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.
Kosmos 52
Kosmos 52 was launched by a Vostok-2 rocket, serial number R15002-03, flying from Site 31/6 at the Baikonur Cosmodrome. The launch took place at 09:36 UTC on 11 January 1965, with the spacecraft receiving its Kosmos designation - along with the International Designator 1965-001A and the Satellite Catalog Number 968 - upon its successful insertion into orbit. It was the first satellite to be launched in the year 1965.