Pioneer 1: The first NASA spacecraft
Pioneer 1, launched on October 11, 1958, was the first successful NASA launch. It followed Pioneer 0, the first attempt by any nation at a deep space launch; Pioneer 0 exploded 77 seconds after liftoff.
Pioneer 1's goal was to collect data on ionizing radiation, cosmic rays, and magnetic fields around Earth before heading to the moon. A malfunction cut its mission short, but it did return to Earth with valuable information, including confirming the existence of the Van Allen radiation belt.