October 4, 1957 - Sputnik-1 - USSR
First artificial satellite.

1958 - Explorer I - USA
Successful launch atop Jupiter-C rocket. Instruments for monitoring cosmic rays and micrometoerites.
First to detect the trapped radiation in the Earth's atmosphere (Van Allen Radiation Bellt).

1958 - Explorer III - USA
Recorded complete history of the Earth's radiation belt.

1958 - Explorer IV - USA
Some of the instruments failed to operate.

August 17, 1958 - Pioneer 0 - USA Lunar Orbiter
First stage exploded.

October 11, 1958 - Pioneer 1 - USA Lunar Orbiter
Failed to reach escape velocity.

December 6, 1958 - Pioneer 3 - USA Lunar Flyby
Failed to reach escape velocity.

January 2, 1959 - Luna 1 - USSR Lunar Flyby - 361 kg
Luna 1 was the first lunar flyby. It discovered the solar wind and is now in a solar orbit.

March 3, 1959 - Pioneer 4 - USA Distant Lunar Flyby - 5.9 kg
Space probe is now in a solar orbit.

September 12, 1959 - Luna 2 - USSR Lunar Hard Lander - 387 kg
Luna 2 was the first spacecraft to impact the surface of the moon on September 14, 1959.

October 4, 1959 - Luna 3 - USSR Lunar Far Side Flyby - 278.5 kg
Encountered the Moon on October 7, 1959 and returned the first image of the Moon's hidden side.
Space probe is now in a decayed earth-moon orbit.

March 11, 1960 - Pioneer 5 - USA Solar Monitor
Space probe is now in a solar orbit.

October 10, 1960 - Mars 1960A - USSR Mars Probe
Failed to reach Earth orbit.

October 14, 1960 - Mars 1960B - USSR Mars Probe
Failed to reach Earth orbit.