13 Mainstream Products Originally Invented for Space Travel

7. Space Pens (or Gravity Pens) Apollo 7 astronauts traded their trusty pencils for Fisher Space Pens developed for their 1968 mission. While gravity supplies regular pens with ink flow, requiring a level writing surface, space pen cartridges are pressurized to provide ink at all times. And they work well in extreme temperatures (and have changed the dynamics of graduation gifts!).