NASA's Gravity Recovery and Climate Experiment (GRACE) mission which last for 15 year has come to an end.
- The mission was carried out in cooperation with the German space agency DLR
- The decision to end the mission was taken after the retirement of one of its twin spacecraft Grace 2.
- The spacecraft was facing problems because of the failure of several battery cells, which caused a loss of contact with the spacecraft in early September.
- GRACE-2 is expected to reenter in December or January.
- GRACE-1's batteries are healthy and it will operate for the remainder of the year to collect calibration data. It will reenter in early 2018.
- Two GRACE spacecraft was launched by NASA and DLR in March 2002.
- The mission was expected to be a five-year mission.
- Scientists use measurements of very small changes in the separation of the two satellites in low Earth orbit to calculate local changes in gravitational field caused by mass variations in the Earth.
- Those measurements can, in turn, be used to track motions of water around the Earth caused by seasonal patterns and climate processes.
- NASA and the Helmholtz Centre Potsdam German Research Centre for Geosciences has developed a successor mission, called GRACE Follow-On.
- The two spacecraft will launch in early 2018 on a SpaceX Falcon 9 on a mission shared with five Iridium Next satellites.
