Future satellite gravity field missions – Impact of quantum sensors and extended satellite constellations

With the evolution of cold atom interferometry (CAI), an adaptation for spaceborne applications may become possible in the near future. One of the applications which may benefit from such CAI instruments are next-generation satellite gravity field missions (NGGMs), since they rely heavily on the accelerometer performance. Here, either future satellite-to-satellite tracking (SST) missions (such as GRACE/-FO) or satellite gravity gradiometry (SGG) missions (such as GOCE) are feasible. Until now, only electrostatic accelerometers have been used. However, all suffer from an increased long-term instability which affects the accuracy of the long wavelengths of the retrieved gravity field. In this contribution we investigate the impact of CAI sensors on various NGGM mission concepts (either SST or SGG variants) and quantify the instrument-only error separately from the full gravity field retrieval error (which is hampered by temporal aliasing). Knowing that temporal aliasing currently poses one of the main limiting factors, special attention is given to strategies which may help to minimize this error source. Therefore, in addition to investigating future instruments, also extended mission constellations containing several satellites/pairs and alternative satellite configurations are examined with respect to their time-variable gravity field retrieval performance. This work is supported by the ESA QSG4EMT study in collaboration with Politecnico di Milano, Delft University of Technology, HafenCity University Hamburg, University of Bonn and University of Trieste.