EarthScope program, which facilitate testing, adoption, and implementation of geodetic technologies to support fundamental geodynamic research, such as the study of earthquakes and volcanic eruptions. The Plate Boundary Observatory (PBO)—a component of EarthScope—provides geodetic imaging of plate boundary deformation.
The National Executive Committee for Space-Based Positioning, Navigation, and Timing (PNT) coordinates policy activities relating to the Global Positioning System (GPS) and Global Navigation Satellite Systems (GNSS). It is chaired jointly by the Deputy Secretaries of Defense and Transportation. The Space-Based PNT National Coordination Office staffs the operational activities of the National Executive Committee. A formal Federal Advisory Board provides external advice and recommendations on PNT issues to the National Executive Committee.
Although data from some GPS stations operated by USGS are processed by the International GNSS Service, they are not used to to maintain the International Terrestrial Reference Frame. USGS depends on geodetic infrastructure to cary out its earthquake and volcano monitoring mission, and that infrastructure is crucial to development and production of data products, such as hazard maps and real-time ShakeMaps.
The USNO is responsible for establishing, maintaining, and coordinating the astronomical reference frames for celestial navigation and orientation of space systems. Specifically, the USNO is the sole provider of the Earth Orientation Parameters (EOP) to the Department of Defense. USNO also serves as the official source of time for the Department of Defense and a standard of time for the entire United States.
Many international services have been established in response to the need for international cooperation to support geodetic activities. The most important of these services are the International Earth Rotation and Reference System Service (IERS) (Vondrák and Richter, 2004); the International GNSS Service (formerly the International GPS Service, or IGS) (Dow et al., 2005); the International VLBI Service (IVS) (Schlüter et al., 2002); the International Laser Ranging Service (ILRS) (Pearlman et al., 2002); and the International DORIS Service (IDS) (Tavernier et al., 2006). These services are described in more detail in Chapter 4. In general, the Central Bureau for each service is supported by the host country with volunteer contributions by the international scientific community. For example, the Central Bureaus for the IGS, IVS, and ILRS are all hosted in the United States and are supported by NASA.