In the 1960s, the story goes, NASA realized that astronauts would need a special pen for recording data, instrument readings etc. when in space. This pen would have to be capable of writing upside-down, in zero gravity, and in extremely high and low temperatures.

NASA enlisted some of the finest minds in the country and set them to work. After much trial and error, years of work, and the expenditure of 1.5 million dollars, they finally succeeded in developing a space pen. And the Russians? The Russians used pencils.

(From BBC History Magazine)