remarkable performances of this new instrumentation. According to the high potential of these technologies for airborne gravity surveys (extensively used for regional gravity or geoid determinations), a dedicated survey was designed in order to evaluate the performance of GIRAFE-2 instrument for such data acquisition.

An airborne survey was thus carried out in France during Spring 2019 and performed on board of an ATR42 aircraft from SAFIRE (a joint facility of CNRS, Météo-France and CNES dedicated to flying research aircraft). In addition, other instrumentations commonly used for airborne surveys (LaCoste & Romberg, Strapdown IMU) were also implemented for side-by-side comparisons. Different flights aimed at mapping land-sea transitions and mountainous areas and the measuring of a well-controlled reference profile were done. The performances of the GIRAFE-2 instrument are discussed with respect to the other instruments and to the available ground data in surveyed areas. We confirm that the obtained sensitivity and accuracy perfectly fits with the requirements of precise airborne surveys.

Such promising instrumentation opens unprecedented perspectives for acquiring absolute gravity measurements on moving platforms and providing homogeneous and accurate observations from continental to marine areas. This is of special interest for future mapping of the Earth's gravity field in areas poorly determined by satellite or any other conventional observations (i.e. coastal or low depths marine areas; mountainous areas; volcanoes) and for providing an absolute and common reference to other gravity observations. Cold-atom absolute gravimetry is believed to play a major role for bridging the gap between satellite and terrestrial measurements and improving accurate regional or global mapping of the Earth's gravity.