The Gravity Recovery and Climate Experiment Follow-on (GRACE-FO) mission is a partnership between NASA and the German Research Centre for Geosciences (GFZ). GRACE-FO is a successor to the original GRACE mission, which operated from April 2002 through July 2017. Since June 2018, GRACE-FO carries on the extremely successful work of its predecessor while testing a new technology designed to dramatically improve the already remarkable precision of its measurement system.
The GRACE missions measure small month-to-month variations in gravity over Earth's surface arising from the constant redistribution of mass. Changes in how mass is distributed within and between Earth’s atmosphere, oceans, groundwater and ice sheets are fundamental indicators of the large-scale dynamics of the planet. Monitoring changes in ice sheets and glaciers, near-surface and underground water storage, the amount of water in large lakes and rivers, as well as changes in sea level and ocean currents provides an integrated global view of how Earth’s water cycle and energy balance are evolving — measurements that have far-reaching impact on our understanding of the Earth system and important applications for everyday life. In addition to tracking mass change, each of the two satellites uses GPS antennas to supply at least 200 profiles of atmospheric temperature distribution and water vapor content daily to aid in the monitoring and forecasting of weather.