Editing Ballpoint pen (section)

== Use of ballpoint pens in space ==

It is generally believed that gravity is needed to coat the ball with ink. In fact most ballpoint pens on the Earth do not work when writing upside-down because the Earth's gravity pulls the ink inside the pen away from the tip of the pen. However, in the microgravity environment of space a regular ballpoint pen can still work, pointed in any direction,  because the capillary forces in the ink are stronger than non present gravitational forces.
The functionality of a regular ballpoint pen in space was confirmed by ESA astronaut Pedro Duque in 2003.<ref>{{Cite web |title=Pedro Duque's diary from space |url=https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/Cervantes_Mission/Pedro_Duque_s_diary_from_space |access-date=2023-09-28 |website=www.esa.int |language=en}}</ref>

Technology developed by Fisher pens in the United States resulted in the production of what came to be known as the "Fisher [[Space Pen]]". Space Pens combine a more viscous ink with a pressurized ink reservoir<ref name="How ballpoints work"/> that forces the ink toward the point. Unlike a standard ballpoint's ink container, the rear end of a Space Pen's pressurized reservoir is sealed, eliminating evaporation and leakage,<ref name="How ballpoints work"/> thus allowing the pen to write upside-down, in zero-gravity environments, and allegedly underwater.<ref>{{cite web|url=http://www.spacepen.com/about-us.aspx|title=Fisher Space Pen – About Us|access-date=5 November 2011|archive-date=28 April 2015|archive-url=https://web.archive.org/web/20150428143620/http://www.spacepen.com/about-us.aspx|url-status=live}}</ref> Astronauts have made use of these pens in outer space.<ref name="How ballpoints work"/>