• Gravity measurement missions (for example, CHAMP and GRACE)

  • Atmospheric and ionospheric sounding (GPSMet, Champ, SAC-C, and COSMIC)

In addition to the infrastructure, NASA historically has supported fundamental research and development programs in space geodesy and continues to do so (with increased emphasis on real-time dynamic applications and high spatial and temporal resolution of climatic and tectonic forcings). It is, therefore, not surprising that there is a NASA influence in the treatment of many global scientific problems, including sea-level change, ice budget, ocean circulation, climate change, and geohazards.

National Geospatial-Intelligence Agency (NGA)

The mission of the NGA Office of GEOINT Sciences is to provide accurate and timely geodetic, geophysical, and geospatial analysis and intelligence information to support the DoD’s national security and intelligence objectives. The NGA supports satellite geodesy by maintaining its permanent GPS tracking network and implementing improvements to GPS orbit determination. The NGA also works to maintain and improve the World Geodetic System 1984 (WGS 84), the reference frame currently used by GPS and the Department of Defense. Further, NGA is responsible for collecting, processing, and evaluating geodetic data, which are used to compute the WGS 84 Earth Gravitational Model, geomagnetic models, and global digital terrain models.

National Oceanic and Atmospheric Administration (NOAA)

NOAA, through the National Geodetic Survey (NGS), has the federal mandate for defining, maintaining, and providing access to the National Spatial Reference System (NSRS). The NSRS allows consistent positioning to meet a wide range of needs, from delineating property lines and exclusive economic zones to determining the heights of levees and tide gauges relative to sea level. Historically, NGS installed thousands of survey monuments across the nation in support of the NSRS. By establishing a network of Continuously Operating Reference Stations (CORS) using GPS and by making the observational data available, NGS now allows users to connect directly to the NSRS without the need to place receivers at NGS survey monuments. Each CORS site provides GPS carrier phase and code range measurements to support three-dimensional positioning activities throughout the United States and its territories, with accuracies that approach a few centimeters, measured in the NSRS, both horizontally and vertically. The CORS system is operated in partnership with many local, state, and federal agencies, and contains CORS stations that are located at sites of varying positional stability and with various models of receivers, antennas, and documentation.

In cooperation with the USGS, NOAA also has responsibilities for supporting the geodetic infrastructure to provide ocean bathymetry, coastline and sea surface topography, which are critical for understanding tsunamis and predicting where they might come ashore, as well as for determining local or regional changes in sea level. NOAA further cooperates with NASA and USNO in the National Earth Orientation Service, or NEOS. NOAA’s National Geodetic Survey chairs the Federal Geodetic Control Subcommittee (FGCS) of the Federal Geographic Data Committee (FGDC), with membership drawn from all federal agencies involved in surveying, mapping and geospatial data, to promote a common standard of content, format and accuracy for geodetic data for the nation.

National Science Foundation (NSF)

The NSF supports a large number of scientific research projects that depend on the geodetic infrastructure. In addition, the NSF supports national geodetic infrastructure through financial support for the UNAVCO Facility (formerly known as the University NAVSTAR Consortium) and the



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