The laser ranging interferometer (LRI) aboard the Gravity Recovery and Climate Experiment Follow-on (GRACE-FO) platform uses a laser to measure the distance between the twin satellites. By analyzing minute changes in the relative distance between the two satellites, researchers can derive information to estimate Earth's gravity field. 

The GRACE-FO satellites are in part designed to test and demonstrate the LRI, which has the potential to improve the precision of separation distance measurements on future GRACE satellites by a factor up to 20. GRACE-FO LRI data are for technology demonstration purposes only and will not be the platform's data of record for use by the science community.