Precise Geodetic Infrastructure: National Requirements for a Shared Resource (2010)Board on Earth Sciences and Resources
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Geodesy is the science of accurately measuring Earth's shape, orientation in space, and gravity field, and changes in these parameters over time. Geodetic techniques and instrumentation have enabled scientists to determine the changing position of any point on Earth with centimeter accuracy or better. They also provide the underpinnings for surveying and navigation, determining flood maps, measuring sea level rise, assessing groundwater resources, and monitoring earthquakes and other natural hazards. Geodetic measurements are made using a variety of satellites, ground-based sensors and receivers, laser ranging devices, radio beacons, radio telescopes, and data-integration methods—a set of tools collectively known as the precise geodetic infrastructure.
U.S. federal agencies, in collaboration with international partners, led the development of much of the geodetic infrastructure that exists today. At their request, the National Research Council has assessed geodesy's benefits and future infrastructure needs. The report finds that some of the critical ground station networks of the space-based geodetic observing systems have become increasingly fragile and recommends that the United States invest in upgrading and maintaining them. As multiple agencies and organizations contribute to the global geodetic infrastructure, the report also recommends that a federal geodetic service be organized to coordinate and facilitate the modernization and long-term operation of the U.S. components.
- Despite the reliance of many stakeholders on high-precision geodetic infrastructure, there is no formal governance structure or lead agency explicitly responsible for this infrastructure. Its many components have been developed separately, often to serve specific needs.
- Geodetic observing systems provide a significant benefit to society in an wide array of military, research, civil, and commercial areas, including sea level change monitoring, autonomous navigation, tighter low flying routes for strategic aircraft, precision agriculture, civil surveying, earthquake monitoring, forest structural mapping and biomass estimation, and improved floodplain mapping
- Many new applications would benefit from a real-time GNSS/GPS data stream. These applications include: autonomous navigation for land, sea, and air vehicles and robotic equipment; precision tracking of aircraft for laser and radar imaging; monitoring of space weather with potential to affect power grids, navigation, and communications; forecasting for extreme weather events; measurement of ground displacement in landslides; early warning systems for earthquakes and tsunamis; and monitoring of such critical structures as bridges, dams, railways, and pipelines.
- One of the "weakest links" in the maintenance of a precision geodetic infrastructure is a lack of a trained workforce to develop and maintain the infrastructure in the coming decades. As a science, geodesy has long been a niche discipline, populated by a small group of experts. Agencies are finding it difficult to replace these highly skilled geodesists as they retire, and instead are forced to hire young professionals from other disciplines whom they must train on the job.
- Scientists use geodetic techniques to monitor the precise locations of a set of reference points around the world and their change over time. Together, these points form a reference frame that can be used to determine the position of other points on the Earth. These results are critical to maintaining the accuracy of GPS and other navigation systems.
- Since the advent of the space age, we have seen remarkable improvements in positioning, navigation, and timing of approximately one order of magnitude each decade with no indication that this rate of progress is abating. This is the object of precise global geodesy. But the underlying infrastructure is at risk and its fragility a matter of serious concern.
- The nation's precise geodetic infrastructure has not been considered holistically before now. Nevertheless, the geodetic infrastructure is a shared asset that is required for the nation to maintain its global leadership in economic and scientific spheres and to sustain national security into the future. Cooperation between and within national agencies and international services is essential to ensure the long-term viability of the geodetic infrastructure.
- The past decades have seen tremendous growth in the utilization of observations and methods that are dependent on the geodetic infrastructure for scientific and practical applications, and today many billions of dollars are invested in U.S. satellites and ground-based networks that rely on the high-precision geodetic infrastructure. The geodetic infrastructure, however, is currently operating far below its optimal state, both in terms of number of sites and in modernization of instrumentation.
- There seems to be no end to the list of scientific problems, technical endeavors, and societal activities that depend directly or indirectly on the global precise geodetic infrastructure.
- Using geodetic techniques, scientists can measure subtle changes in the surface of the Earth that are associated with earthquakes, tsunamis, landslides, and volcanic eruptions. For example, geodetic instruments can detect a slight uplift in the ground occurring around a volcano before it erupts. Although they are now in early stages of development, high-precision real-time geodetic observation systems placed in areas of risk could help provide early warning for these hazards.
- With high-accuracy positioning information from the geodetic infrastructure, farmers can plant crops in innovative patterns—such as interlacing two compatible crops on the same field—for higher efficiency and environmental benefit. Geodesy has also improved soil moisture monitoring and the accuracy of weather predictions.