Explanation:

• 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 began orbiting Earth on March 17, 2002. The GRACE missions measure variations in gravity over Earth’s surface, producing a new map of the gravity field every 30 days.
• GRACE-FO will continue the work of tracking Earth’s water movement to monitor changes in underground water storage, the amount of water in large lakes and rivers, soil moisture, ice sheets and glaciers, and sea level caused by the addition of water to the ocean.