Because it is our closest planetary neighbor and because it seemed so earth-like in proportion, Mars had always held a special fascination for astronomers. Early on, they had determined the planet had a rotation cycle similar to that of Earth, and that its poles were also likely ice-covered. By the early 1900s, there was even wide speculation the planet could have intelligent life on it. After the moon was thoroughly explored and landed on, Mars was due up next.

On this day, November 14, in 1971, the Mariner 9 spacecraft, launched six and a half months earlier, went into orbit around Mars, the first spacecraft to orbit another planet.

The notion of Mars harboring intelligent life was borne out of a misinterpretation of Giovanni Schiaparelli’s “canali” — he meant lines, but it was more often translated as “canals,” implying a builder, and American Percival Lowell’s fantastical theories. With a collection of sensors, cameras and radiometers, the Mariner 9 was well equipped to find that life, if it existed. But it had to wait a month to get any kind of surface reading, as a gigantic dust storm on the surface obscured it from view. Perhaps it was just a cover until the Martians could hide themselves.