Luna 1 (E-1 series), also known as Mechta (Мечта, lit.: Dream) was the first spacecraft to reach the vicinity of the Moon and the first of the Luna programme of Soviet automatic interplanetary stations successfully launched in the direction of the Moon.
While traveling through the outer Van Allen radiation belt, the spacecraft's scintillator made observations indicating that there exist a small number of high energy particles in the outer belt. The measurements obtained during this mission provided new data on the Earth's radiation belt and outer space. It was discovered that the Moon had 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 kilometres distance.
A malfunction in the ground-based control system caused an error in the rocket's burntime, and the spacecraft missed the target and flew by the Moon. Approaching it at 5,900 km at the closest point, Luna 1 has become the first object launched by mankind to reach heliocentric orbit. It was then dubbed a "new planet" and renamed Mechta. Its orbit lies between those of Earth and Mars. The name "Luna-1" was applied retroactively years later. Luna-1 was originally referred to as the "First Cosmic Rocket", in reference to its achievement of escape velocity.
It was intended that after a completion of its scientific mission of in-flight measurements, Luna-1 would crash into the Moon delivering two metallic pennants with the Soviet coat of arms that were included into its package.
Luna 1 became the first ever man-made object to reach the escape velocity of the Earth (what is also known as the second cosmic velocity), when it separated from its 1472 kg third stage. The third stage, 5.2 m long and 2.4 m in diameter, traveled along with Luna 1. On 3 January, 3:56:20 Moscow Time, at a distance of 119,500 km from Earth, a large (1 kg) cloud of sodium gas was released by the spacecraft, thus making this probe also the first artificial comet. This glowing orange trail of gas, visible over the Indian Ocean with the brightness of a sixth-magnitude star for a few minutes, was photographed by Mstislav Gnevyshev at the Mountain Station of the Main Astronomical Observatory of the Academy of Sciences of the USSR near Kislovodsk. It served as an experiment on the behavior of gas in outer space. Luna 1 passed within 5995 km of the Moon's surface on 4 January after 34 hours of flight. It went into orbit around the Sun, between the orbits of Earth and Mars.