This pdf file contains the front matter associated with SPIE Proceedings Volume 7794, including Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Room Temperature Vulcanized (RTV) materials, such as silicone adhesives, are commonly used to bond components of communication satellites and other types of spacecraft. The elevated satellite operating temperature causes the unused catalyst material in the RTV to volatize, which can then re-deposit or condense onto other spacecraft surfaces. This Volatile Condensable Material (VCM) can condense onto optically-sensitive spacecraft surfaces and significantly alter their original, beginning-of-life (BOL) optical properties, such as solar absorptance and emittance, causing unintended performance loss of the spacecraft. Knowledge of the optical impact of VCM's is therefore a major concern of spacecraft designers and spacecraft-contamination engineers. In view of this we have employed in-situ spectroscopic ellipsometry to monitor in real time the optical constants of the condensed effluent of RTV-566, SCV-2590-2 and SCV-2590 as function of condensation temperature from 120 K to 180 K. The film is condensed directly on to a QCM crystal. Thus the QCM generated deposition trajectory and thickness can be correlated to the optical trajectory and thickness, yielding the film density. We will present the optical constants, n and k, as a function the condensation temperature.

As Observatories are designed, built, tested, and launched, they occasionally have unanticipated incidents which can impede the progress towards launch, or affect the final product of a satellite mission. These incidents have the potential to cause minor inconveniences, extra paperwork, schedule hits, extra analysis or in the worst case, performance degradation. The Solar Dynamics Observatory (SDO) experienced various types of incidences in different phases of build and launch. The purpose of this study is to discuss the major contamination-related lessons learned during the design, production, testing, and launch of the Solar Dynamics Observatory to help future programs avoid similar incidents.

Extremely tight thermal control property degradation allowances on the vapor-deposited, gold-coated IEC baffle surface, made necessary by the cryogenic JWST Observatory operations, dictate tight contamination requirements on adjacent surfaces. Theoretical degradation in emittance with contaminant thickness was calculated. Maximum allowable source outgassing rates were calculated using worst case view factors from source to baffle surface. Tight requirements pushed the team to change the design of the adjacent surfaces to minimize the outgassing sources.

The European Space Agency ESA is running a series of earth observation missions. In order to perform global windprofile observation based on Doppler-LIDAR, the satellite ADM-Aelolus will be launched in April 2011 and injected into an orbit 400 km above Earth's surface. ADM-Aeolus will be the first satellite ever that is equipped with a UV-laser (emitting at 355 nm) and a reflector telescope. At LLG, a setup was developed that allows monitoring transmission, reflection and fluorescence of laser-irradiated optical components, in order to assess their possible optical degradation due to radiation-induced contaminant deposition in orbit. For both a high-reflecting mirror and an anti-reflective coated window long-term irradiation tests (up to 500 million laser pulses) were performed at a base pressure < 10^-9 mbar, using a XeF excimer laser (wavelength 351 nm, repetition rate 1kHz). At this, samples of polymers used inside the satellite (insulators for cabling, adhesives, etc.) were installed into the chamber, and the interaction of their degassing with the sample surfaces under laser irradiation was investigated. Various paramters were varied including pulse repetition rate, view factor and coatings. Optical degradation associated with contaminant adsorption was detected on the irradiated sample sites.

The Aerosol Polarimetery Sensor (APS) is a nadir viewing, along-track observing, continuously operating electro-optical polarimeter designed to measure earth and atmosphere scene spectral radiance in the visible (VIS) to short wave infrared (SWIR) spectrum from an altitude of 705 km to permit collection of data for retrieval of operational Environmental Data Records (EDRs). APS performance can be degraded due to light scatter, transmission, or reflectance changes caused by contamination. Molecular films can cause scattering as well as spectrally selective absorption and reflectance degradation. At short wavelengths, the molecular films may also create polarization changes. Raytheon developed and implemented a contamination control program that ensured the APS sensor complied with cleanliness requirements. Representative cleanliness monitoring results and lessons learned from the sensor integrated and tested at Space and Airborne Systems El Segundo and Santa Barbara Remote Sensing (SBRS) are also presented.

