A variety of probes has been devloped to explore the moon, ranging from spacecrafts that fly-by moon, impact lunar surface, circumlunar probe, or soft landers.
Between October to December 1958, the United States made 3 attempts to approach the moon with the Pioneer rockets, two of which traveled less than a third of the required distance.
Just after launch on 11 October 1958, the rocket's second and third stage failed to separate evenly. As a result, Pioneer 1 was unable to achieve a lunar trajectory. However, it did manage to returned data on the Van Allen Belt and micrometeorite impacts before re-entering earth's atmosphere on 12 October 1958.
Launched on 8 November 1958, the second stage of the Pioneer 2 rocket failed to ignite, causing the the spacecraft crashed back to earth.
Launched in early December 1958, the Pioneer 3 rocket's first stage shut off too early, causing the spacecraft to crash.
The first successful lunar spacecraft was the Soviet Union Luna 1 (or Mechta), placed on a fly-by trajectory in January 1959.
Launched on 2 January 1959, Luna 1 missed the moon and went into a solar orbit. However, the spacecraft did provide some scientific data when it released a sodium vapor cloud 70,000 miles from earth that allowed scientists to study interplanetary gases.
The United States followed Luna 1 in March 1959 with its Pioneer 4 fly-by spacecraft.
Launched on 3 March 1959, Pioneer 4 passed within 60,000 kilometers (37,300 miles) of the moon, returned data on lunar radiation levels, then entered a solar orbit.
In September 1959, the Soviet Union responded by becoming the first to place an object on the moon when they struck the lunar surface with their Luna 2.
Launched on 12 September 1959 and impact moon on 14 September 1959, Luna 2 was the first spacecraft to land on another celestial body. The spacecraft impacted on the moon's surface just east of the Sea of Serenity near the craters Aristides, Archimedes, and Autolycus. The spacecraft did not detect a magnetic field around the moon.