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As part of a large program conducted between years 2010 and 2018, a number of ion beam surface treatments and proprietary coatings formed on advanced space polymers by direct ion beam deposition were developed at Integrity Testing Laboratory (ITL) Inc, in Canada. This technology allowed producing surfaces with controlled surface resistivity in a wide range of charge dissipation values, with negligibly low additional RF losses and other important functional properties, that allowed using such treated materials and products in modern space antennae, solar arrays and other external applications on spacecrafts in GEO environment. This paper will present an overview of results achieved throughout the years on enhancement of radiation stability of space polymers that were ion beam treated and coated with special multifunctional thin coatings by direct ion beam deposition. The treated/coated subjects have been ground-based tested in a range of radiation conditions, simulating the GEO radiation environment, conducted in three world-recognized GEO simulation facilities.

A novel ion-beam surface treatment process with simultaneous surface renewal (IB/SSR) providing charge-dissipative properties to the treated surfaces was developed at ITL and successfully used for treatment of both sides of variously shaped and sized flat conductor cables (FCC) that are being used in various applications in aerospace, space and commercial programs. The results of surface resistivity (SR) measurements of the front side of FCC’s used as interconnects in solar panel arrays on satellites in Geostationary (GEO) orbit averaged around 10 MΩ/sq for short FCC units and around 8 MΩ/sq for long units. The SR values for back sides averaged around 18 MΩ/sq for both short and long FCCs. These values remained unchanged during ~ 1 month storage of the treated FCCs at lab conditions, and after a following 2-2.5 year’s storage. Extended long-term ground-based GEO environment simulation testing experiments (15 years space equivalent) that involved simultaneous exposure to all three GEO environmental factors, i.e. protons, electrons, and UV have been performed on two specially selected FCC sets. These sets included pristine and IB/SSR-treated FCCs, with both front and back FCC surfaces being exposed. It was demonstrated that the surface conductivity obtained on the insulating space polymer films is almost insensitive to space radiation during the 15 years in GEO. It was also shown that the long-term influence of GEO radiation on thermal optical characteristics of both FCCs sides does not significantly differ for pristine and ion-beam treated samples., Новий процес обробки поверхні іонно-променевою поверхнею з одночасним оновленням поверхні (IB / SSR), що забезпечує дисипативні властивості заряду оброблених поверхонь, був розроблений в ITL і успішно використаний для обробки обох сторін різної форми та розміру плоских провідних кабелів використовуються для різних застосувань в аерокосмічній, космічній та комерційній програмах. Результати вимірювань поверхневого опору (SR) на лицьовій стороні FCC, що використовуються як взаємозв'язки в масивах сонячних панелей на супутниках на геостаціонарній орбіті (GEO), складали в середньому близько 10 МОм / кв. Для коротких блоків FCC та близько 8 МОм / кв. Для довгих блоків. Значення SR для тильних сторін у середньому становили близько 18 МОм / кв. Для коротких і довгих FCC. Ці значення залишались незмінними протягом ~ 1 місяця зберігання оброблених FCC у лабораторних умовах та після наступного 2-2,5 року зберігання.Розширені довготермінові експерименти з моделювання навколишнього середовища GEO (15-річний космічний еквівалент), які передбачали одночасний вплив усіх трьох факторів середовища GEO, тобто протонів, електронів та УФ, були проведені на двох спеціально підібраних наборах FCC. Ці набори включали незаймані та оброблені IB / SSR FCC, причому як передня, так і задня поверхня FCC були виставлені. Було продемонстровано, що поверхнева провідність, отримана на ізолюючих космічних полімерних плівках, майже не чутлива до космічного випромінювання протягом 15 років у ГЕО. Було також показано, що довгостроковий вплив ГЕО-випромінювання на теплооптичні характеристики обох сторін ФКК суттєво не відрізняється для зразків, що обробляються первинними та обробленими іонним пучком., Новый процесс ионно-лучевой обработки поверхности с одновременным обновлением поверхности (IB / SSR), обеспечивающий рассеивающие заряд свойства обрабатываемых поверхностей, был разработан в ITL и успешно использован для обработки обеих сторон плоских проводников разной формы и размеров (FCC), которые используются в различных приложениях в аэрокосмических, космических и коммерческих программах. Результаты измерений удельного поверхностного сопротивления (SR) передней стороны панелей FCC, используемых в качестве межсоединений в массивах солнечных панелей на спутниках на геостационарной (GEO) орбите, составили в среднем около 10 МОм / кв. Для коротких блоков FCC и около 8 МОм / кв. Для длинных блоков. Значения SR для задней стороны в среднем составляют около 18 МОм / кв как для коротких, так и для длинных FCC. Эти значения оставались неизменными в течение ~ 1 месяца хранения обработанных FCC в лабораторных условиях и после следующих 2-2,5 лет хранения.На двух специально отобранных наборах FCC были проведены расширенные долгосрочные эксперименты по моделированию среды на ГСО (космический эквивалент 15 лет), которые включали одновременное воздействие всех трех факторов окружающей среды ГСО, то есть протонов, электронов и УФ-излучения. Эти наборы включали первичные и обработанные IB / SSR FCC, с открытыми как передняя, так и задняя поверхности FCC. Было продемонстрировано, что поверхностная проводимость, полученная на изоляционных космических полимерных пленках, практически нечувствительна к космическому излучению за 15 лет работы в GEO. Также было показано, что долговременное влияние излучения GEO на теплооптические характеристики обеих сторон ГЦК существенно не различается для исходных и обработанных ионным пучком образцов.

