1950s
| Satellite | Country | Date | Sponsor | Notes |
|---|---|---|---|---|
| Sputnik 2 | Soviet Union | 3 November 1957 | Korolev Design Bureau | Research charged particles near Earth |
| Explorer 1 | United States | 1 February 1958 | U.S. Army Ballistic Missile Agency | Decayed 31 May 1970. Discovered Van Allen belts. |
| Explorer 2 | United States | 5 March 1958 | U.S. Army Ballistic Missile Agency | Failed to orbit. |
| Vanguard I | United States | 17 March 1958 | U.S. Naval Research Laboratory | Oldest artificial satellite in orbit. |
| Explorer 3 | United States | 26 March 1958 | U.S. Army Ballistic Missile Agency | Decayed 28 June 1958. |
| Vanguard TV-5 | United States | 29 April 1958 | U.S. Naval Research Laboratory | Failed to orbit. |
| Sputnik 3 | Soviet Union | 15 May 1958 | Korolev Design Bureau | Decayed 6 April 1960. |
| Vanguard SLV-1 | United States | 28 May 1958 | U.S. Naval Research Laboratory | Failed to orbit. |
| Vanguard SLV-2 | United States | 26 June 1958 | U.S. Naval Research Laboratory | Failed to orbit. |
| Explorer 4 | United States | 26 July 1958 | U.S. DARPA | Measured electrons & protons in radiation belts. Also measured data on Operation Argus nuclear explosions. |
| Explorer 5 | United States | 24 August 1958 | U.S. DARPA | Failed to orbit. |
| Vanguard SLV-3 | United States | 26 September 1958 | U.S. Naval Research Laboratory | Failed to orbit. |
| Beacon 1 | United States | 23 October 1958 | NASA/U.S. Army | Failed to orbit. |
| Vanguard II | United States | 17 February 1959 | NASA/U.S. Naval Research Laboratory | Still in orbit. |
| Vanguard SLV-5 | United States | 14 April 1959 | NASA | Failed to orbit. |
| Vanguard SLV-6 | United States | 22 June 1959 | NASA | Failed to orbit. |
| Explorer S-1 | United States | 16 July 1959 | NASA | Failed to orbit. |
| Explorer 6 | United States | 7 August 1959 | Jet Propulsion Laboratory | Decayed 1 July 1961. |
| Beacon 2 | United States | 15 August 1959 | NASA/U.S. Navy | Failed to orbit. |
| Vanguard III | United States | 18 September 1959 | U.S. Naval Research Laboratory | Still in orbit. |
| Explorer 7 | United States | 13 October 1959 | NASA | Still in orbit. |
Read more about this topic: Timeline Of Earth Science Satellites