Luna 3

The Moon keeps one face turned forever away from Earth. Every human who had ever lived, every astronomer with every telescope, had seen only the same half. On 7 October 1959, a Soviet probe swung beyond the Moon, looked back at the hidden hemisphere lit by the Sun, and at 03:30 Universal Time began taking pictures. Over the next forty minutes, from roughly 63,500 kilometres away, Luna 3 exposed 29 frames of film across terrain no eye had ever seen.

What followed was one of the most audacious engineering feats of the decade. Luna 3 carried an automated darkroom: the 35-millimetre film was developed, fixed, and dried on board, then scanned line by line with a moving spot of light and radioed home like a fax sent across hundreds of thousands of kilometres. The probe used the Moon's own gravity to bend its trajectory back toward Earth for transmission, the first gravity assist ever flown. According to accounts from Soviet engineers, the radiation-resistant film itself had been salvaged from American Genetrix spy balloons downed over Soviet territory.

The pictures were grainy, noisy, almost abstract. They were also revolutionary. About seventeen usable frames reached Earth, covering some seventy percent of the far side, and they showed a world startlingly unlike the familiar face: a bright, battered highland landscape almost devoid of the dark lava seas that pattern the near side. Soviet scientists claimed the discoverer's naming rights, charting the Sea of Moscow and the dark-floored crater Tsiolkovsky. Launched on 4 October 1959, two years to the day after Sputnik 1, Luna 3 turned the Moon from a flat icon into a three-dimensional world.