Процес модифікації поверхні текстуруванням був розроблений для лицьових поверхонь тефлоновим теплозахисних покриттів напиляних з тильного боку металізованим покриттям Silver-Inconel. Ці теплозахисні покриття приклеювалися на наружні стінки корпусів які містять фотокамери та світлове обладнання на Міжнародній космічній станції. Розроблена технологія, що включає процес текстурування поверхонь іонним пучком, який міняв морфологію поверхні з дзеркально-гладенькою до світло-розсіювання і молочно-білою, значно знизила дзеркальність терморегулювальних плівок, не надавши істотного впливу на їх термооптичні властивості. Космічна апаратура, покрита таким текстурированним тефлоном, піддавалася впливу факторів відкритого космосу в період з червня 2002 року по червень 2006 року і була повернута на Землю приблизно в листопаді 2006 року. Текстурований тефлон, що пробув у космосі 4 роки, продемонстрував стабільні робочі характеристики, зі значеннями коефіцієнта сонячної абсорбції (α) і коефіцієнта випромінювання (ε) і їх відносин α / ε які збереглися близькими до початкових значень, виміряних до польотів. A texturing surface modification process was developed for Silver- Inconel coated Teflon thermal protection coverings that were applied to a camera and light equipment on the International Space Station using an adhesive. The developed treatment that involves an ion-beam texturing process that changes the appearance of the surface in a controlled manner from a metallic-like and shiny to complete milky-white appearance reduced dramatically the specularity of Silver-Teflon thermal control films without significantly affecting their thermal optical properties. The space hardware covered with the textured back metallized Teflon was exposed to the open space environment between June 2002 and June 2006 and delivered back to earth around November 2006. Remarkable performance was demonstrated by the treated metallized Teflon with the solar absorptance and total emittance values and the α/ε ratio remaining very close to the original values as measured before the flights. Процесс модификации поверхности текстурированием был разработан для лицевых поверхностей тефлоновых теплозащитных покрытий напылённых с тыльной стороны металлизированным покрытием Silver-Inconel. Эти теплозащитные покрытия приклеивались на наружные стенки корпусов содержащих фотокамеры и световое оборудование на Международной космической станции. Разработанная технология, включающая процесс текстурирования поверхностей ионным пучком, который менял морфологию поверхности с зеркально-гладкой и блестящей до свето-рассеивающей и молочно-белой, значительно снизила зеркальность терморегулирующих пленок, не оказав существенного влияния на их термооптические свойства. Космическая аппаратура, покрытая таким текстурированным тефлоном, подвергалась воздействию факторам открытого космоса в период с июня 2002 года по июнь 2006 года и была возвращена на Землю примерно в ноябре 2006 года. Текстурированный тефлон, пробывший в космосе 4 года, продемонстрировал стабильные рабочие характеристики, со значениями коэффициентов солнечной абсорбции ( α) и коэффициента излучения ( ε) и их отношения α/ε сохранившимися близкими к исходным значениям, измеренным до полетов.

Summary The ASTM Standard Test Method E2584 ‘Standard Practice for Thermal Conductivity of Materials Using a Thermal Capacitance (Slug) Calorimeter’ was developed by National Institute of Standards and Technology to measure thermal conductivity of fire-resistive and reactive materials during monotonic heating and cooling. The heating regime adopted in ASTM E2584 is very reasonable because change of materials' composition and structure during a fire can depend on kinetic factors and thermal story of the materials. The main problem in experimental measurements of thermophysical properties is the impossibility of using standard steady-state methods during time-dependent processes in materials accompanied by latent heat effect. Using standard transient methods, such as hot wire or laser flash methods, is also incorrect, because the transient measurement heat process can be started only after steady-state temperature field is established in the sample, that is, at the time when the involved physical or chemical processes could be finished. The objectives of this paper are to review and to analyze scientific problems to be taken into account in the revised version of ASTM E2584 Standard. Examples of experimental results are presented for measurement of thermophysical properties during chemical and physical processes in solid materials, powders, metals, and ceramic materials; building materials during fire; and so on. Copyright © 2016 John Wiley & Sons, Ltd.

The goals of the 10th International Space Conference on "Protection of Materials and Structures from Space Environment" ICPMSE-10J, since its inception in 1992, have been to facilitate exchanges between members of the various engineering and science disciplines involved in the development of space materials, including aspects of LEO, GEO and Deep Space environments, ground-based qualification, and in-flight experiments and lessons learned from operational vehicles that are closely interrelated to disciplines of the atmospheric sciences, solar-terrestrial interactions and space life sciences. The knowledge of environmental conditions on and around the Moon, Mars, Venus and the low Earth orbit as well as other possible candidates for landing such as asteroids have become an important issue, and protecting both hardware and human life from the effects of space environments has taken on a new meaning in light of the increased interest in space travel and colonization of other planets. And while many material experiments have been carried out on the ground and in open space in the last 50 years (LDEF, MEEP, SARE, MISSE, AOP, DSPSE, ESEM, EURECA, HST, MDIM, MIS, MPID, MPAC and SEED), many questions regarding the environmental impact of space on materials remain either poorly understood or unanswered. The coming generations of scientists will have to continue this work and tackle new challenges, continuing to build the level of confidence humans will need to continue the colonization of space. It is hoped that the proceedings of the ICPMSE-10J presented in this book will constitute a small contribution to doing so.

Responding to the need for dynamic outgassing testing at high temperature, ITL Inc. has developed and built an Outgassing Test Facility that accommodates the set-ups for measuring the outgassing of materials according to the ASTM E1559 test method. This paper describes the design of the outgassing system, operation of its devices and components, and presents the test results obtained on several advanced conductive and non-conductive space thermal control paints and silicones by MAP Space Corporation (France).

