A review of the contamination physics and of the most widespread engineering approaches to contamination assessment was carried out. The two main approaches are the physical and the empirical one. The main questions still open to validate the physical approach to outgassing and deposit physics were then studied. Among others, special attention was paid to the important point of a realistic separation of chemical species, probably a prerequisite for a physical modeling. Several original results were obtained. Some lead to a quite clear conclusion, like the preeminence of the limitation by desorption over the limitation by diffusion for outgassing. This observed trend needs yet to be validated on other materials. Other major results are progress on the validation of the physical approach and on the ambitious species separation program. Nomenclature D = Fick's law diffusion coefficient, cm 2 :s 1 E A = activation energy, J:K:mol 1 f = contaminant flux density, g:cm 2 :s 1 k = outgassing kinetic constant, s 1 L = effective diffusion length of the sample, m M = contaminant molar mass, g=mol m, m evap = deposited, evaporated or outgassed surfacic mass, g:cm 2 m 0 = contaminant monolayer mass, g:cm 2 n vol = contaminant volume density, g:cm 3 n surf = contaminant surface density, g:cm 2 P S = saturation vapor pressure, mbar R = gas constant, 8:314 J:K:mol 1 T = temperature, K t = time, s W = relative contaminant mass, % = outgassing or deposit evaporation characteristic time, s

This review focuses on advanced materials already used and suitable for application in (future) lunar extravehicular activity space suits. A historical and current literature/market survey is presented. Different functional layers of an astronaut garment are defined with emphasis on the external layers subjected to abrasive action of lunar regolith and degradation via exposure to space radiation/vacuum environment. Requirements are defined that would need to be fulfilled by these layers and suitable materials candidates are reviewed based on their key properties, including mechanical durability. Smart materials, combining additional functionalities, such as garment health monitoring, are also considered. The lead topic is the subject of an ongoing ESA‐funded research activity.

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In this research the ageing of a silicone adhesive in a simulated space environment is monitored through an embedded three parameter tilted Fibre Bragg Grating (TFBG) sensor. Here, the silicone is used as an adhesive between two thin cover glasses, and the space environmental ageing is simulated by thermal cycles in high vacuum conditions (better than 10-5 mbar). These operational conditions can induce variations in the silicone adhesive with respect to its original properties such as dimensional stability, chemical composition, generated contaminants, discoloration and, mechanical or optical degradation. Therefore, surrounded by the adhesive, in the centre of the cover glass sandwich, a weakly tilted FBG sensor was placed to obtain information from its spectra on the state of the polymer during the test. Specifically, the temperature, strain and refractive index (RI) of the silicone can be, simultaneously and separately, measured from the spectrum of a single TFBG from selected resonance peaks. These parameters can be used to evaluate the “health” state of the silicone during the vacuum thermal cycles. The simultaneous TFBG thermomechanical measurements gave a solution to the non-localized measuring issues when using classical fibre optic or electrical strain-gauges and a thermocouple (TC) to compensate the temperature and to better understand the material behaviour. The trends of the measured parameters are reported during the entire testing time, and at the end of the test, the optical fibre sensor measured a negative strain of ~100 με and a positive RI variation of ~0.002.