GRACE-FO geosciences satellite in Earth orbit, illustration. The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) satellite is a partnership between NASA and the German Research Centre for Geosciences (GFZ). It consists of two twin spacecraft, enabling it to measure variations in gravity over the Earth's surface. GRACE-FO will track the evolution of Earth's water cycle by monitoring changes in the distribution of mass on Earth. It was launched on 22 May 2018.