On March 17, 2002, NASA and the German Aerospace Center (DLR) launched the Gravity Recovery and Climate Experiment (GRACE), a novel space mission that has given scientists a new understanding of changes in Earth's natural systems. The identical twin GRACE spacecraft track changes in Earth's gravity field caused by local changes in Earth's mass due to the seasons, weather patterns, short-term climate change and even large earthquakes. Grace has given us monthly measurements of Earth’s mean gravity field that are at least 100 times more precise than predecessors, substantially improving the accuracy of techniques used by oceanographers, hydrologists, glaciologists, geologists and climate scientists. The result has been an amazing array of breakthrough science. Here are some highlights.