Mariner 2

Mariner 2 was a NASA spacecraft. It was the second spacecraft in the Mariner program. Mariner 2 was the first successful mission from Earth to another planet.
Mission.
Mariner 2 was launched on August 27, 1962 aboard an Atlas-Agena B rocket at Cape Canaveral Air Force Station. The aim of the Mariner 2 mission was to fly-by the planet Venus and return information on the planet's atmosphere, magnetic field, charged particle environment, and mass. Mariner 2 was at its closest to Venus, at a distance of 34,773 km, on December 14, 1962. Orbital perihelion was on December 27, 105,464,560 km away. The last radio signal from Mariner 2 was received on January 3, 1963. Mariner 2 is still orbiting around the Sun today.
Design.
The spacecraft's design was exactly the same as that of Mariner 1. Mariner 1 was the first spacecraft in the Mariner program, but it had to be destroyed shortly after launch because its trajectory was wrong.
Discoveries.
The spacecraft found out that the surface temperature on Venus was at least 425 °C (797 °F), on both the day and night sides. It discovered that Venus rotates in the opposite direction from most planets in the Solar System. The spacecraft also found that the atmosphere of Venus is mostly of carbon dioxide and that there is a very high pressure at the planet's surface. Continuous cloud cover was detected but no magnetic field was, however. It also found that solar wind is continuous and that the density of cosmic dust between planets is much lower than it is near Earth.