Towards realization of a GRACE Gap Filler Mission

During 8 years of very successful operation in orbit, the US-German GRACE mission has demonstrated in a very impressive way its outstanding capability to monitor mass motions in the Earth system with unprecedented accuracy and temporal resolution. These results have stimulated many novel research activities in hydrology, oceanography, glaciology, geophysics and geodesy, which also indicate that long term monitoring of such mass motions, possibly with improved spatial and temporal resolution is a must for further understanding of various phenomena.