The LANDSAT program consists of a series of optical/infrared remote sensing satellites for land observation. The program was first started by The National Aeronautics and Space Administration (NASA) in 1972, then turned over to the National Oceanic and Atmospheric Administration (NOAA) after it became operational. Since 1984, satellite operation and data handling were managed by a commercial company EOSAT. However, all data older than 2 years return to "public domain" and are distributed by the Earth Resource Observation System (EROS) Data Center of the US Geological Servey (USGS).

The first satellite in the series, LANDSAT-1 (initially named as the Earth Resource Technology Satellite ERTS-1) was launched on 23 July 1972. The satellite had a designed life expectancy of 1 year but it ceased operation only on January 1978. LANDSAT-2 was launched on 22 January 1975 and three additional LANDSAT satellites were launched in 1978, 1982, and 1984 (LANDSAT-3, 4, and 5 respectively). LANDSAT-6 was launched on October 1993 but the satellite failed to obtain orbit. A new satellite LANDSAT-7 was launched in 15 April 1999. Currently, only LANDSAT-5 and 7 are operational .

Sensors

• MSS (Multi-Spectral Scanner), on LANDSAT-1 to 5. Being one of the older generation sensors, routine data acquisition for MSS was terminated in late 1992. The resolution of the MSS sensor was approximately 80 m with radiometric coverage in four spectral bands from the visible green to the near-infrared (IR) wavelengths. Only the MSS sensor on Landsat 3 had a fifth band in the thermal-IR.

• TM (Thematic Mapper), first operational on LANDSAT-4. TM sensors primarily detect reflected radiation from the Earth surface in the visible and near-infrared (IR) wavelengths, but the TM sensor provides more radiometric information than the MSS sensor. The wavelength range for the TM sensor is from the visible (blue), through the mid-IR, into the thermal-IR portion of the electromagnetic spectrum. Sixteen detectors for the visible and mid-IR wavelength bands in the TM sensor provide 16 scan lines on each active scan. Four detectors for the thermal-IR band provide four scan lines on each active scan. The TM sensor has a spatial resolution of 30 m for the visible, near-IR, and mid-IR wavelengths and a spatial resolution of 120 m for the thermal-IR band.

• ETM+ (Enhanced Thematic Mapper Plus), is carried on board Landsat 7. The ETM+ instrument is an eight-band multispectral scanning radiometer capable of providing high-resolution image information of the Earths surface. Its spectral bands are similar to thoss of TM, except that the thermal band (band 6) has an improved resolution of 60 m (versus 120 m in TM). There is also an additional panchromatic band at 15 m resolution.

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