Luminous paint paint was used to illuminate Apollo Lunar Module electrical switch tips and painted on control panels of the Lunar Roving Vehicle. The latest generation of the radioluminescent materials is based on tritium, a radioactive isotope of hydrogen with half-life of 12.32 years that emits very low-energy beta radiation. The devices are similar to a fluorescent tube in construction, as they consist of a hermetically sealed (usually borosilicate-glass) tube, coated inside with a phosphor, and filled with tritium. They are known under many names – e.g. gaseous tritium light source (GTLS), traser, betalight. Tritium light sources are most often seen as
Tritium radioluminescence to phosphoresce. During manufacture, a length of borosilicate glass tube that has had the inside surface coated with a phosphor-containing material is filled with radioactive tritium. The tube is then sealed at the desired length using a carbon dioxide laser. Borosilicate is preferred for its strength and resistance to breakage. In the tube, the tritium gives off a steady stream of electrons due to beta decay. These particles excite the phosphor, causing it to emit a low, steady glow. Tritium is not the only material that can be used for self-powered lighting. Radium was used to make self-luminous paint from