LANDSAT-1 - http://www.satimagingcorp.com/gallery... - was the world's first earth observation satellite (EOS), launched by the United States in 1972. It is recognized for its ability to observe the earth far from space. Its excellent set of capabilities emphasized the importance of state-of-the-art remote sensing. Following LANDSAT-1, LANDSAT-2, 3, 4, 5, and 7 were launched. LANDSAT-7 is currently operated as a primary satellite.
LANDSAT-5 was equipped with a multispectral scanner (MSS) and thematic mapper (TM). MSS is an optical sensor designed to observe solar radiation, which is reflected from the Earth's surface in four different spectral bands, using a combination of the optical system and the sensor. TM is a more advanced version of the observation equipment used in the MSS, which observes the Earth's surface in seven spectral bands that range from visible to thermal infrared regions.
The thematic mapper (TM) is an advanced, multispectral scanning, earth resources sensor designed to achieve higher image resolution, sharper spectral separation, improved geometric fidelity, and greater radiometric accuracy and resolution than that of the MSS sensor. This sensor also images a swath that is 185 km (115 miles) wide, but each pixel in a TM scene represents a 30 m x 30 m ground area, except in the case of the far-infrared band 7, which uses a larger 120 m x 120 m pixel. The TM sensor has seven bands that simultaneously record reflected or emitted radiation from the Earth's surface in the blue-green (band 1), green (band 2), red (band 3), near-infrared (band 4), mid-infrared (bands 5 and 7), and the far-infrared (band 6) portions of the electromagnetic spectrum. TM band 2 can detect green reflectance from healthy vegetation, and band 3 is designed for detecting chlorophyll absorption in vegetation. TM band 4 is ideal for near-infrared reflectance peaks in healthy green vegetation, and for detecting water-land interfaces. TM band 1 can penetrate water for bathymetric (water depth) mapping along coastal areas, and is useful for soil-vegetation differentiation, as well as distinguishing forest types. The two mid-infrared bands on TM are useful for vegetation and soil moisture studies, and discriminating between rock and mineral types. The far-infrared band on TM is designed to assist in thermal mapping, and for soil moisture and vegetation studies.
The LANDSAT-7 satellite was successfully launched from Vandenburg Air Force Base on April 15, 1999. LANDSAT-7 is a 5,000 pound-class satellite, designed for a 705 km, sun-synchronous, earth mapping orbit with a 16-day repeat cycle. The payload is a single nadir-pointing instrument, the Enhanced Thematic Mapper Plus (ETM+). S-Band is used for commanding and housekeeping telemetry operations, while X-Band is used for instrument data downlink. A 378 gigabit solid state recorder (SSR) can hold 42 minutes of instrument data and 29 hours of housekeeping telemetry concurrently.
LANDSAT-7 is equipped with Enhanced Thematic Mapper Plus (ETM+), the successor of TM. The observation bands are essentially the same seven bands as TM, and the newly added panchromatic band 8, with a high resolution of 15m was added. An instrument malfunction occurred on May 31, 2003, with the result that all Landsat 7 scenes acquired since July 14, 2003 have been collected in "SLC-off" mode
