Earth observation satellite
Earth observation satellites or Earth remote sensing satellites are satellites specifically designed for Earth observation from orbit, similar to spy satellites but intended for non-military uses such as environmental monitoring, meteorology, map making etc. 
The first occurrence of satellite remote sensing can be dated to the launch of the first artificial satellite, Sputnik 1, by the Soviet Union on October 4, 1957. Sputnik 1 sent back radio signals, which scientists used to study the ionosphere.
NASA launched the first American satellite, Explorer 1, in January 31, 1958. The information sent back from its radiation detector led to the discovery of the Earth's Van Allen radiation belts.
The TIROS-1 spacecraft, launched on April 1, 1960 as part of NASA's TIROS (Television Infrared Observation Satellite) Program, sent back the first television footage of weather patterns to be taken from space.
, more than 150 Earth observation satellites were in orbit, recording data with both passive and active sensors and acquiring more than 10 terabits of data daily.
Mary Sherman Morgan
In 1957, the Russian Soviet Union and the United States had set a goal of placing satellites into Earth orbit as part of a worldwide scientific celebration known as the International Geophysical Year. In this endeavor the United States effort was called Project Vanguard. The Soviet Union successfully launched the Sputnik satellite on October 4, 1957, an event followed soon after by a very public and disastrous explosion of a Vanguard rocket. Political pressure forced U.S. politicians to allow a former German rocket scientist, Wernher von Braun, to prepare his Jupiter C rocket for an orbital flight. In the renamed launcher (now called Juno I) the propellant succeeded in launching America’s first satellite, Explorer I, into orbit on January 31, 1958.