At the height of the Space Race both Soviet and American astronauts faced an unforeseen challenge: taking notes when the lack of gravity rendered normal pens inoperable. The Americans reputedly "spent millions" on an advanced pressurised space pen while the Soviets -- they simply brought pencils.
While this anecdote is really designed to illustrate the technical mindset differences between the US And USSR space programs it is based on a true story. The space pen NASA employed during the Apollo program wasn't designed by the government agency but rather the Fisher Space Pen Co. Paul Fisher, the company's founder and inventor of the universal ink refill cartridge, had reportedly sunk more than a million dollars and multiple years developing the "anti-gravity" AG7 pen when he submitted his design for testing in 1966. Two years later, Apollo 7 astronauts carried them into orbit.
The AG7 utilises a sealed cartridge filled with gelled ink that liquefies only when exposed to pressure, conveniently provided by another cartridge filled with inert nitrogen gas. The tungsten carbide ballpoint tip prevents interaction between the ink and the surrounding environment, meaning the pen can write upside-down, underwater, in temperatures ranging from -34C to 120C, and of course, in the weightlessness of space.
The Fisher Space Pen is still being made today, you can pick one up for $US50. As for the Russians' Space Pencils, turns out graphite and wood shavings make for an explosive mixture in the cramped, oxygen-rich interiors of orbiters -- as the Apollo 1 fire illustrated -- and have since been replaced with, what else, the Fisher Space Pen.
Check out the full story of America's fabled Anti-Gravity Pen over at the Smithsonian.
Pictures: Fisher Space Pens; USPTO