In the 1960s, NASA wanted an avoid using pencils because the lead could easily break off and float away.
If you have seen the Bollywood movie '3 Idiots' starring Aamir Khan, R Madhavan and Sharman Joshi, you might also remember a scene where the dean of the college played by Boman Irani, where they studied, asked why is a Space Pen used instead of the cheaper pencils while going to space?
Well, that's an oft asked question and the National Aeronautics and Space Administration (NASA) certainly has an answer for the same.
In the 1960s, NASA wanted an avoid using pencils because the lead could easily break off and float away, creating a hazard to astronauts and sensitive electronics on the spacecraft. Apart from this, pencils are flammable, and NASA wanted to avoid anything flammable aboard a spacecraft. Cosmonauts also have been using Space Pens since 1969.
However, regular pens that work on Earth do not work in space because they rely on gravity for the flow of ink to the nib.
Then Paul C. Fisher of the Fisher Pen Co. came to NASA's rescue and designed a ballpoint pen that could work in space. His company invested one million dollars to fund, design and patent the pen, which could operate in temperatures ranging from -50 F to +400 F.
After rigorous testing, NASA gave the Space Pen to astronauts for use. The pens have been used on every crewed NASA mission since Apollo 7 – dozens are currently aboard the International Space Station.