In the early 1950s, an American, Paul Fisher, noticed that although there were many types of ballpoint pen available on the market, each pen required a different type of cartridge. In 1953, Fisher invented the universal refill which could be used in most pens. It sold well, as stationers were able to reduce their stocks of assorted refills.

Research and Development

In the mid-'50s Fisher established the Fisher Space Pen Company, based in California, USA. Currently, its headquarters are in Boulder City, Nevada. In July 1958, using practical experiments, Fisher undertook the development of the ballpoint pen. Ballpoints rely on gravity to feed the ink and have an opening in the top of the ink cartridge to allow air to replace the ink as it is used. Fisher developed the pen so that there was no hole in it. This eliminated the problems of wasted and evaporated ink. In addition, it prevented ink leaking from the rear of the ink reservoir.

Initially, the cartridge was pressurised with nitrogen to a level of 50 pounds per square inch (about 350kPa). This means that gravity is not needed for the pen to work, as ink is continuously fed to the tungsten carbide ball. The original design was manufactured in aluminium.

A further development was to use thixotropic ink. The ink has a consistency similar to thick, rubber cement. It is held in a semi-solid gelatinous state, until the shearing action of the rolling ball in its socket liquefies the ink. Thus, the ink only flows when needed, allowing the pen to write smoothly and dependably on most surfaces.

Performance

Results from tests indicated that the shelf-life of a space pen is an estimated 100 years. This compares very favourably with standard ballpoint pens, which have an estimated life span of two years.

The pen can perform in a variety of temperatures from -25°C to 120°C. It can write on wet surfaces, so it can be used in the rain, snow and even underwater. It can write on coated plastic, carbonless paper and through images of fingerprints. It is not affected by dirt or grease. It can write on latex gloves, without the gloves tearing. It can write on wet timber, sheet metal duct work and camera film. Users can write at any angle, even upside down.

The Space Missions

Fisher soon realised that a major advantage to the design was that standard ballpoint pens are unable to perform in zero gravity conditions and patented his design as the Anti-gravity Pen in 1965.

Having completed two years of testing, NASA selected the pen for use on all the Apollo missions, as it proved extremely accurate. Beginning with the Apollo 7 mission in 1968, astronauts used the Fisher AG-7 Space Pen and cartridge. Currently, the pen is used for all manned space flights, both American and Russian.

Due to its unique design and reputation for writing in extreme conditions, the pen has been chosen for use by the United States Air Force, undersea explorers, ski teams and mountain climbers. In 1997, the pen was used during the Everest North Face Ski Expedition. In 1998, it was used on the Russian Space Station Mir. The pen was used to write the letters of a shopping TV channel, and became the first product sold in space.

The Modern Space Pen

Fisher's original pen, designed in 1948 was the No 400 Chrome Bullet Pen. Cited as an outstanding example of industrial art, it is exhibited in the New York Museum of Modern Art. It was designed to take standard refills but coupled with the new cartridge is still a one of the most popular of the Fisher pen designs.

Fisher developed the pen further, so that currently the pen is available in a range of styles, colours and materials. The pens can be purchased with a rubber lower barrel, which gives additional grip.

The cheapest space pen costs around $10. All Space pens are supplied in a gift box and each contains a black ink refill. The inks can be supplied in a range of colours including gold and silver. Customised pens can be engraved.

Speciality pens were designed. One design of pen includes the Triple Action Space Pen. It has the advantage of being able to use black ink, red ink or a 0.7mm mechanical pencil. All of these are contained in the one pen. The Alan Shepard Golf Space Pen features a unique telescopic pull action mechanism, which exposes the ink cartridge, forming the design into a full-length writing instrument. This design can be fitted into the top pocket of a shirt, and has the advantage in that the user does not have to remove a cap. In 1985, the range developed to include the Stowaway Pen. It is manufactured in gold, taken from the treasure recovered from the 1622 Spanish Galleon Nuestra Señora de Atocha.

Cons

The disadvantage to the design is that refill ink cartridges are needed, and can only be supplied through the Fisher organisation, which is ironic, given Fisher's initial concept.