The Shuttle Radar Topography Mission (SRTM) was flown aboard the space shuttle Endeavour February 11-22, 2000. The National Aeronautics and Space Administration (NASA) and the National Geospatial-Intelligence Agency (NGA) participated in an international project to acquire radar data which were used to create the first near-global set of land elevations. The radars used during the SRTM mission were actually developed and flown on two Endeavour missions in 1994. The C-band Spaceborne Imaging Radar and the X-Band Synthetic Aperture Radar (X-SAR) hardware were used on board the space shuttle in April and October 1994 to gather data about Earth's environment. The technology was modified for the SRTM mission to collect interferometric radar, which compared two radar images or signals taken at slightly different angles. This mission used single-pass interferometry, which acquired two signals at the same time by using two different radar antennas. An antenna located on board the space shuttle collected one data set and the other data set was collected by an antenna located at the end of a 60-meter mast that extended from the shuttle. Differences between the two signals allowed for the calculation of surface elevation. Endeavour orbited Earth 16 times each day during the 11-day mission, completing 176 orbits. SRTM successfully collected radar data over 80% of the Earth's land surface between 60° north and 56° south latitude with data points posted every 1 arc-second (approximately 30 meters). Two resolutions of finished grade SRTM data are available through EarthExplorer from the collection held in the USGS EROS archive: 1 arc-second (approximately 30-meter) high resolution elevation data offer worldwide coverage of void filled data at a resolution of 1 arc-second (30 meters) and provide open distribution of this high-resolution global data set. Some tiles may still contain voids. The SRTM 1 Arc-Second Global (30 meters) data set will be released in phases starting September 24, 2014. Users should check the coverage map in EarthExplorer to verify if their area of interest is available. 3 arc-second (approximately 90-meter) medium resolution elevation data are available for global coverage. The 3 arc-second data were resampled using cubic convolution interpolation for regions between 60° north and 56° south latitude. [Summary provided by the USGS.]

The Shuttle Radar Topography Mission (SRTM) successfully collected Interferometric Synthetic Aperture Radar (IFSAR) data over 80 percent of the landmass of the Earth between 60 degrees North and 56 degrees South latitudes in February 2000. The mission was co-sponsored by the National Aeronautics and Space Administration (NASA) and National Geospatial-Intelligence Agency (NGA). NASA's Jet Propulsion Laboratory (JPL) performed preliminary processing of SRTM data and forwarded partially finished data directly to NGA for finishing by NGA's contractors and subsequent monthly deliveries to the NGA Digital Products Data Wharehouse (DPDW). All the data products delivered by the contractors conform to the NGA SRTM products and the NGA Digital Terrain Elevation Data (DTED) to the Earth Resources Observation & Science (EROS) Center. The DPDW ingests the SRTM data products, checks them for formatting errors, loads the SRTM DTED into the NGA data distribution system, and ships the public domain SRTM DTED to the U.S. Geological Survey (USGS) Earth Resources Observation & Science (EROS) Center. Two resolutions of finished grade SRTM data are available through EarthExplorer from the collection held in the USGS EROS archive: 1 arc-second (approximately 30-meter) high resolution elevation data are only available for the United States. 3 arc-second (approximately 90-meter) medium resolution elevation data are available for global coverage. The 3 arc-second data were resampled using cubic convolution interpolation for regions between 60° north and 56° south latitude. [Summary provided by the USGS.]

