23 articles
Copernicus Land Motion service
The Copernicus Land Motion service, known as the European Ground Motion Service (EGMS), uses Sentinel-1 radar data to detect and measure ground movement across Europe with millimeter precision.
Differential interferometric SAR
Differential interferometric SAR (DInSAR) is a radar remote-sensing technique comparing SAR images from repeated satellite passes to measure ground deformation from earthquakes, volcanoes, and subsidence with millimeter precision.
Differential interferometry
Differential interferometry (DInSAR) is a satellite radar remote-sensing method that compares SAR images acquired at different times to measure millimeter-scale ground deformation from earthquakes, volcanoes, landslides, and subsidence.
Etalon (satellite)
Etalon is a pair of Russian passive geodetic satellites, Etalon-1 and Etalon-2, launched in 1989 with GLONASS satellites and covered in corner-cube retroreflectors for satellite laser ranging.
InSAR
InSAR, or Interferometric Synthetic Aperture Radar, is a radar remote-sensing technique combining SAR images of the same area to measure millimeter-to-centimeter ground surface deformation and derive topography.
InSAR time series analysis
InSAR time series analysis is a geodetic method that measures millimeter-scale ground displacement over time from stacks of radar images, monitoring volcanoes, subsidence, and tectonic deformation.
Integer ambiguity resolution
Integer ambiguity resolution (IAR) is the estimation of unknown carrier-phase cycle-count ambiguities as integers, enabling precise GNSS positioning; methods include rounding, bootstrapping, and the LAMBDA method introduced in 1993.
Interferometric synthetic-aperture radar
Interferometric synthetic-aperture radar (InSAR) is a remote-sensing method comparing radar images from repeated satellite passes to map millimeter-scale ground deformation from earthquakes, volcanoes, and subsidence.
International GNSS Service
The International GNSS Service (IGS) is a voluntary federation that collects satellite navigation data from a global network of over 400 ground stations and publishes high-precision products such as orbits and clocks.
Laser altimetry
Laser altimetry is a remote sensing method that measures surface elevation from the flight time of laser pulses, used in studies of ice, land, vegetation, and water.
Laser ranging
Laser ranging measures distances by firing short laser pulses at retroreflector-equipped satellites, the Moon, or spacecraft and timing the reflected light, underpinning Earth's reference frame and tests of general relativity.
Lunar laser ranging
Lunar laser ranging (LLR) is a geodetic technique that times laser pulses fired at retroreflector arrays on the Moon, measuring the Earth-Moon distance to millimeter precision since 1969.
Next Generation Gravity Mission
The Next Generation Gravity Mission (NGGM) is a European Space Agency mission, launching around 2032, that will measure changes in Earth's gravity field to track water and ice movement.
Offset tracking
Offset tracking, also called pixel-offset tracking, is a synthetic aperture radar technique that measures surface displacement, used for glacier flow and large earthquake deformation where InSAR fails.
Persistent scatterer interferometry
Persistent scatterer interferometry, developed at the Politecnico di Milano and first reported in 2000, is a radar technique measuring millimeter-scale ground deformation from stacks of satellite SAR images.
Precise point positioning
Precise point positioning (PPP) is a GNSS technique that estimates centimeter-level positions at a single receiver using precise satellite orbit and clock corrections, without nearby reference stations.
Radar interferometry
Radar interferometry (InSAR) is a remote sensing technique that combines radar signals from two antennas, or one antenna on repeated passes, to measure terrain elevation and surface deformation.
Satellite clock estimation
Satellite clock estimation determines GNSS satellite clock offsets and drifts from code and carrier-phase observations at ground stations, underpinning precise point positioning and real-time navigation.
Satellite laser ranging
Satellite laser ranging (SLR) is a geodetic technique that measures round-trip laser pulse times to satellites carrying retroreflectors, deriving orbits, station positions, and Earth's gravity field.
SECOR (satellite)
SECOR (Sequential Collation of Range), also designated EGRS, was a United States Army geodetic satellite program of 1964 to 1969 that fixed remote positions by electronic trilateration.
Small Baseline Subset
Small Baseline Subset (SBAS) is a differential InSAR time-series method, reported in 2002, that measures ground deformation from stacks of short-baseline SAR interferograms, producing velocity maps and displacement time series.
TerraSAR-X
TerraSAR-X is a German Earth-observation satellite carrying an X-band synthetic aperture radar, launched in 2007 to image Earth in all weather; it later flew with its twin TanDEM-X.
UNAVCO
UNAVCO was a Boulder, Colorado non-profit consortium, founded in 1984 to share GPS equipment and archive geodetic data for Earth science research, merging with IRIS in 2023.