At the height of the space race in the 1960s, NASA scientists were perplexed by a problem their astronauts faced in the recording of data and experience while in orbit. The problem was that they were unable to write anything down, because they could not get a pen to work at zero gravity. To crack this difficult nut, NASA embarked on an expensive research and development program. Some time and a million dollars later (a lot of money at that time), they proudly presented their "astronaut pen", which immediately went into service. Happy astronauts were able to record data to their hearts' content. This astronaut pen also achieved some success as a novelty item, sold at great expense to earthlings as a genuine NASA souvenir.
Meanwhile, the Soviet space agency had solved its own pens-not-working-at-zero-gravity problem. They used pencils.
Taken from Truth, Lies & Advertising by Jon Steel