Monitoring troop movements could be made much easier with the introduction of a luminous chemical which works like a gigantic magic marker. German chemical company, Lanxess, have developed a product called Rapidogen, which is invisible to the naked eye, but glows under UV light. Changes to terrain the size of a postcard can be detected using a laser-based monitoring system from a distance of 100m, in a helicopter for example.

The new chemical could soon be available as a tool for security, Marina Murphy reports in Chemistry & Industry, the magazine of the SCI. It can be sprayed over airports, railways, supply pipelines and even nuclear power plants. The system has already been tested by the German military at Luneburg Heath.

The principle could also be used as a safety measure for the space shuttle, for example, as problems, such as missing tiles, can be checked quickly. The system may also have a role in detecting preparations for terrorist attacks, or to find evidence of sabotage on roads or railway lines.

The chemical, which is resistant to rain, can stick to a surface for up to three months. It is a photochemical indicator which is slowly broken down by sunlight, with a built in timer causing luminosity to decrease over time. A spokesperson from Lanxess said: "We have had a great deal of interest in our invention and we are currently holding a number of talks."