Luna 1

Luna 1 (Russian: Lunik I | Space Rocket I) was the first spacecraft to reach the Moon and the first of the Luna program of Soviet automatic interplanetary stations successfully launched in the direction of the Moon. While passing through the outer Van Allen radiation belt, the spacecraft's scintillator made measurements indicating that there are very few high energy particles in the outer belt.

The spacecraft was sphere-shaped. Five antennae extended from one hemisphere. Instrument ports also protruded from the surface of the sphere. There were no propulsion systems on the Luna 1 spacecraft itself. Because of its high velocity and its announced package of various metallic emblems with the Soviet coat of arms, it was concluded that Luna 1 was intended to impact the Moon.

On January 2 1959, after reaching escape velocity, Luna 1 separated from its 1472 kg third stage. The third stage, 5.2 m long and 2.4 m in diameter, travelled along with Lunik I. On 3 January, at a distance of 113,000 km from Earth, a large (1 kg) cloud of sodium gas was released by the spacecraft. This glowing orange trail of gas, visible over the Indian Ocean with the brightness of a sixth-magnitude star, allowed astronomers to track the spacecraft. It also served as an experiment on the behavior of gas in outer space. Lunik I 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.

The spacecraft contained radio equipment, a tracking transmitter, and telemetering system, five different sets of scientific devices for studying interplanetary space, including a magnetometer, geiger counter, scintillation counter, and micrometeorite detector, and other equipment. The measurements obtained during this mission provided new data on the Earth's radiation belt and outer space, including the discovery that the Moon had no magnetic field and that a solar wind, a strong flow of ionized plasma emmanating from the Sun, streamed through interplanetary space.