Legend has it that after years of research and millions of dollars, Americans developed the space pen capable of writing in all sorts of extreme circumstances including zero gravity.
Russians used pencils.
Truth is space pens have been on every manned space flight. That's pretty darn cool. We haven't tested every condition with these pens, but we have written underwater, in freezing weather and upside down. They make great gifts and are the best emergency pen to keep handy.