remote sensing

remote sensing
Name	Remote sensing
Caption	Earth observation satellite imagery
Field	Earth observation, geospatial science
Established	mid-20th century

remote sensing

Remote sensing is the acquisition of information about the Earth's surface, atmosphere, and oceans from a distance using sensors aboard aircraft, satellites, and other platforms. Practitioners draw on techniques from optical engineering, National Aeronautics and Space Administration, European Space Agency, Japan Aerospace Exploration Agency, Indian Space Research Organisation, and China National Space Administration to produce data used by agencies such as United States Geological Survey, European Commission, Food and Agriculture Organization, World Meteorological Organization, and United Nations Educational, Scientific and Cultural Organization. The field intersects with satellite missions like Landsat program, Copernicus Programme, Sentinel-2, Terra (satellite), and Aqua (satellite).

Overview

Remote sensing integrates instrumentation from projects such as Hubble Space Telescope, Envisat, SPOT (satellite), RADARSAT, and ICESat to monitor phenomena studied by organizations including National Oceanic and Atmospheric Administration, United Nations Environment Programme, European Space Agency Directorate of Earth Observation, NASA Jet Propulsion Laboratory, and USGS EROS Center. Key objectives align with programs like Global Precipitation Measurement and Gravity Recovery and Climate Experiment and inform policy instruments such as the Paris Agreement and initiatives by World Bank and International Monetary Fund where environmental data guide decision-making. Collaboration often involves universities such as Massachusetts Institute of Technology, Stanford University, University of Oxford, Peking University, and Indian Institute of Science.

History and development

Early roots trace to aerial photography in projects by Orville Wright and military uses during the First World War, later expanding through initiatives in the Second World War and Cold War-era reconnaissance programs like Corona (satellite), KH-11 Kennen, and research at Los Alamos National Laboratory. Civilian programs emerged with the Landsat program partnership between NASA and USGS, while international cooperation produced ERS-1, ERS-2, and Envisat under European Space Agency auspices. Technological milestones include the development of multispectral sensors on Landsat 1, the launch of radar systems on SEASAT, and the advent of lidar campaigns associated with projects at National Center for Atmospheric Research.

Principles and methods

Fundamental principles rely on electromagnetic spectrum interactions used by instruments developed at institutions like Jet Propulsion Laboratory, Rutherford Appleton Laboratory, Max Planck Institute for Solar System Research, and Chinese Academy of Sciences. Methods include passive optical imaging exemplified by MODIS and hyperspectral analysis in missions informed by research at California Institute of Technology, as well as active sensing techniques such as synthetic aperture radar pioneered in programs like RADARSAT-2 and lidar systems advanced by NASA Goddard Space Flight Center. Radiative transfer models, calibrated using standards from National Institute of Standards and Technology and validated in field campaigns associated with International Geosphere-Biosphere Programme and Global Climate Observing System, underpin retrieval algorithms.

Platforms and sensors

Platforms span payloads on satellites from agencies such as NOAA, ESA, JAXA, and ISRO as well as manned aircraft sorties operated by Royal Air Force, United States Air Force, and research flights from National Oceanic and Atmospheric Administration Aircraft Operations Center. Sensor types include optical imagers like those on Landsat 8 and Sentinel-2, thermal infrared units used in Terra (satellite) operations, microwave sensors on SMAP (satellite), and altimeters like those on ICESat-2. Emerging platforms feature small satellites from companies such as Planet Labs, constellation efforts by SpaceX and OneWeb, and unmanned aerial vehicles developed at AeroVironment and research centers like Wageningen University & Research.

Applications

Applications permeate efforts by Food and Agriculture Organization for crop monitoring, World Health Organization for disease vector habitat mapping, United Nations Office for Disaster Risk Reduction for hazard assessment, and urban planning used by municipal programs in New York City, London, and Beijing. Environmental monitoring supports work by Greenpeace and WWF in deforestation studies tied to campaigns in Amazon Rainforest and Congo Basin, while hydrology and oceanography draw on data for projects like Argo (oceanography), coastal management in Great Barrier Reef studies, and ice sheet research in Antarctica coordinated with British Antarctic Survey and Scott Polar Research Institute. Archaeological remote sensing has aided discoveries near Angkor Wat and Machu Picchu using techniques developed at University of Cambridge and University of Arizona.

Data processing and analysis

Processing chains implement algorithms from research groups at MIT Lincoln Laboratory, CSIRO, European Centre for Medium-Range Weather Forecasts, and Lawrence Livermore National Laboratory to execute radiometric correction, geometric registration, atmospheric correction, and classification using software such as tools from Esri, Google Earth Engine, ENVI, and open-source projects from OpenGeospatial Consortium partners. Machine learning models inspired by work at Google DeepMind, Facebook AI Research, and Microsoft Research enable object detection, land-cover mapping, and time-series analysis with workflows integrated into platforms supported by Amazon Web Services, Microsoft Azure, and national data centers like Copernicus Data Space Ecosystem.

Limitations and challenges

Challenges persist in calibration traceability linked to standards from International Organization for Standardization, data gaps from cloud cover affecting optical missions like Landsat and Sentinel-2, and geopolitical constraints exemplified by export controls related to technologies studied by Department of Commerce (United States) and treaties such as the Outer Space Treaty. Issues of data access and equity surface in debates involving World Bank funding, proprietary commercial constellations from firms like Maxar Technologies, and capacity-building initiatives led by United Nations Office for Outer Space Affairs and regional centers including African Union programs. Technical limitations include signal-to-noise ratios in microwave sensors, processing bottlenecks addressed by high-performance computing centers at Oak Ridge National Laboratory and ethical concerns raised in forums hosted by Institute of Electrical and Electronics Engineers and Association for Computing Machinery.

Category:Earth observation