History of Satellite Remote Sensing
Remote sensing from space has developed in recent decades from an experimental application into a technology that we depend on for many aspects of earth and planetary research. Satellite sensing systems provide us with data critical to weather prediction, agricultural forecasting, resource exploration, and environmental monitoring.
Images were obtained from rocket-borne cameras as early as the 1890s, but the impetus for remote sensing from space really came following World War II and the development of rocket technology. The development of meteorological satellites in the early 1960s led research into atmospheric imaging, and the early manned space flights demonstrated the potential of orbiting cameras to provide information about the earth's surface.
Basics of Satellite Remote Sensing
Remote sensing systems, including simple photography, are based on the detection and documentation of electromagnetic radiation that is emitted or reflected by the earth's surface. The wavelength characteristics of electromagnetic radiation are a function of the temperature of the energy source (for instance, the sun), and can be detected by spectral sensors that are appropriately designed to receive the range of spectral values specific to that material.
This radiation "signal" can be detected by a variety of sensors, depending on which part of the electromagnetic spectrum it occupies. For example, the spectral signature of visible (to the human eye) light is typically recorded by black-and-white photographic film, while light in the near infrared and thermal infrared portions of the spectrum are recorded on color-infrared film and thermal scanners, respectively. Multispectral scanners record a wide range of electromagnetic energy, including ultraviolet, visible, infrared and thermal radiation, and are important components of many satellite remote sensing platforms.
Multispectral scanners (MSS) are sensors that detect emitted and reflected energy electronically, rather than photographically, with the electric signal being converted to digital form for image processing and interpretation. MSS generate an electrical signal that corresponds to energy (wavelength) variations in the scene, while photographs record these variations chemically on light-sensitive film. Multispectral (as opposed to color negative and black-and-white) images were first acquired during the Apollo program, and the first operational MSS was launched in 1972 on a modified Nimbus weather satellite. This heralded the beginning of the Landsat Program (initially designated ERTS - Earth Resources Technology Satellites).
Past, Current, and Future Earth Observation Satellites
Specifications of Past, Current, and Future Earth Observation Satellites (Information provided by Environmental Remote Sensing Center (ERSC) at University of Wisconsin-Madison.)
• Future Satellites
• Current Satellites
• Past Satellites
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