Culminating more than four years of processing data, NASA and the National Geospatial-Intelligence Agency (NGA) have completed Earth's most extensive global topographic map. The mission is a collaboration among NASA, NGA, and the German and Italian space agencies. For 11 days in February 2000, the space shuttle Endeavour conducted the Shuttle Radar Topography Mission (SRTM) using C-Band and X-Band interferometric synthetic aperture radars to acquire topographic data over 80% of the Earth's land mass, creating the first-ever near-global data set of land elevations. This data was used to produce topographic maps (digital elevation maps) 30 times as precise as the best global maps used today. The SRTM system gathered data at the rate of 40,000 per minute over land. They reveal for the first time large, detailed swaths of Earth's topography previously obscured by persistent cloudiness. The data will benefit scientists, engineers, government agencies and the public with an ever-growing array of uses. The SRTM radar system mapped Earth from 56 degrees south to 60 degrees north of the equator. The resolution of the publicly available data is three arc-seconds (1/1,200th of a degree of latitude and longitude, about 295 feet, at Earth's equator). The final data release covers Australia and New Zealand in unprecedented uniform detail. It also covers more than 1,000 islands comprising much of Polynesia and Melanesia in the South Pacific, as well as islands in the South Indian and Atlantic oceans. SRTM data are being used for applications ranging from land use planning to "virtual" Earth exploration. Currently, the mission's homepage "http://www.jpl.nasa.gov/srtm" provides direct access to recently obtained earth images. The Shuttle Radar Topography Mission C-band data for North America and South America are available to the public. A list of complete public data set is available at "http://www2.jpl.nasa.gov/srtm/dataprod.htm" The data specifications are within the following parameters: 30-meter X 30-meter spatial sampling with 16 meter absolute vertical height accuracy, 10-meter relative vertical height accuracy, and 20-meter absolute horizontal circular accuracy. From the JPL Mission Products Summary, "http://www.jpl.nasa.gov/srtm/dataprelimdescriptions.html". The primary products of the SRTM mission are the digital elevation maps of most of the Earth's surface. Visualized images of these maps are available for viewing online. Below you will find descriptions of the types of images that are being generated: - Radar Image - Radar Image with Color as Height - Radar Image with Color Wrapped Fringes -Shaded Relief - Perspective View with B/W Radar Image Overlaid - Perspective View with Radar Image Overlaid, Color as Height - Perspective View of Shaded Relief - Perspective View with Landsat or other Image Overlaid - Contour Map - B/W with Contour Lines - Stereo Pair - Anaglypgh The SRTM radar contained two types of antenna panels, C-band and X-band. The near-global topographic maps of Earth called Digital Elevation Models (DEMs) are made from the C-band radar data. These data were processed at the Jet Propulsion Laboratory and are being distributed through the United States Geological Survey's EROS Data Center. Data from the X-band radar are used to create slightly higher resolution DEMs but without the global coverage of the C-band radar. The SRTM X-band radar data are being processed and distributed by the German Aerospace Center, DLR.

The SRTMUS1 collection was retired on November 20, 2014, when global SRTM data became available at a resolution of 1 arc second. The data for the United States are included in the [SRTMGL1](https://doi.org/10.5067/MEaSUREs/SRTM/SRTMGL1.003) dataset.The Land Processes Distributed Active Archive Center (LP DAAC) is responsible for the archive and distribution of the NASA Making Earth System Data Records for Use in Research Environments ([MEaSUREs](https://earthdata.nasa.gov/about/competitive-programs/measures)) version SRTM, which includes the United States 1 arc second (~30 meter) product.NASA Shuttle Radar Topography Mission (SRTM) datasets result from a collaborative effort by the National Aeronautics and Space Administration (NASA) and the National Geospatial-Intelligence Agency (NGA - previously known as the National Imagery and Mapping Agency, or NIMA), as well as the participation of the German and Italian space agencies. The purpose of SRTM was to generate a near-global digital elevation model (DEM) of the Earth using radar interferometry. SRTM was a primary component of the payload on the Space Shuttle Endeavour during its STS-99 mission. Endeavour launched February 11, 2000, and flew for 11 days.Each SRTMUS1 data tile contains a mosaic and blending of elevations generated by averaging all "data takes" that fall within that tile. These elevation files use the extension “.HGT”, meaning height (such as N37W105.SRTMUS1.HGT). The primary goal of creating the Version 3 data was to eliminate voids that were present in earlier versions of SRTM data. In areas with limited data, existing topographical data were used to supplement the SRTM data to fill the voids. The source of each elevation pixel is identified in the corresponding [SRTMUS1N](http://doi.org/10.5067/MEaSUREs/SRTM/SRTMUS1N.003) product (such as N37W105.SRTMUS1N.NUM).SRTM collected data in swaths, which extend from ~30 degrees off-nadir to ~58 degrees off-nadir from an altitude of 233 kilometers (km). These swaths are ~225 km wide and consisted of all land between 60 degrees N and 56 degrees S latitude. This accounts for about 80% of Earth’s total landmass.Known Issues* Known issues in the NASA SRTM are described in the following publication:Rodriguez, E., C. S. Morris, and J. E. Belz (2006), A global assessment of the SRTM performance, Photogramm. Eng. Remote Sens., 72, 249–260. https://doi.org/10.14358/PERS.72.3.249Improvements/Changes from Previous Version* Voids in the Version 3.0 products have been filled with ASTER Global Digital Elevation Model (GDEM) Version 2.0, the Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010), and the National Elevation Dataset (NED).

