Signing the agreement: Lori Garver und Jan Wörner
Launched in March 2002, GRACE tracks changes in Earth's gravity field by noting minute variations in gravitational pull from local changes in Earth's mass. To do this, GRACE measures, to one-hundredth the width of a human hair, changes in the separation of two identical spacecraft in the same orbit approximately 137 miles (220 kilometers) apart. The agreement is an amendment to the Memorandum of Understanding that was signed by NASA and DLR in 1998.
"The signing extension demonstrates the strength of the NASA-DLR partnership and our commitment to continue working together in this very important area of Earth science," said Deputy Administrator Garver.
NASA and DLR jointly developed the GRACE mission and have cooperated on its operational phase since its launch in March 2002. For the twin satellite mission, NASA provided the instruments and selected satellite components plus data validation and archiving. DLR provided the primary satellite components, launch services and operations.
GRACE maps gravity-field variations from month to month, following changes imposed by the seasons, weather patterns and short-term climate change.
Lori Garver and Thomas Reiter
"The extension of the very successful mission will deliver more valuable data that will help us understand how Earth's mass and gravity varies over time. This is an important component necessary to study changes in global sea level, polar ice mass, deep ocean currents, and depletion and recharge of continental aquifers. We appreciate the strong cooperation with our partner NASA", said DLR Chairman Woerner.
GRACE's monthly maps are up to 100 times more accurate than existing maps, substantially improving the accuracy of techniques used by oceanographers, hydrologists, glaciologists, geologists and climate scientists.
Data from the GRACE mission has been used to measure the amount of water lost in recent years from the aquifers for California's primary agricultural region, the Central Valley. An international study recently used GRACE data to show that ice losses from Greenland's ice sheet are now spreading rapidly up its northwest coast.