The first successful interplanetary spacecraft probed the environment of Venus, Earth’s closest neighbor. Mariner 2, working flawlessly, swept by the hot and cloudy planet at a closest approach of 34,834 kilometers (21,645 miles) on December 14, 1962.

The journey began with lift-off on August 27 from Cape Canaveral atop an Atlas Agena-B launch vehicle. During the 109-day trip to the planet, Mariner’s on-board instruments sampled the environment of interplanetary space and telemetered information to Earth stations. Ground-based measurements of the Venerian surface temperature were confirmed by the probe to be around 425° C (800° F).

Mariner 2 detected no measurable magnetic field or radiation belts, indicating that Venus may have a very different history than has Earth.

Mariner 2 passed out of tracking range on January 4, 1963, when the spacecraft was about 87 million kilometers (54 million miles) from Earth. The probe is presently in orbit around the Sun.

The back-up craft on display would have been launched toward Venus if Mariner 2 had failed to reach the planet.

Prime contractor for Mariner 2 was the Jet Propulsion Laboratory, California Institute of Technology.

Mariner 2 is from the National Aeronautics and Space Administration.