US, Germany Partnering on Mission to Track Earth’s Water Movement
Researchers can gauge those changes by measuring very small changes in the distance between the two GRACE-C satellites. As the lead spacecraft flies over an area with relatively more mass – like a spot with more groundwater than its surroundings – the slight increase in Earth’s gravity field pulls the satellite forward, increasing its distance from the trailing spacecraft. Capable of measuring distance changes 100 times smaller than the thickness of a human hair, a laser ranging interferometer (LRI) instrument continually measures the distance between the two spacecraft.
The satellite systems and orbit for GRACE-C will be similar to those of GRACE-FO, ensuring the continuity of measurements between the two missions.
“GRACE-C will build on decades of observations of the global movement of water and changes in water resources. This is critical to informing predictions of future trends in our climate and to assess food and water security,” said Frank Webb, GRACE-C project scientist at NASA’s Jet Propulsion Laboratory in Southern California. “The mission is an example of the commitment that NASA and our German partners share for studying the Earth and helping society better prepare for a warming world.”
GRACE-C, previously known as the Mass Change mission, addresses one of the key goals outlined in the 2017 Decadal Survey for Earth Science conducted by the U.S. National Academies of Science, Engineering, and Medicine: to better understand the planet’s global water cycle through large-scale changes in Earth’s mass.
“Together with NASA, we are now continuing along the GRACE route in Earth observation, thereby strengthening our international cooperation in space-based research,” said Walther Pelzer, a member of the DLR executive board and director general of the German Space Agency at DLR. “The USA and Germany have been working closely together for a long time on climate and environmental research from space. The trust that our U.S. partners are placing in German space expertise for these missions by commissioning the satellite construction and the delivery of important parts of the GRACE-C instrumentation and mission control is also a sign of Germany’s capabilities as a prime location for spaceflight.”
The mission will be part of NASA’s Earth System Observatory (ESO), a set of Earth-focused missions that will provide data to guide efforts related to climate change, natural hazard mitigation, wildfire management, and food security. When combined, ESO mission data will create a holistic view of Earth from the planet’s atmosphere to its bedrock.
More About the Mission
JPL manages the GRACE-C mission for NASA and will procure the two spacecraft from Airbus Defence and Space, the company that built the satellites for the GRACE and GRACE-FO missions. Development and construction of the LRI system will be led by JPL, which is managed for NASA by Caltech in Pasadena. The German contributions are funded by the German Federal Ministry of Economic Affairs and Climate Action and the Federal Ministry of Education and Research. The German Space Agency at DLR will manage the German contributions to GRACE-C, providing the LRI optics subsystems; mission operations; telemetry, tracking, and command; the ground data system; the laser retroreflectors to help with satellite positioning; the launch vehicle; and launch services.
To learn more about GRACE-FO, visit:
