Flight Dynamics Challenges for the GRACE Follow-On Mission

The GRACE Follow-On (GRACE-FO) mission is a partnership between NASA and the German Research Centre for Geosciences (GFZ) and will be operated by the German Space Operations Centre (GSOC) / DLR. The baseline launch date is in August, 2017. It is a follow on mission for the successful GRACE (Gravity Recovery and Climate Experiment) mission. Two twin satellites are flying approximately 220 kilometers apart in a polar, nearly circular orbit starting at an altitude of 500 kilometers, which slowly decreases during the mission. For a nominal mission lifetime of 5 years detailed measurements of Earth’s gravity field and atmosphere are collected and provided to the science community to support an understanding of the distribution and flow of mass on and within the Earth. Key tasks are getting into and maintaining the formation of the two satellites and operation of the experimental Laser Ranging Interferometer (LRI) payload allowing highly accurate inter-satellite range rate determination. This paper gives an overview of the GRACE-FO mission and its main Flight Dynamics challenges. A deeper look into the formation acquisition strategy and the operations support of the LRI instrument is provide