Luna 1, First spacecraft to reach the moon

Luna 1: The first spacecraft to reach the moon, and (accidentally) the first spacecraft to achieve heliocentric orbit.

Designed as part of the Soviet Ye-1 series of spacecraft, the Luna 1 was the only of its sister ships to launch successfully. It also bore the name "Cosmic Rocket" because it was the first craft to achieve Earth escape velocity.

Luna 1 was meant to impact the moon, but a problem with guidance sent the little probe past its intended target and into heliocentric orbit. It's still out there today, drifting alone between the Earth and Mars.