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.
Redstone (rocket family)
Juno I was a derivative of the Jupiter-C, used to launch the first American satellite, Explorer 1, on January 31, 1958. Although the U.S. possibly could have put a satellite into orbit before the Soviet Union had the ABMA been allowed to attempt a satellite launch in August 1956, the Eisenhower administration wanted the first U.S. satellite to be launched by a civil rocket developed by American engineers instead of a rocket derived from a military missile program and developed by the German engineers of Operation Paperclip. Additionally, the administration saw value in the USSR taking the first move to reach orbit because they would set the precedent that territorial overflight in space was fair game, necessary for the United States' space-based photoreconaissance ambitions in the wake of diplomatic protests against U-2 incursions of Soviet airspace.