Shuttle Radar Topography Mission

Shuttle Radar Topography Mission was a joint project led by National Aeronautics and Space Administration and supported by National Geospatial-Intelligence Agency, National Imagery and Mapping Agency, German Aerospace Center (DLR), and other institutions. The mission used a radar interferometer aboard Space Shuttle Endeavour on STS-99 to map nearly global topography, producing digital elevation models that transformed cartography, geology, hydrology, and remote sensing applications. Its week-long flight generated datasets widely used by United States Geological Survey, European Space Agency, United Nations, and academic centers.

Mission overview

The mission launched from Kennedy Space Center on February 11, 2000, as part of STS-99 operations with crew including Kevin R. Kregel, Gerald R. Carr, Janet L. Kavandi, and Janice E. Voss. The payload included a 60-meter mast manufactured by DLR and a radar instrument developed by Jet Propulsion Laboratory and NGA. Orbiting in Low Earth orbit, the mission acquired interferometric synthetic aperture radar (InSAR) data over most of Earth's land between 60° north and 56° south, complementing datasets from Landsat and Terra. Coordination involved agencies such as USGS and research groups at MIT, Caltech, and Ohio State University.

Instrumentation and technology

The core hardware combined a dual-frequency X-band and C-band radar system engineered by NASA Jet Propulsion Laboratory and DLR teams, plus the 60-meter deployable mast and a precision control system built by contractors including Boeing and Ball Aerospace. The radar used interferometric techniques pioneered in missions like Shuttle Imaging Radar and technologies related to SIR-C/X-SAR. The mast replicated concepts from structural dynamics research at Massachusetts Institute of Technology and materials tested at Ames Research Center; attitude and orbital control referenced systems developed for Hubble Space Telescope servicing missions. Ground stations at White Sands Complex and international partners such as German Space Operations Center received telemetry. Instrument calibration drew on standards from National Institute of Standards and Technology and flight heritage from Magellan and RADARSAT.

Data processing and products

Raw interferometric phase data were processed into digital elevation models (DEMs) and orthorectified radar backscatter mosaics by pipelines at Jet Propulsion Laboratory, NASA Ames Research Center, and processing centers at DLR and USGS. Products included 1 arc-second (~30 meter) and 3 arc-second (~90 meter) DEMs, later reprocessed to provide void-filled and hydro-flattened derivatives used by OpenStreetMap contributors, Google Earth, and scientific consortia. Processing algorithms incorporated techniques from SAR interferometry literature developed at California Institute of Technology, Stanford University, and University of Delft. Data distribution was coordinated through portals maintained by USGS EarthExplorer, NASA Earthdata, and mirror sites at European Space Agency archives. Quality assessment referenced standards from International Organization for Standardization and validation studies published by teams at University of California, Berkeley, University of Colorado Boulder, and ETH Zurich.

Scientific and practical applications

SRTM-derived DEMs enabled advances in geomorphology studies at institutions like Smithsonian Institution and Natural History Museum, London, flood modeling used by World Bank and United Nations Development Programme, and seismic hazard analyses by United States Geological Survey and Japan Meteorological Agency. Urban planners at New York City Department of City Planning and infrastructure agencies in Brazil applied SRTM data for road network design and landslide risk assessment, while conservation groups such as World Wildlife Fund and Conservation International used elevation models for habitat mapping. Climate researchers at National Center for Atmospheric Research and NOAA integrated SRTM topography into regional climate models like HadGEM and CMIP experiments. SRTM products also supported archeological surveys by teams from University of Cambridge and University of Oxford and navigation enhancements for International Maritime Organization charting.

Mission results and legacy

The mission produced near-global elevation coverage that became a foundational geospatial layer used by Google, Microsoft mapping platforms, and numerous academic projects at Harvard University and Princeton University. Follow-on initiatives and missions influenced by SRTM include ASTER, TanDEM-X, and proposals for enhanced interferometric mapping under CEOS coordination. The data accelerated research published in journals like Science, Nature, and Journal of Geophysical Research and informed policy work at United Nations Environment Programme and Intergovernmental Panel on Climate Change. Long-term legacy includes democratization of elevation data enabling projects by OpenStreetMap and citizen science platforms, ongoing reprocessing efforts by USGS and NASA to integrate newer datasets, and a sustained impact on disciplines represented at universities and agencies worldwide.

Category:Earth observation satellites