Luna 1

Luna 1, also known as Mechta (Russian: Мечта, lit.: Dream),E-1 No.4 and First Cosmic Ship, was the first spacecraft to reach the vicinity of the Earth's Moon, and the first spacecraft to be placed in heliocentric orbit. Intended as an impactor, Luna 1 was launched as part of the Luna programme in 1959, however due to an incorrectly timed upper stage burn during its launch, it missed the Moon; in the process becoming the first spacecraft to leave geocentric orbit.

While traveling through the outer Van Allen radiation belt, the spacecraft's scintillator made observations indicating that a small number of high energy particles exist in the outer belt. The measurements obtained during this mission provided new data on the Earth's radiation belt and outer space. The Moon was found to have no detectable magnetic field. The first ever direct observations and measurements of the solar wind, a strong flow of ionized plasma emanating from the Sun and streaming through interplanetary space, were performed. That ionized plasma concentration was measured to be some 700 particles per cm³ at altitudes 20-25 thousand km and 300 to 400 particles per cm³ at altitudes 100-150 thousand km. The spacecraft also marked the first instance of radio communication at the half-million-kilometer distance.