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.
SCORE (satellite)
Project SCORE (Signal Communications by Orbiting Relay Equipment) was the world's first purpose-built communications satellite. Launched aboard an American Atlas rocket on December 18, 1958, SCORE provided the second test of a communications relay system in space (the first having been provided by the USAF/NASA's Pioneer 1), the first broadcast of a human voice from space, and the first successful use of the Atlas as a launch vehicle. It captured world attention by broadcasting a Christmas message via shortwave radio from U.S. President Dwight D. Eisenhower through an on-board tape recorder. The satellite was popularly dubbed ""The Talking Atlas"". SCORE, as a geopolitical strategy, placed the United States at an even technological par with the Soviet Union as a highly functional response to the Sputnik 1 and Sputnik 2 satellites.