Lunokhod 1 — first wheeled rover to operate on another body

On 17 November 1970, ramps unfolded from the Luna 17 lander in Mare Imbrium, the Sea of Rains, and an eight-wheeled machine rolled down onto the lunar dust. It was Lunokhod 1, the first wheeled vehicle ever to move across the surface of another world, and the strangest spacecraft the Soviet Union had yet flown: a 756-kilogram tub-shaped carriage with a hinged convex lid, television eyes, ramps facing both directions in case boulders blocked one exit, and a crew left behind on Earth.

That crew, five men at a time working in shifts at a Soviet deep-space control center, drove by television, with every command crawling across the void and every picture arriving late. By lunar day, solar cells on the open lid charged the batteries; at sunset the lid closed and a polonium-210 radioisotope heater kept the electronics alive through two-week nights of minus 150 degrees Celsius. Designed to last three lunar days, the rover kept answering Earth's calls for eleven.

By the time operations ceased in the autumn of 1971, Lunokhod 1 had driven 10.54 kilometres, returned more than 20,000 television images and 206 high-resolution panoramas, run 25 chemical analyses of the soil and tested its bearing strength at over 500 points. Then it vanished from precise human knowledge for four decades, until NASA's Lunar Reconnaissance Orbiter photographed it in March 2010. Weeks later, physicists at Apache Point Observatory fired a laser at the new coordinates, and the rover's French-built retroreflector flashed back, startlingly bright, ready to do science again.