When
NASA first started sending up astronauts, they quickly discovered that ballpoint pens would not work in
zero gravity. To
combat the problem, NASA scientists spent a decade and $12 billion to develop a pen that writes in zero gravity, upside down, underwater, on almost any surface including glass and at temperatures ranging from below freezing to 300 C. The Russians used a pencil.
Source:
http://ilucky.bokee.com