For our purposes we will begin the history of remote sensing with the invention ofthe photographic camera in the early nineteenth century. In the 1840s photographs were taken from cameras secured to tethered balloons for purposes of topographic mapping. For the next 100 years or so camera technology improved but the major advances were in the platforms used to hold the camera systems. At first people experimented with platforms such as kites, rockets, and even pigeons. A major step forward was made with the invention ofthe airplane and the next leap occurred when cameras could be mounted on satellites, which provided a very stable and, of course, high-altitude platform. Satellites also provide an ideal platform for acquiring systematic data from around the globe which has proved invaluable for large area ecological modeling.
By the 1940s instrument research was also becoming increasingly sophisticated, pushing remote-sensing technology beyond visible-spectrum photography into infrared detection and radar systems. Leveraging this research, in 1972 the National Aeronautics and Space Administration (NASA) began the Landsat program with the launch of the Earth Resources Technology Satellite 1 (ERTS 1), which was later renamed Landsat 1. The Landsat program is now the longest running program of satellite remote sensing focused on EO. Following the launch of Landsat 1 other satellites were launched carrying different types of instruments such as radar, lidar, and more precise optical sensors. Satellite remote sensing has evolved to the point where most environmental systems (hydrologic, atmospheric, ecosystems) now have dedicated satellite instruments recording information to help us better monitor and manage Earth's environments, and providing valuable data for use in ecological modeling. For example, NASA's Earth Observing System (EOS) is a mission that includes the acquisition of satellite-based observations, science, and a data system to support the study of the land surface, biosphere, solid Earth, atmosphere, and oceans. One sensor in particular from the EOS mission that offers a broad range of image products of interest to ecologists is the Moderate Resolution Imaging Spectroradiometer (MODIS). Advances in satellite/instrument packages will continue to be made providing more precise and accurate data that can be used for ecological modeling.
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