Forty-five years ago today — June 14, 1967 — Mariner 5 launched from Cape Canaveral atop an Atlas Agena rocket.
(Mariner 5. NASA image.)
Mariner 5 was originally built as a backup for the Mariner 4 mission to Mars, but was refurbished and sent to Venus instead.
Mariner 5 flew by Venus on October 19, 1967, passing about 4,000 km from the yellow planet. Instruments on the spacecraft “measured both interplanetary and Venusian magnetic fields, charged particles, and plasmas, as well as the radio refractivity and UV emissions of the Venusian atmosphere.”by