Pioneer 4

NASA’s Pioneer 4 space probe is launched toward the moon atop a Juno II booster. For the first time in the Pioneer program, the target is reached, with Pioneer 4 passing the moon at a distance of 37,000 miles. The television camera designed to activate just in time to catch the first glimpse of the lunar far side fails to deploy, thanks to a light sensor that isn’t tripped by the light reflected from the moon. Measurements of radiation near the moon are taken and transmitted back to Earth before Pioneer 4 slides into an orbit around the sun.