Fisher Bullet Series Space Pens

The Fisher Space Pen was selected by NASA (after rigorous testing) for use on all manned space flights because it is the only type of pen that will write satisfactorily in the gravity-free void, freezing cold (-50F) and extreme heat (+250F) of Space. Nitrogen-powered, the ink in the replaceable Space Pen cartridge is positively fed to the tungsten carbide ball by gas at three to six times atmospheric pressure. Pressurization required the development of a new special viscoelastic (chewing gum-like) ink that is highly thixotropic, so that it will not ooze through Fisher's high precision, stainless steel point. The revolving ball liquefies the thixotropic ink, which allows the Space Pen to write smoothly and dependably on most surfaces, and even under water.