The SRTMUS1N collection was retired on November 20, 2014, when global SRTM data became available at a resolution of 1 arc second. The data for the United States are included in the [SRTMGL1N](https://doi.org/10.5067/MEaSUREs/SRTM/SRTMGL1N.003) dataset.The Land Processes Distributed Active Archive Center (LP DAAC) is responsible for the archive and distribution of NASA Making Earth System Data Records for Use in Research Environments ([MEaSUREs](https://www.earthdata.nasa.gov/about/competitive-programs/measures)) Shuttle Radar Topography Mission (SRTM), which includes the United States 1 arc second (~30 meter) number product. Ancillary one-byte (0 to 255) “NUM” (number) files were produced for NASA SRTM Version 3. These files have names corresponding to the elevation files, except with the extension “.NUM” (such as N37W105.NUM). The elevation files use the extension “.HGT”, meaning height (such as N37W105.HGT). The separate NUM file indicates the source of each DEM pixel; the number of ASTER scenes used (up to 100), if ASTER; and the number of SRTM data takes (up to 24), if SRTM. The NUM file for both 3 arc second products (whether sampled or averaged) references the 3 x 3 center pixel. The NASA SRTM data sets result from a collaborative effort by the National Aeronautics and Space Administration (NASA) and the National Geospatial-Intelligence Agency (NGA - previously known as the National Imagery and Mapping Agency, or NIMA), as well as the participation of the German and Italian space agencies. This collaboration aims to generate a near-global digital elevation model (DEM) of Earth using radar interferometry. SRTM was the primary (and virtually only) payload on the STS-99 mission of the Space Shuttle Endeavour, which launched February 11, 2000 and flew for 11 days.The SRTM swaths extended from ~30 degrees off-nadir to ~58 degrees off-nadir from an altitude of 233 kilometers (km), creating swaths ~225 km wide, and consisted of all land between 60 degrees N and 56 degrees S latitude to account for 80% of Earth’s total landmass.Known Issues* Known issues in the NASA SRTM are described in the following publication:Rodriguez, E., C. S. Morris, and J. E. Belz (2006), A global assessment of the SRTM performance, Photogramm. Eng. Remote Sens., 72, 249–260. https://doi.org/10.14358/PERS.72.3.249Improvements/Changes from Previous Version* Voids in the Version 3.0 products have been filled with ASTER Global Digital Elevation Model (GDEM) Version 2.0, the Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010), and the National Elevation Dataset (NED).

CER_GEO_Ed4_MTS02_SH_V01 is the Satellite Cloud and Radiation Property retrieval System (SatCORPS) Clouds and the Earth's Radiant Energy System (CERES) Geostationary Satellite (GEO) Edition 4 Multi-functional Transport Satellite 2 Replacement (MTSAT-2R) over the Southern Hemisphere (SH) Version 1.0 data product. Data was collected using the Visible and Infrared Spin Scan Radiometer (VISSR) Instrument on The Multi-functional Transport Satellite 2 (MTSAT-2) platform. This data set comprises cloud micro-physical and radiation properties derived hourly from MTSAT-2 geostationary satellite imager data using the Langley Research Center (LARC) SATCORPS algorithms supporting the CERES project. Each active geostationary satellite's cloud microphysical and radiation properties are merged to create hourly global cloud properties that estimate fluxes between CERES instrument measurements to account for the changing diurnal cycle. The data set is arranged as files for each hour and in netCDF-4 format. The observations are at 4 km resolution (at nadir) and are sub-sampled to 8 km. CERES is a key Earth Observing System (EOS) program component. The CERES instruments provide radiometric measurements of the Earth's atmosphere from three broadband channels. The CERES missions follow the successful Earth Radiation Budget Experiment (ERBE) mission. The first CERES instrument, the proto flight model (PFM), was launched on November 27, 1997, as part of the Tropical Rainfall Measuring Mission (TRMM). Two CERES instruments (FM1 and FM2) were launched into polar orbit onboard the Earth Observing System (EOS) flagship Terra on December 18, 1999. Two additional CERES instruments (FM3 and FM4) were launched onboard Earth Observing System (EOS) Aqua on May 4, 2002. The CERES FM5 instrument was launched onboard the Suomi National Polar-orbiting Partnership (NPP) satellite on October 28, 2011. The newest CERES instrument (FM6) was launched onboard the Joint Polar-Orbiting Satellite System 1 (JPSS-1) satellite, now called NOAA-20, on November 18, 2017.

