The space pen, or pressurized ballpoint pen, is a novel technology. Take Fisher Space Pen as an example. The pen core of the space pen is pressurized (~0.28MPa), and its ink is a special viscous ink (like viscous rubber glue). To turn the viscous ink into a liquid, the ball must rotate so that the ballpoint pen can write smoothly on most surfaces and even underwater. Ordinary ballpoint pens rely on gravity to supply ink, and there is an opening above the refill so that air can replace the used ink. The space pen has no small holes, thus avoiding the evaporation and waste of ink, and also avoiding ink leakage from behind the refill. In addition, the service life of a space pen can be as long as 100 years. In contrast, the average shelf life of a regular ballpoint pen is only two years.

Since the start of the "Space Race" in the 1960s, the space pen has been used by American astronauts in all manned space flights including the moon landing project. In addition, they are also used by many Russian astronauts during the Soyuz space flight and on the Mir space station.