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Written by Leandro Gonzalez
Jointly managed by NASA and USGS
The Landsat program, started in 1972, is one of the mainstays of NASA's earth-observation program. LDCM will be the first satellite of the Landsat family to be launched (estimated January 2013) since April 15, 1999. The Landsat satellites were designed to be of use to a variety of fields like forestry, agriculture, geology, and land-use planning, and the choice of spectral bands for the Landsat satellites was geared toward discriminating different types and amounts of vegetation. Landsat's strengths are generally seen to be it's regular acquisition schedule (revisits each spot on the earth every 16 days), long-term data archive (image with comparable specifications is available from 1982), and relatively rich spectral information (not as rich as hyperspectral data, but more bands than most high-resolution satellites like Ikonos or Quickbird). Limitations of Landsat data include its moderate spatial resolution (30m multispectral data, 15m panchromatic), and the fixed acquisition schedule that makes it difficult to acquire imagery for a particular place at a particular time (especially if clouds or smoke occur frequently over the area of interest).
It is estimated that Landsat Data Continuity Mission (LDCM) will acquire about 400 scenes daily. The images will be stored and processed to Level-1 products by USGS, consistent with current standard Landsat data products. The U. S. Geological Survey will make LDCM scenes available for download at no cost within 24 hours of reception and archiving.
The LDCM satellite will carry two pushbroom sensors: Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS).
Landsat Thematic Mapper 4 and 5 (TM4 and TM5), Landsat Enhanced Thematic Mapper 7 (TM7), ASTER - Advanced Spaceborne Thermal Emission and Reflection Radiometer
LDCM TIRS has two bands that cover the thermal infrared region of the electromagnetic spectrum. A second sensor (LDCM OLI) located in the same satellite along with the LDCM TIRS sensor contains eight bands (plus a panchromatic band) that cover the visible, near infrared, and short-wave infrared regions of the electromagnetic spectrum. The Landsat satellites were designed to be broadly applicable to fields like forestry, geology, agriculture, and regional planning, so the band locations and widths were picked to be sensitive to changes in vegetation and land cover.
Landsat Data Continuity Mission will revisit the same spot on the earth every 16 days.
The Landsat Data Continuity Mission satellite is set to be launched on January 2013.
Landsat Data Continuity Mission imagery will be available at no cost. The following sources will contain Landsat Data Continuity Mission imagery available to be downloaded: the USGS Global Visualization Viewer GLOVIS, the USGS Earth Explorer, or Landsat.org
The TIRS will capture data in two longwave thermal bands with a minimum of 100-meter resolution, but will be registered to and delivered with the OLI data product. Through USGS users can also acquire LDCM TIRS imagery resampled to 30-meter resolution to match the spatial resolution of the OLI sensor multispectral bands.
Format and delivery options for Landsat Data Continuity Mission imagery vary with where you order and download the imagery. Images are commonly shipped as GeoTIFF image files - one image for each band.
Landsat imagery is one of the most ubiquitous satellite image types, and a lot of effort has gone into making it easy to access and use. For the most part, Landsat imagery can be used in ArcGIS or other GIS applications without any special processing. Most Landsat images obtained either through USGS or another provider are distributed in GeoTIFF image format with one band per file. For the purposes of making it easier to handle, manipulate, and display the imagery, most people combine all of the separate image bands into a single, multi-band image file using an image-processing package like ENVI or ERDAS Imagine.
Landsat images are not terribly big or difficult to process by today's computing standards. In a GeoTIFF image format, the file for a single 30m band is approximately 53MB. As long as you are dealing with a study area that is contained within one or a few Landsat scenes, you should not need any special computer hardware to be able to use Landsat imagery.
• NASA Landsat Mission site - general information on the Landsat mission
• USGS Landsat Mission site - general information on the Landsat mission
• Landsat.org - Third-party site for ordering and downloading Landsat imagery
• Landsat Data Continuity Mission - general information on the LDCM sensors
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