NASA’s Gravity and Climate Experiment (GRACE) is an audacious mission to track the impact of climate change on the planet’s vast tracts of freshwater, saltwater, and ice. GRACE’s pair of satellites responds to the gravitational pull of these massive stores, effectively “weighing” Earth’s shifting water resources month by month. The satellites can detect where water is accumulating and drying up on a grand scale—data that were unavailable before. GRACE’s unprecedented view of our water planet could prove critical in the effort to anticipate and manage the consequences of climate change for people worldwide.