Status of the GRACE Follow-On Mission

The Gravity Recovery and Climate Mission (GRACE) has been so far the only satellite mission capable of monitoring mass variations in the Earth system and has made many breakthroughs in the understanding of Earth system dynamics. The mission has been operating for over 10 years at the time of this paper. Expected end of mission is dependent on future solar activity, instrument conditions and-most likely-on the battery health. Due to the extreme success of GRACE in many Earth science disciplines there was a long-standing strong request by the user community to launch a GRACE Follow-On (GRACE-FO) mission as soon as possible to extend the GRACE mass transport time series with the minimum practical data gap between both missions. GRACE-FO has in fact been approved by the NASA and German ministries BMBF (Federal Ministry of Education and Research) and BMWi (Federal Ministry of Economics and Technology), and will be implemented under US-German partnership. GRACE-FO entered Phase-A in January 2012 and Phase-B in September 2012. The current target launch date is August 2017. This paper summarizes the status of the various mission elements.