Sileye on mir : First active detector for the study of light flashes in space

Since the Apollo-1 1 flight it is known that humans in space may experience light flashes, which do not have some direct light as their source. Several studies in the 1970-ies indicate that cosmic particles is the source of the phenomenon, but there are still no conclusive data on which kind of particles and what is the exact effect in the eye giving rise to the light flash experience. The SilEye project investigates these questions, using as its main tool a silicon detector which is mounted as a telescope in front of the eye of an astronaut. The apparatus can in real time detect particles which traverse the eye. A pilot detector was sent to Mir in October 1995 and the first data have been analyzed. Protons and ions are seen. At least one light flash event is correlated with a determined particle. Indirectly the indications are that it is rather heavy ions than protons that is the main cause of the light flashes.