An award-winning mission that's changed the way we study Earth's gravitational forces, the Gravity Recovery and Climate Experiment, or GRACE, mission flies twin spacecraft in tandem around Earth to study key changes in the planet's waters and ice sheets.

In 2011, the gravity measurement technique pioneered by GRACE, which works by measuring changes in the push and pull between the twin spacecraft as they orbit Earth, was put to use on NASA's twin GRAIL spacecraft embarking on an ambitious mission to study the gravitational forces of Earth's moon.

Scientific Instrument(s)

- Microwave K-band ranging instrument
- Accelerometers
- Global Positioning System receivers