One hundred and two years after cameras were first flown on balloons to get a better
look at Earth, the U.S. launched the first weather satellite, the Television and Infrared
Observation Satellite (TIROS-1). TIROS-1 made it possible for the first time to monitor
weather conditions over most of the world regularly, including the approximately 70%
of the Earth covered by water (where weather observations had been sparse or non-
existent). That first launch on April 1, 1960 was the beginning of what is now a sophis-
ticated network of international environmental satellites monitoring Earth. Regional,
national, and global observations provide information with immediate impact—such as
identifying hurricanes or winter storms—and providing data for climatic and global
change studies—such as changes in polar ice or mean sea level.
Satellites are now operated to fulfill a variety of objectives (e.g., communications, Earth
observation, planetary exploration). However, the focus of this publication is on envi-
ronmental (also called meteorological or weather) satellites, and their unique capability
to provide direct readout—that is, they provide data that can be obtained directly from
the satellite by a ground station user.