Alumina–aluminum MMC coatings were deposited by cold gas dynamic spraying onto aluminum alloy (Al 7570) substrates. The microstructure, phase composition, thermal conductivity, microhardness, and thermal optical properties (solar absorptance αs and thermal emittance e) of four types of coating were determined on as-sprayed samples and samples subjected to atomic oxygen (AO) plasma, intended to simulate conditions in outer space environment. In addition, time-of-flight (ToF) secondary ion mass spectrometry (SIMS) was applied to determine the responses of the coatings to oxidation by AO plasma. The results indicate that the very low thermal conductivity (λ), low solar absorptance (αs), comparatively high infrared emittance (e) and oxidation stability of the investigated coatings may provide adequate protection as environmental control coatings of space-bound materials against deleterious effects of space environment within the Low Earth Orbit (LEO) and beyond.

A novel method has been developed to measure the apparent thermal conductivity of thin coatings based on measuring the heat flux through the coatings as well as the external heat transfer coefficient of an uncoated sample using a modified slug calorimeter configuration. The method was tested on cold gas dynamically sprayed alumina-reinforced aluminum coatings deposited on Al 7075 alloy substrates, and verified by a standard steady-state method. The very low apparent thermal conductivities measured between − 150 °C and + 200 °C have been attributed to the presence of numerous splat boundaries, pores and microcracks the width of which changes in response to temperature gradients and hence differential thermal expansion coefficients.

International audience; Results of making surfaces of flexible cable conductors, used for solar arrays in geostationary orbit, charge dissipative by a specially developed method of ion-beam surface treatment with simultaneous surface renewal are presented. All flexible cable conductor surfaces, including those with rough morphology and foreign inclusions, achieved surface resistivity of ∼10–20 MΩ/sq. at room temperature and kept charge dissipation in a wide +/-150 °C space-related temperature range. A testing space qualification program confirmed all treated flexible cable conductors being resistant to thermal cycling and humidity, mechanically durable, and radiation resistant in geostationary orbit. All flexible cable conductors successfully survived 15 years space-equivalent geostationary orbit imitating testing. A comparison of beginning- and end-of-life characteristics of original and treated flexible cable conductors after this testing confirmed additional decrease of surface resistivity and almost equal final thermal-optical characteristics. Electrostatic discharge testing in a geostationary orbit charging testing facility demonstrated the long-lasting charge-dissipation properties of the treated flexible cable conductors, fully preventing them from building up critical charges in geostationary orbit environment, when a reliable grounding path is ensured for the surfaces.

To clarify the effects of space environment on mechanical properties of polymer, exposure experiments were conducted utilizing the International Space Station Russian Service Module. Poly‐ether‐ether‐ketone (PEEK) films under tensile stress were exposed to low Earth orbit (LEO) environment, and reference samples were irradiated with atomic oxygen (AO), electron beam (EB), and ultraviolet light (UV) in ground facilities. By comparing the results of flight and ground tests, the degradation behavior and the influential factors in LEO were investigated. The following results were obtained. (1) UV was found to be the harshest factor in LEO on tensile properties, since it decreased elongation to 15% of pristine sample after 46‐months exposure. (2) AO in LEO eroded the specimen surface with a cone‐like morphology and reduced the thickness; however, it had no significant effect on tensile properties. (3) EB irradiation in LEO had no measurable effects on the material properties.

Computer simulation and modeling of coupled heat and moisture transfer are becoming increasingly significant for accurate calculations of heat and moisture transfer. However, to solve their equations, the true component, λ, of apparent thermal conductivity, λapp, as a function of temperature, moisture content, and material structure is required. An approach to the development of a comprehensive database for λ is discussed. Its key feature is demonstrated by the development of a theoretical model for λ and λ app of two common building insulation materials — expanded polystyrene insulation and highly porous calcium silicate — for a wide range of temperature and moisture conditions.

Thermal optical properties, for example, solar absorptance a and thermal emittance e of thin plasma sprayed mullite coatings, were determined to assess the material's suitability for space application. The mullite coatings were developed in an attempt to find a new material for thermal protection systems as well as thermal barrier coatings for atmospheric reentry vehicles. All mullite coatings show the properties of a solar reflector and hence suggest a potential application as thermal control coating to protect space-bound structures from the effect of heating by solar radiation in the low Earth orbit. Preliminary space stability tests including atomic-oxygen resistance tests confirmed that the coatings show only negligible variations both in their mechanical and thermal optical properties under the conditions selected.

A program was initiated to further improve the space durability of nonconductive polymer-based paints and of conductive thermal control paints presently under development. The results of surface modification of both types of paints, including the ground-based testing and performance evaluation, are presented. Functional properties and performance characteristics, such as thermal optical properties and surface resistivity characteristics of pristine and treated materials, were verified. Tests results revealed that the successfully treated materials did not exhibit any mass loss or surface morphology change, thus, indicating good protection from the severe oxidative environment. It was demonstrated that the developed surface modification treatment can be applied successfully to charge dissipative paints.

A transient comparative exponential method (CEM) was developed to measure the thermal conductivity of thin ceramic coatings based on comparing the rate of heating during its exponential stage of a metal specimen with known thermal capacity without and with a coating. The experimental results were explained based on modelling the conductive heat transfer within the plasma-sprayed porous coating structure taking into account the contact heat barrier resistance (CHBR) between splat boundaries, and between substrate and coating as well as their dependence on the gas pressure within pores and microcracks as a function of the geometric altitude.

