GRACE was a joint partnership between the National Aeronautics and Space Administration (NASA) in the United States and Deutsche Forschungsanstalt für Luft und Raumfahrt (DLR) in Germany. Project management and systems engineering activities were carried out by the Jet Propulsion Laboratory.

It was the first Earth-monitoring mission in history whose key measurement was not derived from electromagnetic waves either reflected off, emitted by, or transmitted through Earth's surface and/or atmosphere. Instead, the mission used a microwave ranging system.

GRACE's successor - GRACE Follow-On (GRACE-FO) - was launched in 2018.

GRACE consisted of two identical spacecraft that flew approximately 220 kilometres apart in a polar orbit 500 kilometres above Earth. GRACE mapped Earth's gravity field by making accurate measurements of the distance between the two satellites, using GPS and a microwave ranging system. It has provided scientists with an efficient and cost-effective way to map Earth's gravity field with unprecedented accuracy.

The results from this mission are yielding crucial information about the distribution and flow of mass within Earth and its surroundings.

The gravity variations studied by GRACE include:

• Changes due to surface and deep currents in the ocean
• Run-off and ground water storage on land masses
• Exchanges between ice sheets or glaciers and the ocean
• Variations of mass within Earth

Another goal of the mission is to create a better profile of Earth's atmosphere.

GRACE results are making a huge contribution to the goals of NASA's Science Mission Directorate, Earth Observation System (EOS) and global climate change studies.

GRACE-1 and GRACE-2 flew approximately 220 kilometres apart in a polar orbit 500 kilometres above Earth. They operated in a circular polar co-planar orbit -the initial altitude was 485 km at launch (near a solar maximum), decaying to about 300 km (near a solar minimum) after five years.

DLR-GSOC (German Space Operations Centre) in Oberpfaffenhofen, Germany was responsible the operation of the two GRACE satellites with its ground stations in Weilheim and Neustrelitz, also in Germany.

• GRACE Website*
• GRACE on the eoPortal*
  

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