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.
Marshall Space Flight Center
The Soviet Union launched Sputnik 1, the first man-made earth satellite, on October 4, 1957. This was followed on November 3 with the second satellite, Sputnik 2. The United States attempted a satellite launch on December 6, using the NRL's Vanguard rocket, but it barely struggled off the ground, then fell back and exploded. On January 31, 1958, after finally receiving permission to proceed, von Braun and the ABMA space development team used a Jupiter C in a Juno I configuration (addition of a fourth stage) to successfully place Explorer 1, the first American satellite, into orbit around the earth.