Results of surface modification treatment to improve space durability of main space-related thin polymer films, a lacing tape, and several organic-based thermal-control paints by a patented Photosil process are presented.Results of ground-based testing in an oxygen plasma asher and in a fast atomic-oxygen beam facility imitating low-Earth-orbit environment are also discussed. Characterization data before and after testing that include functional properties measurement, surface analyses, and durability evaluation are presented, and the protective mechanisms for Photosil treatment are discussed. Some of the samples that were treated in the program are similar to those in the Materials on International Space Station Experiment-1, being exposed now on the International Space Station. A number of space components including lacing tape and some external painted components of the Mobile Servicing System of the International Space Station were treated by Photosil, and the results will be discussed briefly.

Mid-energy monoenergetic conventional single-, dual-, or triple ion implantation, implantation with a MEVVA ion source, as well as Metal Plasma Immersion Ion Implantation have been used for the treatment of high-performance polymers at specially selected regimes, derived from the results of computer simulation. Testing of the implanted advanced polymers and carbon fiber reinforced composites has been performed in a Space Simulator for accelerated testing by exposure to fast ( E ∼2–3 eV) atomic oxygen beam, as well as by exposure to oxygen plasma, and ozone+UV. After an intermediate stage of surface conversion, the treated materials did not show any mass loss or surface morphology change, thus indicating high-quality protection from these severe oxidative environments. A variety of complementary surface analysis techniques, such as RBS, SIMS, XPS and SEM have been used to examine the surface content and structure of the modified subsurface layers.

Carbon nitride films were prepared by nitrogen ion assisted pulsed KrF excimer laser deposition of graphite onto Si(100) substrates. The energy of nitrogen ions was changed between 25 and 1500 eV. The transport ratio of carbon atoms to nitrogen ions at the substrate was 1.0. The dependence of the stoichiometry and formed chemical bonds on the nitrogen ion energy was investigated. The nitrogen content in prepared films increased with decreasing the nitrogen ion energy, and showed a constant value of 30 at.% below 200 eV. The peak position of C1s spectra as found by X-ray photoelectron spectroscopy (XPS) analysis shifted to higher binding energy with decreasing nitrogen ion energy. The N1s XPS peak was deconvoluted into three peaks with binding energies BE=398.3, 400.0 and 402.0 eV, which were assigned to sp 3 C–N and sp 2 C–N and N–N bondings, respectively. The ratio of sp 3 to sp 2 bonded nitrogen atoms increased with decreasing ion energy, and showed a maximum value in the energy interval between 50 and 75 eV. The carbon content with the sp 3 C–N bond type was estimated at 12.6 at.% from electron energy loss spectroscopy (EELS) analysis. The nitrogen content with the sp 3 C–N bond type was estimated at 18.0 at.% by XPS. The ratio of carbon to nitrogen atoms with sp 3 bonds was found to be 1.43 in the films grown at nitrogen ion energies of 50 eV, which is close to that of C 3 N 4 compound predicted as a superhard material.

Low energy high-dose Plasma Immersion Ion Implantation, combining both ion and recoil implantation (dynamic ion mixing), was used to enrich thin surface layers of high-performance polymers with an appropriate amount of specially selected reactive metal element such as Al. Both oxygen plasma and fast (E∼2–3 eV) atomic oxygen (FAO) beam have been used as aggressive environments for testing the implanted polymers. The modified materials successfully survived these test environments, including FAO, which is the main danger for carbon-based materials in space, in low Earth orbit. The retained doses of implanted and recoil implanted elements were controlled by RBS. The content, structure and morphology of the modified protective surface layers were examined by XPS and scanning electron microscopy (SEM). It was shown that protective oxide(s)-based surface structures were formed. Implantation and conversion conditions were found for which the appearance and important thermo-optical properties of treated polymer films, such as solar absorptance and thermal emittance, were practically unchanged.

Functional improvement of single-walled carbon nanotubes coated on polyimide Kapton HN was studied by means of cyclic cryogenic treatment. Immersing in liquid nitrogen at 77 K joining in heat annealing at 500 K induced the increase of D–G ratio and electrical conductivity in conjecture to the partial remedial junction with the coexisted stiction on surface. The coated thickness was deliberately able to adjust associated with cycling number of cryogenic treatment through the sequential detachment from the outmost layer owing to the axial shrunken effect by new atomic cross links at defects derived from the close bonding distance.

Spacecraft designers use polymers and polymer-based composite materials extensively in electrical, thermal, and structural applications to address both weight and performance demands. Without protection from the deleterious effects of the space environment, in particular hyperthermal atomic oxygen (HAO), these materials suffer accelerated erosion from chemical interaction and experience a loss of mass and deterioration of performance. High dose implantation at energies in the 10–100 keV range using ions of metal or semiconductor materials was used as a method of modifying the surface of these polymeric materials to produce changes that can yield dramatic improvements in space environmental durability. The results of this study show that computer modelling of the ion implantation process combined with reasonable fluence estimates give a good basis for the choice of implantation conditions. This study presents the results for high-performance materials including Kapton ® , Mylar ® , PEEK, Lexan ® , and PEEK/carbon fibre composites using X-ray electron spectroscopy, scanning electron microscopy, and other surface analysis techniques, before and after treatment. The results show that implantation of silicon and aluminum (singly, binary, or in combination with boron) or yttrium implantation produces a stable, protective oxide-based layer following exposure to HAO. The improvement in chemical resistance of these materials assures performance without deterioration in long duration space missions and shows promise for improvement in terrestrial performance in highly reactive oxidative environments.

