On the Microstructure and Chemical Composition of the Polyimide Film Surface and Condensed Substances after Long-Term Exposure at the Mir Space Station

Using scanning electron microscopy, electron probe microanalysis, and infrared spectroscopy, we comprehensively studied changes in the microstructure and chemical composition of the surface layers of the PM-1E polyimide film, as well as the substances condensed on it, which for a long time (1218 days) was exposed at the Mir orbital space station. It was shown that, during the exposure in space, the microstructure and chemical composition of the film changes only in the first layer of the packet and that no such transformations are observed in the layers located below. On the open surface of the first layer of the polyimide film, new phase formations of various shapes and sizes with both film and needle-like structures differing in chemical composition were discovered. It was found that the condensed matter formed consists of compounds involving silicon, iron, copper, zinc, chlorine, potassium, and calcium, which are likely to precipitate from the own external atmosphere of the orbital station.