CER_GEO_Ed4_MTS02_SH_V01.2 is the Satellite Cloud and Radiation Property retrieval System (SatCORPS) Clouds and the Earth's Radiant Energy System (CERES) Geostationary Satellite (GEO) Edition 4 Multi-functional Transport Satellite 2 Replacement (MTSAT-2R) over the Southern Hemisphere (SH) Version 1.2 data product. Data was collected using the Visible and Infrared Spin Scan Radiometer (VISSR) Instrument on the Multi-functional Transport Satellite 2 (MTSAT-2) platform. Data collection for this product is in progress. Note: Version 1.2 is identical to version 1.0. No changes in the retrieval algorithm. This data set comprises cloud micro-physical and radiation properties derived hourly from MTSAT-2 geostationary satellite imager data using the Langley Research Center (LARC) SATCORPS algorithms supporting the CERES project. Each active geostationary satellite's cloud micro-physical and radiation properties are merged to create hourly global cloud properties that estimate fluxes between CERES instrument measurements to account for the changing diurnal cycle. The data set is arranged as files for each hour and in netCDF-4 format. The observations are at 4 km resolution (at nadir) and are sub-sampled to 8 km. CERES is a key Earth Observing System (EOS) program component. The CERES instruments provide radiometric measurements of the Earth's atmosphere from three broadband channels. The CERES missions follow the successful Earth Radiation Budget Experiment (ERBE) mission. The first CERES instrument, the protoflight model (PFM), was launched on November 27, 1997, as part of the Tropical Rainfall Measuring Mission (TRMM). Two CERES instruments (FM1 and FM2) were launched into polar orbit on board the Earth Observing System (EOS) flagship Terra on December 18, 1999. Two additional CERES instruments (FM3 and FM4) were launched on board Earth Observing System (EOS) Aqua on May 4, 2002. The CERES FM5 instrument was launched on board the Suomi National Polar-orbiting Partnership (NPP) satellite on October 28, 2011. The newest CERES instrument (FM6) was launched on board the Joint Polar-Orbiting Satellite System 1 (JPSS-1) satellite, now called NOAA-20, on November 18, 2017.

