Mariner 2 was the first successful spacecraft in the NASA Mariner program, which began by sending spacecraft to Venus. The Mariner 1 and 2 spacecraft were simplified versions of the Block I spacecraft of the Ranger program.

The Mariner probe consists of a 100 cm diameter hexagonal bus, to which solar panels, instrument booms, and antennae were attached. The scientific instruments onboard the Mariner spacecraft were two radiometers (microwave and infrared) mounted on a tilting platform, a micrometeorite sensor, a solar plasma sensor, a charged particle sensor, and a magnetomoeter. These instruments were designed to measure the temperature distribution on the surface of Venus, as well as making basic measurements of Venus's atmopshere. Due the the thick cloud cover, no cameras were included in the Mariner units.

The Atlas-Agena rocket carrying Mariner 1 veered off-course during its launch on July 22, 1962, and the spacecraft was destroyed. A month later, the identical Mariner 2 spacecraft was launched successfully on August 27, 1962, sending it on a 3½-month flight to Venus. On the way it measured for the first time the solar wind, a constant stream of charged particles flowing outwards from the Sun. It also measured interplanetary dust, which turned out to be more scarce than predicted. In addition, Mariner 2 detected high-energy charged particles coming from the Sun, including several brief solar flares, as well as cosmic rays from outside the Solar system. As it flew by Venus on December 14, 1962, Mariner 2 scanned the planet with its pair of radiometers, revealing that Venus has cool clouds and an extremely hot surface.

External links

NASA-Jet Propulsion Labratory Guide to Mariner 2