A novel approach based on ion implantation has been developed and used to investigate the influence of a selection of metal and semi-metal ions or their combinations with selected non-metal elements, the implantation energy range, and ion fluencies, on the behaviour of implanted materials under fast atomic oxygen fluxes (FAO). The preferential conditions of single- or multiple-ion implantation in a number of high-performance polymers, graphite and composite materials were examined. Highly stable, oxidation- and erosion-resistant new surface structures were created on graphite, Kapton, PEEK and Mylar, and on carbon-fibre/PEEK composites by exposing the implanted materials to FAO in a unique atomic oxygen beam facility. A number of complementary surface analysis techniques such as RBS, XPS, SEM/EDS were used to study the content and structure of the modified surfaces, and their resistance to oxidation and erosion in FAO conditions.

Carbon nitride (CN) thin films were synthesized by combining vacuum arcs and plasma ion implantation techniques. Three methods were investigated: plasma ion implantation into carbon films deposited by anodic vacuum arcs (AAPII), continuous cathodic vacuum arc with plasma ion implantation (CAPII) and pulsed cathodic vacuum arc (PCA). The films were found to be amorphous by X-ray diffraction (XRD). X-Ray photoelectron spectroscopy (XPS) and Raman spectroscopy analysis indicated the formation of C N, C N and C≡N bonds. Calculations of the surface tension components (dispersion and polar) of the films using the contact angle measurement technique suggested the formation of covalent carbon-nitrogen bonds. The CN films exhibited improved adhesion relative to the pure carbon films as indicated by adhesion calculations and the reduction in interfacial tension between the films and the substrate. A hardness of 18.9 GPa was obtained by nanoindentation measurements for CN films with an N/C ratio of 0.135.

Spacecraft operating in the low Earth orbit (LEO) are exposed to an environment characterized by very low pressure, various atomic species, temperature extremes, ultraviolet (UV) radiation, electromagnetic radiation and atomic oxygen (AO), which is produced by the dissociation of molecular oxygen by UV radiation. The destructive influence of AO on polymer-based materials and composites and the synergistic effects between AO and other environmental factors have been dramatically demonstrated in LEO flights and ground-based simulators. This paper investigates the effects of contamination, structure and the synergism between temperature and AO fluence on polymer-based materials, and provides an overview of the recent developments in the design and use of protective coatings for polymer and composite materials in the LEO environment and their testing in ground-based space environment simulators. Three trends in protective coatings research are identified and discussed: (a) the improvement of technologies for high-performance oxide-based coatings; (b) self-healing coatings based on special semi-organic polymers; (c) protective multilayered structures. An evaluation is made of the properties and behaviour of different protective coatings on the polymers and composite materials used in spacecraft applications.

From a comprehensive analysis of erosion data for materials exposed to low-Earth-orbit space environment, to fast atomic-oxygen beams, and in plasma facilities it is shown that different correlations can be found between the thermal and hyperthermal atomic-oxygen erosion yield of hydrocarbon polymers and their chemical structure and content. Correlations have been found of the hyperthermal atomic-oxygen erosion yield of many polymeric materials in flight experiments with their inverse mass density of effective (not bonded with oxygen) carbon atoms, and with their degree of aromaticity. These correlations were used to identify the rate-limiting factors of erosion processes and to predict the erosion rate for polymer-based materials in low Earth orbit. The first correlation was not found in the interaction of thermal atomic oxygen with a number of polymers, and the second is strongly pronounced. The results are explained on the basis of physical and chemical processes affecting differently the erosion rates of polymers by thermal and by fast atomic oxygen. Subthreshold bombardment-induced and -enhanced degradation and surface chemical etching are proposed to be the major mechanisms of erosion by fast atomic oxygen.

Surface properties of Kapton® were analysed after different exposures to ground state fast atomic oxygen (FAO) and vacuum ultraviolet radiation in the atomic oxygen beam facility at the University of Toronto Institute for Aerospace Studies X-ray photoelectron spectroscopy, scanning electron microscopy and contact angle measurements were used to characterize the chemical and physical changes to the surfaces of the materials analysed. The most important changes in the surface chemistry of Kapton induced by the various exposures to FAO were oxidative degradation of the polymer and substantial changes in supermolecular organization and morphology of the surface layer. A very weak adhesion of the rough top layer to the original Kapton has been observed after an atomic oxygen irradiation with a total fluence of 1.3 × 10 21 atoms cm −2 , which is comparable to some low earth orbit (LEO) exposures. Comparison was made between pristine samples and the cleaned surface of samples that had been exposed in the atomic oxygen beam facility and in the LEO environment. An ageing effect was observed in the surface layer of exposed samples after a prolonged storage. For several polymer materials, a correlation was found between the erosion yield when exposed to FAO and the dispersion component of the surface tension of the pristine material

Many polymer-based materials degrade in low earth orbit (LEO), mainly due to the damaging environmental effects of hyperthermal or fast atomic oxygen of energy E ∼ 5 eV and solar vacuum ultraviolet radiation. Fast atomic oxygen fluxes of similar energies are generated now in ground-based facilities that are used for accelerated testing of materials. This paper presents a brief overview of the effects of interaction of fast atomic oxygen fluxes with polymer-based materials in the LEO space environment and in ground-based simulators, and discusses a few possible applications of fast atomic oxygen fluxes. Such applications can lead to considerable advantages over plasma treatment, aimed at improvement of adhesion-related and optical properties of polymer-based materials, high-quality precise photoresist etching and passivative oxidation of advanced semiconductor materials, and modified or entirely new surface properties of biomaterials and chemical sensors.

Under a 2-year program funded by the Canadian Space Agency, ITL Inc. is developing and manufacturing a Planetary Environmental Simulator/Test Facility to be used for testing and life-time evaluation of candidate spacecraft materials and mechanical systems, space suits, and planetary mission crew habitats. The basic facility will include a vacuum chamber and a number of environmental sources to simulate the planetary surface environments, including dust particles, UV radiation, temperature conditions and darkness, as well as simple fixtures and test rigs enabling to conduct mechanical testing of planetary rovers’ components.

