Sheard, BenjaminHeinzel, GDanzmann, KarstenShaddock, DanielKlipstein, WilliamFolkner, William2015-12-102015-12-100949-7714http://hdl.handle.net/1885/70071The Gravity Recovery and Climate Experiment (GRACE) has demonstrated that low-low satellite-to-satellite tracking enables monitoring the time variations of the Earth's gravity field on a global scale, in particular those caused by mass-transport within the hydrosphere. Due to the importance of long-term continued monitoring of the variations of the Earth's gravitational field and the limited lifetime of GRACE, a follow-on mission is currently planned to be launched in 2017. In order to minimise risk and the time to launch, the follow-on mission will be basically a rebuild of GRACE with microwave ranging as the primary instrument for measuring changes of the intersatellite distance. Laser interferometry has been proposed as a method to achieve improved ranging precision for future GRACE-like missions and is therefore foreseen to be included as demonstrator experiment in the follow-on mission now under development. This paper presents the top-level architecture of an interferometric laser ranging system designed to demonstrate the technology which can also operate in parallel with the microwave ranging system of the GRACE follow-on mission.Keywords: GRACE; gravimetry; gravity field; interferometry; satellite laser ranging; tracking GRACE; Intersatellite ranging; Laser interferometry201210.1007/s00190-012-0566-32016-02-24