Earth observation satellite

Earth observation satellites are satellites specifically designed from orbit to Earth observation. Fields of application are mainly with weather satellite meteorology, environmental satellite for environmental monitoring, mapping, geology, etc. Technically, spy satellites a subset, however, the term is associated with an Earth observation satellite for civilian use. In the construction of remote-sensing satellites, a distinction the platform ( satellite bus ) and the instruments.

History

The first aerial photographs were taken in 1858 by Nadar. 1904 Alfred Maul get first aerial photographs with a photo rocket. (see also: History of Aerial Photography and History of Remote Sensing )

The first ( military ) earth observation satellites were in 1959 Keyhole satellites of the Corona program. On August 10, 1960, the first successful flight of a Discoverer satellite ( Corona program) took place. On April 1, 1960 began with TIROS - 1, the first experimental weather satellite. With Landsat -1 digital data acquisition by the MSS ( Multispectral Scanner ) was introduced in 1972. 1975 was used to GEOS - 3, the first radar altimeter. The Seasat mission in 1978 tested the Synthetic Aperture Radar and a scatterometer. Specially designed for the observation of the color of the oceans was the Multispektrallinienscanner Coastal Zone Color Scanner on Nimbus -7, the first environmental monitoring satellites. Successor of this instrument are SeaWiFS and MODIS on Aqua. Also MERIS Envisat has same research tasks.

Instruments (selection)

The Earth observation satellite work with both passive and active sensors. Passive measurement methods are so called because the light emitted by the earth and the clouds of light or heat energy is measured. The passive sensors mainly include optical sensors. In addition to visible light, they take on different spectral (IR, UV). The so-called atmospheric windows are used; These are wavelength regions in which the transmittance of the atmosphere is very large.

Another important method of measurement is the active remote sensing by radar ( lidar, etc.). It provides accurate values ​​for the surface of the earth. The measurement accuracy is close to the range of a few centimeters, thus making it possible to measure slightest ground movement. The advantage of this method is the Unabhängigsein of any existing cloudiness ( radar beams pass through it unaffected ). Using this active radar data can generate 3-D models of the earth's surface.

  • Lidar: Lidar In -space Technology Experiment ( LITE) - Space Shuttle 1994: first demonstration of the possibilities to observe aerosols and clouds from space, CALIPSO first satellite with lidar
  • Spectrometer: multispectral (up to 15 channels) and hyperspectral scanners ( approximately 15 to 200 spectral bands )
  • Scatterometer ( scatterometer ): study of air movement (wind speed and direction over ocean surfaces )
  • Synthetic aperture radar (SAR )
  • Laser altimeter
  • Mikrowellenaltimeter ( altimeter): Remote sensing of the sea surface
Corona (satellite) Television Infrared Observation Satellite Nimbus program List of Earth observation satellites
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