MGO employs three main techniques used in space geodesy research:
- Space Geodesy Satellite Laser Ranging (SGSLR)
- Global Navigation Satellite System (GNSS), including the U.S. Global Positioning System (GPS), the Russian Global Navigation Satellite System (GLONASS), the European Galileo System, Chinese Beidou system (BDS), and the Japanese Quasi-Zenith Satellite System (QZSS)
- Geodetic Very Long Baseline Interferometry (Geodetic VLBI)
To meet requirements for characterizing the Terrestrial Reference Frame (TRF) at 1 mm accuracy and 0.1 mm/year stability, these colocated systems are “tied” together through (a) a precise initial site survey and (b) several ongoing local motion monitoring techniques.
Why multi-technique core sites?
- VLBI orients the TRF to the celestial sources (quasars) and constrains the scale of the TRF.
- SLR provides absolute scale and connects the TRF to the center of mass of the Earth System.
- GNSS provides spatio-temporal densification and dissemination of the TRF.
Gravity measurements are added to integrate geometry and dynamics – Geoid-based height systems are the basis for US National Spatial Reference System
Research is being carried out by the University of Texas at Austin to help reduce the km-scale network of instruments to mm-precision (virtual) fiducial point.
- Signal propagation and environmental effects – measurement and modeling
- Inter-technique ties, needed for synthesis
- Instrument system characterization (bias, drift, etc)