This paper is an overview of instrumentation developed and created by ITL Inc. for simulated testing and performance evaluation of spacecraft materials, structures, mechanisms, assemblies and components in different space and planetary environments. The LEO Space Environment Simulator allows simulation of the synergistic effect of ultra-high vacuum conditions, 5 eV neutral atomic oxygen beams, Vacuum-Ultraviolet (VUV) and Near-Ultraviolet (NUV) radiation, and temperature conditions. The simulated space environmental conditions can be controlled in-situ using a quadruple mass-spectrometer, Time-of-Flight technique, as well as Quartz Crystal Microbalance sensors. The new NUV System is capable of delivering an NUV power intensity of up to 10 Equivalent Suns. The design of the system uses horizontal orientation of the 5 kW Mercury lamp, focusing of NUV radiation is achieved due to a parabolic reflector. To address the Lunar/Martian surface environments, the Planetary Environmental Simulator/Test Facility has been developed and built to allow for physical evaluation of the effects of the Lunar/Martian dust environments in conjunction with other factors (ultra-high vacuum or planetary atmospheric conditions, VUV/NUV radiation, thermal cycling, and darkness). The ASTM E 595/ASTM E 1559 Outgassing Test Facility provides the means for the outgassing test of materials with the objective to select materials with low outgassing properties for spacecraft use and allows to determine the following outgassing parameters: Total Mass Loss, Collected Volatile Condensable Materials, and Water Vapor Regained.

Surface engineering techniques are being used extensively in the aerospace and space industries as well as a variety of other industries to develop, maintain, or change a wide range of functional properties, including physical, chemical, electrical, electronic, magnetic, mechanical, wear-resistant and corrosion-resistant properties. An overview of the present, state-of-the-art, situation in the field of surface modification of space materials is presented. A number of surface modification technological solutions that differ from the traditional protective coating approaches are discussed that change the surface properties of treated materials thus protecting them from the hazards of low earth orbit (LEO) and geostationary orbit (GEO) environments or impairing new functional properties to space materials used in LEO/GEO, with examples of their testing, characterization and applications provided. Keywords: surface modification; space environment; low earth orbit; photosil; Materials for LEO and GEO orbits; surface engineering; space materials; thermal control paints; ion implantation; implantox; carbosurf; ion-beam texturing; charge dissipative polymer surfaces

An analysis was done of changes in the crystallinity, the oxidation induction time (OIT) and the degree of surface oxidation of polyethylene thin films before and after gas-phase oxidative surface modification. Various surface treatments were performed which allowed to differentiate between oxidation of the bulk and the surface. It was shown that for a full characterization of oxidation processes in solid films all three parameters (degree of crystallinity, surface energy and OIT) needed to be taken into account. The correlations between the degree of crystallinity and OIT can be used as an indicator of the extent of bulk modification. The correlations between the surface energy and the OIT can be used as an indicator of surface oxidation.

The meteoroid population in near‐Earth space is typically broken down into two components: shower meteoroids which orbit in collimated streams, and the older sporadic meteoroids which have been dispersed into a much broader uncollimated distribution of orbits. The sporadic meteors dominate the meteoroid flux at Earth in the size range of those particles of the most of the risk to spacecraft (approximately 100 microns to 1 cm). We describe the results of numerical simulations of the sporadic meteoroid complex by full physical modeling of meteoroids from ejection from their parent body through their perturbation by planets and radiation forces though the end of their lives through collision or ejection from the solar system. This model together with comparison with optical and radar measurements of meteoroid fluxes in near Earth space will allow improved assessment of the risk to spacecraft in near‐Earth space from the sporadic complex.

Effects of atomic oxygen (AO) on mechanical properties of polyimide films were investigated using surface topography observations and tensile tests. The ITO‐coated polyimide films, which are expected to have a high durability against AO attacks, were also evaluated. Surfaces of polyimide films irradiated by AO were deeply eroded, exhibiting a rough texture. The roughness developed as the AO fluence increased. Tensile strength and elongation of the polyimide films degraded after AO irradiation tests. In addition, that degradation became marked concomitantly with increased AO fluence. These results indicate that development of surface roughness can degrade mechanical properties of polyimide films. In contrast, surfaces of ITO‐coated polyimide films remained flat and were hardly affected by AO irradiation. Nevertheless, the tensile strength and elongation of ITO‐coated polyimide films were decreased by AO irradiation. Such degradation resulted from undercut cavities formed by AO erosion at the defects sites of ITO coating.

Polyimides are widely used as spacecraft external surfaces materials. They are exposed to atomic oxygen (AO), which is the main constituent of a residual atmosphere at low Earth orbit (LEO) and should be protected from the space harsh environment. This work presents an innovative approach to applying a protective coating on Kapton polyimide using liquid‐phase deposition (LPD) and shows its effectiveness in reduction of AO‐induced surface erosion.Titania coatings, 100 nm thick, were deposited on Kapton films by LPD using an aqueous solution of a metal‐fluoride complex and boric acid at near ambient conditions. Adherent, crack‐free, coatings have been obtained by optimization of the deposition conditions, the substrate surface pre‐treatment procedure and post‐deposition drying. Characterization of the oxide coating included Atomic Force Microscopy (AFM) in tapping and nano‐indentation modes, Environmental Scanning Electron Microscopy (ESEM), and X‐ray Photoelectron Spectroscopy (XPS).The durability of the t...

