Surveyor 1 descended onto the Moon's Ocean of Storms using retrorockets and a radar altimeter, achieving a gentle touchdown on its first attempt, an unexpected success for a program still working out the kinks of automated landing. Within hours it beamed back the first pictures ever transmitted from the lunar surface by an American craft, paving the way for the crewed Apollo landings three years later.
NASA engineers had budgeted for failure. The Surveyor program was notoriously complex, requiring a spacecraft to detect its own altitude and velocity, fire retrorockets at precisely the right moment, and shed its remaining fall in a survivable crash-landing onto an alien surface no human had ever touched, all without any real-time human control given the roughly 1.3-second radio delay each way.
On the night of June 1 into June 2, 1966, Surveyor 1 executed its automated descent sequence over the Ocean of Storms, a dark lunar mare chosen partly because Apollo planners wanted to know whether its surface could support a landing craft's weight. To the surprise and relief of the JPL team, who had expected to spend the mission diagnosing what went wrong, the spacecraft settled onto the dust with only a gentle bounce.
Within hours it transmitted the first close-up photographs of the lunar surface taken by an American craft, showing a firm, rock-strewn plain rather than the deep dust some scientists had feared would swallow any lander. The pictures were front-page news around the world and gave NASA crucial reassurance, just three years before Apollo 11, that a lunar module's footpads would not sink helplessly into the ground.