The first two decades of the Space Age were used to determine the capabilities of Earth-observing satellites.
Satellites for specific purposes, such as TIROS for weather, were largely piecemeal efforts. Only in the 1980s were steps taken toward a more comprehensive plan for studying the entire Earth system on a global scale. Following a number of studies, the NASA, in 1987, adopted a Mission to Planet Earth as one of its four overriding themes. The centerpiece of Mission to Planet Earth was to be the Earth Observing System.
After much rescoping and reshaping of the program, in 1999, Terra -- the first of three flagship polar-orbiting spacecraft -- was launched. It was followed by Aqua in 2002 and Aura in 2004.
Despite being subjected to the politics of climate change and global warming, these satellites and others are making significant contributions to Earth science.
Image: Hurricane Katrina -- closing in on the Mississippi-Louisiana coastline and the adjacent Gulf Coast forests on August 28, 2005 -- is photographed by the state-of-the-art instrument aboard NASA's Terra satellite.
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