A space materials exposure experiment was condcuted on the exterior of the Russian Service Module (SM) of the International Space Station (ISS) using the Micro‐Particles Capturer and Space Environment Exposure Device (MPAC&SEED) of the Japan Aerospace Exploration Agency (JAXA). Results reveal artificial environment effects such as sample contamination, attitude change effects on AO fluence, and shading effects of UV on ISS. The sample contamination was coming from ISS components. The particles attributed to micrometeoroids and/or debris captured by MPAC might originate from the ISS solar array. Another MPAC&SEED will be aboard the Exposure Facility of the Japanese Experiment Module, KIBO Exposure Facility (EF) on ISS. The JEM/MPAC&SEED is attached to the Space Environment Data Acquisition Equipment‐Attached Payload (SEDA‐AP) and is exposed to space. Actually, SEDA‐AP is a payload on EF to be launched by Space Shuttle flight 2J/A. In fact, SEDA‐AP has space environment monitors such as a high‐energy particle monitor, atomic oxygen monitor, and plasma monitor to measure in‐situ natural space environment data during JEM/MPAC&SEED exposure. Some exposure samples for JEM/MPAC&SEED are identical to SM/MPAC&SEED samples. Consequently, effects on identical materials at different positions and operation periods of ISS will be evaluated. This report summarizes results from space environment monitoring samples for atomic oxygen analysis on SM/MPAC&SEED, along with experimental plans for JEM/MPAC&SEED.

Three plasma processing systems based on PII technique have been used in the improvement of surface properties of different materials important for aerospace and space applications. Metal plasma PII of Al and Mg was used for surface protection of polymers used in space such as Kapton, Mylar and polyethylene. Al alloys were treated with nitrogen PII for improved resistance to corrosion aiming at aerospace applications. A rigid polymer UHMWPE was also treated in a nitrogen PII to produce a protective layer with DLC. Although not very light, SS304 stainless steel components are being used in a imaging camera in space, and some components made of this material showed endurance to vibration tests after nitrogen PII, therefore being qualified for on‐board application.

The effect on the reflective spectra of heat treatment and modification of ZnO pigments by 1–30 wt.% ZrO2 and Al2O3 nanoparticles has been investigated before and after irradiation by 100 keV protons with a fluence of 5×1015 cm−2. It is established that with the optimum concentration of 5 wt.% nanoparticles and the temperature of 800° C a 20% increase in the radiation stability is observed for the modified ZnO pigment in comparison with the not modified pigment. The decrease of absorption in the modified pigments is determined by the decrease of the intensity of the absorption bands of the zinc vacancies (Vzn−), oxygen vacancies (Vo+) and donor‐acceptor couples (Vzn‐−Zni0).

Radiation‐induced conductivity (RIC) model is used in surface charging simulations to calculate the dielectric potential. The RIC model including continuity equation of current, Poisson equation and trapped charge rate equation aims at accurately simulate the surface charging process while taking into consideration the flux and dose rate profiles of injected electrons. Compared with the widely used parallel resistor‐capacitor simplification in the equivalent circuit model, it results for a polyimide in a similar balance surface potential but a different charging process. It is also implemented into the 1‐D Particle‐In‐Cell (PIC) code to compare with corresponding results of. The comparison between the results from the RIC and NASA/MATCHG shows a 50% difference for the surface potential of polyimide. In order to validate the model, ground experiments using electron beam were conducted. The 25 μm thick polyimide film was exposed to an electron beam with energy ranging from 10 keV to 30 keV and a flux densit...

This paper describes successful results obtained by a new type of plasma source, named as Vaporization of Solid Targets (VAST), for treatment of materials for space and aerospace applications, by means of plasma immersion ion implantation and deposition (PIII&D). Here, the solid element is vaporized in a high pressure glow discharge, being further ionized and implanted/deposited in a low pressure cycle, with the aid of an extra electrode. First experiments in VAST were run using lithium as the solid target. Samples of silicon and aluminum alloy (2024) were immersed into highly ionized lithium plasma, whose density was measured by a double Langmuir probe. Measurements performed with scanning electron microscopy (SEM) showed clear modification of the cross‐sectioned treated silicon samples. X‐ray photoelectron spectroscopy (XPS) analysis revealed that lithium was implanted/deposited into/onto the surface of the silicon. Implantation depth profiles may vary according to the condition of operation of VAST. One direct application of this treatment concerns the protection against radiation damage for silicon solar cells. For the case of the aluminum alloy, X‐ray diffraction analysis indicated the appearance of prominent new peaks. Surface modification of A12024 by lithium implantation/deposition can lower the coefficient of friction and improve the resistance to fatigue of this alloy. Recently, cadmium was vaporized and ionized in VAST. The main benefit of this element is associated with the improvement of corrosion resistance of metallic substrates. Besides lithium and cadmium, VAST allows to performing PIII&D with other species, leading to the modification of the near‐surface of materials for distinct purposes, including applications in the space and aerospace areas.

Aluminum film reflectors can yield a high reflectance over a broad wavelength region, and have been widely used in the spacecraft optical instruments for high quality optical applications. The reflectors, however, could deteriorate under the irradiation by charged particles in the Earth radiation belt. To understand the deterioration mechanisms, the change in surface morphology of an Al film reflector irradiated with 60 keV protons was studied in liquid nitrogen cooled vacuum environment. Proton irradiation affected strongly the Al film reflectors forming a rough surface covered with hillocks and valleys that caused an increase in the RMS roughness and light scattering that, in turn, contributed to the decrease of specular reflectance in UV and visible wavelength ranges. The studies on the changes in surface morphology of Al film reflectors induced by proton irradiation would help to understand the damage mechanism and predict the performance evolution of optical equipment used in spacecrafts under space ...

