The Space Pen, generally referring to the ones marketed by Fisher Space Pen Co., is a particular type of pen. It uses pressurized ink cartridges to allow for features in addition to those offered by a standard ballpoint pen.

Detailed information

• The ball is made from ultra-hard tungsten carbide
• A sliding float separates the ink from the pressurised gas
• The thixotropic ink in the hermetically sealed and presurised reservoir is claimed to write for three times longer
• The gas is pressurised at nearly 50 pounds per square inch (340 kPa)
• Operating temperatures range from -50 to 250 degrees Fahrenheit (-45 to 120 degrees Celsius)
• The pen has an estimated shelf life of 100 years
• There are two styles of the pen, the 'Astronaut', a long thin version shaped like a common ballpoint and a 'Bullet' pen which is considerably smaller and is unique among pen designs

Special abilities

• Can write at any angle, for instance while being held upside down.
• Ink is rarely leaked, creating an advertised shelf life of up to a century.
• Can write on 'carbonless' surfaces, such as plastic.
• Is not inhibited by extreme temperatures.
• Will operate without the aid of gravity (hence the term 'space' pen, referring to its use by Astronauts in zero gravity)
• Can write underwater.

Cultural appearances

There exists a common rumor claiming that NASA spent millions of dollars developing the Space Pen, with the humorous note that the Russian space agency opted to simply use pencils. This has been debunked several times, for instance by Snopes. A bullet style Space pen is on permanent display at the New York Museum of Modern Art (MOMA). The Space Pen was featured on an episode of the American television show Seinfeld.

Criticism

The 'visco-elastic' ink used by Space Pens is said by many detractors to be 'sticky'. Furthermore, the reasonable applications of Space Pens are, for most, too few to surmount their prohibitive cost (as opposed to the more popular ballpoint pen).