Crayons and pencils work by scraping their material onto the writing surface. This process often causes bits and particles of the writing material to flake off from the writing implement and the paper. read more
There was an urban legend that the astronaut pen cost millions, but the reality is NASA purchased 34 pens from Houston's Tycam Engineering at about $129 per pen. Expensive, but hardly a large part of the space program budget. read more
Pencils cause a problem when broken and when sharpening as the create dust that can fly around the spacecraft. You can solve these problems but all cost time and add weight to the flight. read more
NASA had to really work until they invented the famous “Fisher Space pen” specifically for the purpose. But this stuff is quite expensive. For general usage, astronauts have resorted to the use of markers and to a lesser extent, mechanical pencils. read more