Space Geodesy Project (SGP)

The global geodetic infrastructure is comprised of several networks and individual ground stations for: Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Global Navigation Satellite Systems (GNSS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS). NASA's Space Geodesy Program contributes to the global infrastructure through the deployment, operation, and maintenance of two coordinated networks: the NASA Space Geodesy Network (NSGN) of collocated VLBI, SLR, GNSS, and DORIS stations, and the NASA Global GNSS Network (GGN).