Atomic oxygen (AO) is among the predominant factors in Low Earth Orbit (LEO) space environment. Ground‐based laboratory AO exposure testing was performed to investigate interaction between atomic oxygen and materials that were intended for use in future missions on LEO spacecraft. Two types of adhesive materials, i.e., E‐32 epoxy and GS414 silicone were tested in Atomic Oxygen Test Facility at the Beijing Institute of Spacecraft Environment Engineering (BISEE). The effective atomic oxygen fluence in the conducted tests was approximately 1.4×1021 atoms/cm2 which is close to the fluence of a two‐year exposure in LEO orbit. Significant mass losses of epoxy adhesive materials were detected after the exposure to atomic oxygen, but relatively small mass changes were found in silicone samples. The erosion yields of epoxy samples were from 3.2×10−24 cm3/atom to 3.8×10−24 cm3/atom. Surface bleaching by atomic oxygen was found in epoxy samples. The surface on silicone sample remained glossy after AO exposure. Both ...

This report presents the results of an investigation of thermo‐optical characteristics, i.e. the total solar absorptance, αs and solar emittance, e of thermal control coatings (TCC) exposed to the space environment at a geostationary orbit (GEO). Experiments results from samples that were flown on space vehicles (SV) “Yamal‐100” and “Yamal‐200” for 8 and 4 flight years, respectively, are presented here. The results from experiments flown for 6 and 2 flight years were presented in an earlier article [1].The αs and e characteristics were measured by a calorimetric method through monitoring the temperatures of the coating samples that were used as microcalorimeters (MC) and a mathematical treatment of the temperature data. The temperature sensors were attached to the back side of the flown samples.

As part of the Materials on The International Space Station Experiment (MISSE), aromatic polymers containing phenylphosphine oxide groups were exposed to low Earth orbit for ∼4 years. All of the aromatic polymers containing phenylphosphine oxide groups survived the exposure despite the high fluence of atomic oxygen that completely eroded other polymer films such as Kapton® and Mylar® of comparable or greater thickness. The samples were characterized for changes in physical properties, thermal/optical properties surface chemistry, and surface topography. The data from the polymer samples on MISSE were compared to samples from the same batch of material stored under ambient conditions on Earth. In addition, comparisons were made between the MISSE samples and those subjected to shorter term space flight exposures. The results of these analyses will be presented.

MoS2+Graphite composite coatings were synthesized onto 2024 aluminum alloy substrates by sputtering. The friction and wear test were performed at different environment pressures in vacuum using a ball‐on‐disk tribometer. The worn surface of the coating was examined by scanning electron microscopy (SEM). The results show that the friction coefficients and wear rate are increasing with increased environment pressure. A second surface layer was formed on the worn surface, that is harder than the original surface. The hardness of this second surface layer is decreased with increasing environment pressure.

We studied measurement of secondary electron emission (SEE) of metal and insulating materials used for satellite thermal insulation or other such purposes. The SEE yield measurement is very important for analyzing charge accumulation on satellite surfaces for a space environment because electron emission related to irradiated electrons influences the amount of surface charge. Therefore, we tried to measure the SEE yield. Furthermore, we must consider degradation phenomena of surface materials for spacecraft caused by radioactive rays. According to the degradation of materials, those SEE yields might change compared to a non‐degradation sample. Therefore, we tried to measure the SEE yields of surface materials for spacecraft which are treated using the degradation process. For preparing a degradation sample, those samples were irradiated by an electron beam and UV to simulate degradation in a space environment. We take three irradiation conditions for electron beam and UV irradiation that related with GEO ...

This paper describes the study framework for material property measurements related to spacecraft charging, methods, and measurement results. This work specifically addresses analyses and measurements of surface resistivity, volume resistivity, and the dielectric constant. We also explain measurements of secondary electron and photoelectron emissions in this framework.This review is based on joint experimental studies conducted for the Japan Aerospace Exploration Agency (JAXA) at the High Energy Accelerator Research Organization (KEK), at the Musashi Institute of Technology and at the Saitama University to investigate the relation to spacecraft charging. This report introduces a summary of some typical measurement results following a brief explanation of the measurement project.

The Materials International Space Station Experiment 2 (MISSE 2) Polymer Erosion and Contamination Experiment (PEACE) polymers were exposed to the environment of low Earth orbit (LEO) for 3.95 years from 2001 to 2005. There were forty‐one different PEACE polymers, which were flown on the exterior of the International Space Station (ISS) in order to determine their atomic oxygen erosion yields. In LEO, atomic oxygen is an environmental durability threat, particularly for long duration mission exposures. Although space flight experiments, such as the MISSE 2 PEACE experiment, are ideal for determining LEO environmental durability of spacecraft materials, ground‐laboratory testing is often relied upon for durability evaluation and prediction. Unfortunately, significant differences exist between LEO atomic oxygen exposure and atomic oxygen exposure in ground‐laboratory facilities. These differences include variations in species, energies, thermal exposures and radiation exposures, all of which may result in different reactions and erosion rates. In an effort to improve the accuracy of ground‐based durability testing, ground‐laboratory to in‐space atomic oxygen correlation experiments have been conducted. In these tests, the atomic oxygen erosion yields of the PEACE polymers were determined relative to Kapton H using a radio‐frequency (RF) plasma asher (operated on air). The asher erosion yields were compared to the MISSE 2 PEACE erosion yields to determine the correlation between erosion rates in the two environments. This paper provides a summary of the MISSE 2 PEACE experiment; it reviews the specific polymers tested as well as the techniques used to determine erosion yield in the asher, and it provides a correlation between the space and ground‐laboratory erosion yield values. Using the PEACE polymers’ asher to in‐space erosion yield ratios will allow more accurate in‐space materials performance predictions to be made based on plasma asher durability evaluation.