The Land Processes Distributed Active Archive Center (LP DAAC) is responsible for the archive and distribution of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs (https://earthdata.nasa.gov/about/competitive-programs/measures)) version SRTM, which includes the global 1 arc second (~30 meter) product. NASA Shuttle Radar Topography Mission (SRTM) datasets result from a collaborative effort by the National Aeronautics and Space Administration (NASA) and the National Geospatial-Intelligence Agency (NGA - previously known as the National Imagery and Mapping Agency, or NIMA), as well as the participation of the German and Italian space agencies. The purpose of SRTM was to generate a near-global digital elevation model (DEM) of the Earth using radar interferometry. SRTM was a primary component of the payload on the Space Shuttle Endeavour during its STS-99 mission. Endeavour launched February 11, 2000, and flew for 11 days. SRTM collected data in swaths, which extend from ~30 degrees off-nadir to ~58 degrees off-nadir from an altitude of 233 kilometers (km). These swaths are ~225 km wide, and consisted of all land between 60 degrees N and 56 degrees S latitude. This accounts for about 80 percent of Earth’s total landmass. Each SRTMGL1 data tile contains a mosaic and blending of elevations generated by averaging all "data takes" that fall within that tile. These elevation files use the extension “.HGT”, meaning height (such as N37W105.SRTMGL1.HGT). The primary goal of creating the Version 3 data was to eliminate voids that were present in earlier versions of SRTM data. In areas with limited data, existing topographical data were used to supplement the SRTM data to fill the voids. The source of each elevation pixel is identified in the corresponding SRTMGL1N (https://doi.org/10.5067/MEaSUREs/SRTM/SRTMGL1N.003) product (such as N37W105.SRTMGL1N.NUM). The global 1 arc second SRTM product is also available in NetCDF4 format as the SRTMGL1_NC dataset with the source of each elevation pixel in the corresponding SRTMGL1_NUMNC product. Known Issues * Known issues in the NASA SRTM are described in the following publication: Rodriguez, E., C. S. Morris, and J. E. Belz (2006), A global assessment of the SRTM performance, Photogramm. Eng. Remote Sens., 72, 249–260. https://doi.org/10.14358/PERS.72.3.249 Improvements/Changes from Previous Versions * Voids in the Version 3.0 products have been filled with ASTER Global Digital Elevation Model (GDEM) Version 2.0, the Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010), and the National Elevation Dataset (NED).

The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February of 2000. SRTM is an international project spearheaded by the National Geospatial-Intelligence Agency (NGA) and the National Aeronautics and Space Administration (NASA). Version 3: Elimination of the voids in the NASA SRTM DEM was the primary goal of a project under the NASA MEaSUREs (Making Earth System Data Records for Use in Research Environments) Program. Ultimately this was achieved by filling the voids with elevation data primarily from the ASTER GDEM2 (Global Digital Elevation Model Version 2) and secondarily from the USGS GMTED2010 elevation model or the USGS National Elevation Dataset (NED). For more information on this dataset visit the LP DAAC NASA Shuttle Radar Topography Mission Global 3 arc second page.

CER_GEO_Ed4_MTS02_NH_V01.2 is the Satellite ClOud and Radiation Property retrieval System (SatCORPS) Clouds and the Earth's Radiant Energy System (CERES) Geostationary Satellite (GEO) Edition 4 Multi-functional Transport Satellite 2 Replacement (MTSAT-2R) over the Northern Hemisphere (NH) Version 1.2 data product. Data was collected using the Visible and Infrared Spin Scan Radiometer (VISSR) Instrument on the The Multi-functional Transport Satellite 2 (MTSAT-2) platform. Data collection for this product is in progress. Note : Version 1.2 is identical to version 1.0 . No changes have been made to the retrieval algorithm. This data set is comprised of cloud micro-physical and radiation properties derived hourly from GOES-11 geostationary satellite imager data using the Langley Research Center (LaRC) SATCORPS algorithms in support of the CERES project. The cloud micro-physical and radiation properties from each active geostationary satellite are merged together to create hourly global cloud properties that are used to estimate fluxes between CERES instrument measurements to account for the changing diurnal cycle. The data set is arranged as files for each hour and in netCDF-4 format. The observations are at 4-km resolution (at nadir) and are sub-sampled to 8 km. CERES is a key component of the Earth Observing System (EOS) program. The CERES instruments provide radiometric measurements of the Earth's atmosphere from three broadband channels. The CERES missions are a follow-on to the successful Earth Radiation Budget Experiment (ERBE) mission. The first CERES instrument, protoflight model (PFM), was launched on November 27, 1997 as part of the Tropical Rainfall Measuring Mission (TRMM). Two CERES instruments (FM1 and FM2) were launched into polar orbit on board the Earth Observing System (EOS) flagship Terra on December 18, 1999. Two additional CERES instruments (FM3 and FM4) were launched on board Earth Observing System (EOS) Aqua on May 4, 2002. The CERES FM5 instrument was launched on board the Suomi National Polar-orbiting Partnership (NPP) satellite on October 28, 2011. The newest CERES instrument (FM6) was launched on board the Joint Polar-Orbiting Satellite System 1 (JPSS-1) satellite, now called NOAA-20, on November 18, 2017.