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Results of simulation testsof the influence of the protective and functional coatings on the resistance of polymeric constructional spacecraft materials to the impact of atomic oxygen with fluences up to 3.5 × × 10 22 cm −2 are presented. It was demonstrated that oxygen plasma beams can be used in accelerated tests of carbon-based and polymeric material structures (with the exception of filled and fluorinated hydrocarbons) to evaluate their resistance to the atomic oxygen impact in low Earth orbit. For unprotected materials, a sharp fall of mechanical properties and a deterioration of optical characteristics were observed. The application of protective coatings is shown to reduce this degradation. Nomenclature dF = fluence increment dM = mass loss E = atomic oxygen translation energy f = normalized energy dependence K = Kapton ® index M = material index Y = erosion yield γ = protection efficiency

About 60 samples of various materials exposed to low Earth orbit (LEO) conditions for 997 days on board the orbital space station ‘Mir’ were investigated. The aim was to determine the properties of the contamination layers formed during LEO exposition. The following methods were used: optical and scanning electron microscopy, local x-ray microanalysis, secondary ion mass spectrometry in fast atom bombardment ionization mode, electron spectroscopy for chemical analysis, temperature programmed desorption mass spectrometry, x-ray phase analysis, spectral reflectance, solar absorbance and relative emittance measurements. Two effects were observed for all samples: the formation of contamination deposits and the erosion of the substrate–original surface. The relative contribution of both effects changes depending on the sample type and on exposure conditions. The deposit thickness varies on the sample surface over a very wide range (at least five decimal orders of magnitude), changing from values exceeding 100 μm to values of less than 2 nm (possibly these regions do not contain any deposit at all). The main element of contamination is silicon; the others are potassium and calcium. Evidence of a chemical reaction between the Teflon FEP substrate and the contamination was observed.

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This paper presents an overview of International Space Station (ISS) on-orbit environments exposure flight experiments. International teams are flying, or preparing to fly, externally mounted materials exposure trays and sensor packages. The samples in these trays are exposed to a combination of induced molecular contamination, ultraviolet radiation, atomic oxygen, ionizing radiation, micrometeoroids and orbital debris. Exposed materials samples are analyzed upon return. Typical analyses performed on these samples include optical property measurements, X-ray photo spectroscopy (XPS) depth profiles, scanning electron microscope (SEM) surface morphology and materials properties measurements. The objective of these studies is to characterize the long-term effects of the natural and induced environments on spacecraft materials. Ongoing flight experiments include the U.S. Materials International Space Station Experiment (MISSE) program, the Japanese Micro-Particles Capturer and Space Environment Exposure Device (SM/MPAC&SEED) experiment, the Russian SKK and Kromka experiments from RSC-Energia, and the Komplast flight experiment. Flight experiments being prepared for flight, or in development stage, include the Japanese Space Environment Data Acquisition Attached Payload (SEDA-AP), the Russian BKDO monitoring package from RSC-Energia, and the European Materials Exposure and Degradation Experiment (MEDET). Results from these ISS flight experiments will be crucial to extending the performance and life of long-duration space systems such as Space Station, Space Transportation System, and other missions for Moon and Mars exploration.