On the microstructure and structure of the polyimide film surface and condensed substances after long-term exposure on the space station

Complex research of polyimide film microstructure and chemical composition has been conducted by scanning electron microscopy, electronic probe microanalysis and infrared spectroscopy. Changes in layers’ surface and in substances condensed on films were studied after long-term exposure (1218 days) on Mir space station. It is shown that during space exposure microstructure and chemical composition of the first layer suffer changes, but other layers of the package located below don’t reveal similar transformations. New phase formations of different shape and size with film and needle structure varying by its chemical composition have been found on an open surface of the first polyimide film layer. It has been established that the condensed substances consist of silicon, iron, copper, zinc, chlorine, potassium and calcium compounds, which are probably deposited from the outer atmosphere of the orbital station.