Engineered by Paul Fisher in 1965, the Space Pen's sealed, pressurized cartridge allowed ink to flow to its roller ball at any angle or in zero gravity. Astronauts carried Fisher's AG-7 Space Pen with them starting with Apollo 7 in 1968. In 1969, the AG-7 was on board when Buzz Aldrin used a pen to activate a broken circuit breaker that helped control the main engines for lifting off the moon's surface. American consumers in the grip of space fever could buy the pen that wrote upside down for $3.95 (about $22.00 today), an excellent deal given its advertised 100-year shelf life. Today, that promise is gone and the pen costs $30.00, perhaps a small price for its place in history. Too bad Buzz Aldrin later described the heroic pen as "felt-tipped."