As plans were getting under way to explore the Moon with the Rangers and Surveyors, JPL and NASA also turned their attention to the rest of the solar system. The Mariner series of missions were designed to be the first U.S. spacecraft to other planets, specifically Venus and Mars. Mariner 1 and 2 were nearly identical spacecraft developed to fly by Venus. The rocket carrying Mariner 1 went off-course during launch on July 22, 1962, and was blown up by a range safety officer about 5 minutes into flight.
A month later, Mariner 2 was launched successfully on August 27, 1962, sending it on a 3-1/2-month flight to Venus. On the way it measured for the first time the solar wind, a constant stream of charged particles flowing outward 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 infrared and microwave radiometers, revealing that Venus has cool clouds and an extremely hot surface. (Because the bright, opaque clouds hide the planet's surface, Mariner 2 was not outfitted with a camera.)
Mariner 2's signal was tracked until January 3, 1963. The spacecraft remains in orbit around the Sun.
Mass: 203 kilograms (447 pounds)
Science instruments: Microwave radiometer, infrared radiometer, flux-gate magnetometer, ion chamber and Geiger-Mueller counters, cosmic dust detector, solar plasma detector
Mariner 1 launch: July 22, 1962
Mariner 2: August 27, 1962
Mariner 2 Venus flyby: December 14, 1962
