JPL News: Twin Spacecraft Launch to Track Earth's Water Movement

A joint U.S./German space mission to track the continuous movement of water and other changes in Earth's mass on and beneath the planet's surface successfully launched at 12:47 p.m. PDT (3:47 p.m. EDT) Tuesday from the California coast.

The twin spacecraft of the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO), a joint NASA/German Research Centre for Geosciences (GFZ) mission, lifted off on a SpaceX Falcon 9 rocket from Space Launch Complex 4E at Vandenberg Air Force Base in California, sharing their ride into space with five Iridium NEXT communications satellites.

Ground stations have acquired signals from both GRACE-FO spacecraft. Initial telemetry shows the satellites are performing as expected. The GRACE-FO satellites are at an altitude of about 305 miles (490 kilometers), traveling about 16,800 mph (7.5 kilometers per second). They are in a near-polar orbit, circling Earth once every 90 minutes.

"GRACE-FO will provide unique insights into how our complex planet operates," said Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate at NASA Headquarters in Washington. "Just as important, because the mission monitors many key aspects of the Earth's water cycle, GRACE-FO data will be used throughout the world to improve people's lives -- from better predictions of drought impacts to higher-quality information on use and management of water from underground aquifers."

Over its five-year mission, GRACE-FO will monitor the movement of mass around our planet by measuring where and how the moving mass changes Earth's gravitational pull. The gravity changes cause the distance between the two satellites to vary slightly. Although the two satellites orbit 137 miles (220 kilometers) apart, advanced instruments continuously measure their separation to within the width of a human red blood cell.

Read the full story from JPL News.