GRATTIS Mission (IMAGE) University of Florida Caption The GRATTIS spacecraft in Earth orbit with two Gravitational Reference Sensors on board. The spacecraft serves as a test platform for next-generation inertial reference systems to track mass movement across Earth’s surface, providing insight into climate science, geology, oceanography, and hydrology. Credit Simon Barke/UF Usage Restrictions n/a License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.