Brush and forest fires, both naturally occurring and anthropogenic in origin, in proximity to space flight hardware processing facilities raise concerns about the threat of contamination resulting from airborne particulate and molecular components of smoke. Perceptions of the severity of the threat are possibly heightened by the high sensitivity of the human sense of smell to some components present in the smoke of burning vegetation. On August 26th, 2009, a brushfire broke out north of Pasadena, California, two miles from the Jet Propulsion Laboratory. The Station Fire destroyed over 160,000 acres, coming within a few hundred yards of JPL. Smoke concentrations on Lab were very heavy over several days. All Lab operations were halted, and measures were taken to protect personnel, critical hardware, and facilities. Evaluation of real-time cleanroom monitoring data, visual inspection of facilities, filter systems, and analysis of surface cleanliness samples revealed facility environments and hardware were minimally effected. Outside air quality easily exceeded Class Ten Million. Prefilters captured most large ash and soot; multi-stage filtration greatly minimized the impact on the HEPA/ULPA filters. Air quality in HEPA filtered spacecraft assembly cleanrooms remained within Class 10,000 specification throughout. Surface cleanliness was minimally affected, as large particles were effectively removed from the airstream, and sub-micron particles have extremely long settling rates. Approximate particulate fallout within facilities was 0.00011% area coverage/day compared to 0.00038% area coverage/day during normal operations. Deposition of condensable airborne components, as measured in real time, peaked at approximately 1.0 ng/cm2/day compared to 0.05 ng/cm2/day nominal.

Mechanisms for molecular contaminant droplet formation are investigated. The tendency for droplet formation is evaluated in terms of the surface tension of the liquid-like outgassed species and the surface energy of the collector. Results are presented indicating that VUV irradiation of the surface prior to contaminant deposition eliminates some droplet formation completely. This finding is discussed in terms of the removal of hydrocarbon and carbonyl-structured compounds from oxidized silicon surfaces.

Contamination control is an important driver in the success of most space missions with more and more stringent constraints of quality and reliability : indeed, most of spacecrafts having equipments sensitive to molecular contamination like optics or detectors, the risk of damage and performance loss of such sensitive surfaces has to be considered as a real concern and treated in the early phases of the development of an instrument. Since molecular contaminants result mainly from outgassing of polymers, bakeouts under vacuum are required at the lowest possible product level in order to reduce the contamination potential of selected materials. Nevertheless, this conventional method takes time and could be relatively expensive. Then the use of low cost porous materials has appeared as an interesting alternative to trap organic contaminants, taking advantage of their controlled adsorption characteristics in channels of molecular dimensions. A recent PhD study has showed that, compared to other materials, zeolites widely used in catalysis and separation processes have great potential in such applications. Theoretical and experimental investigations have demonstrated the feasibility with three types of highly efficient zeolites. This paper reports on further development related to the preparation of uniform, homogeneous thin films of pure zeolitic materials deposited on different substrates (glass, carbon fibers...). Kinetics and sorption capacities of several representative outgassed species on these films have been investigated by thermogravimetric analyses and the results compared with the efficiency of corresponding powder materials. A discussion on the potential locations of such molecular adsorbers inside optical instruments is proposed.

As mission, satellite, and instrument performance requirements become more advanced, the need to control adverse onorbit molecular contamination is more critical. Outgassed materials within the spacecraft have the potential to degrade performance of optical surfaces, thermal control surfaces, solar arrays, electronics, and detectors. One method for addressing the outgassing of materials is the use of molecular adsorbers. On Goddard Space Flight Center missions such as Hubble Space Telescope (HST), Tropical Rainfall Measuring Mission (TRMM), and SWIFT, Zeolite-coated cordierite molecular adsorbers were successfully used to collect and retain outgassed molecular effluent emanating from spacecraft materials, protecting critical contamination sensitive surfaces. However, the major drawbacks of these puck type adsorbers are weight, size, and mounting hardware requirements, making them difficult to incorporate into spacecraft designs. To address these concerns, a novel molecular adsorber coating was developed to alleviate the size and weight issues while providing a configuration that more projects can utilize, particularly contamination sensitive instruments. This successful sprayable molecular adsorber coating system demonstrated five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was refined and a procedure for spray application was developed. Samples were spray coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. The tested formulation passes coating adhesion and vacuum thermal cycling tests between +140 and -115C. Thermal radiative properties are very promising. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate coatings.

Contamination Control Engineering practices are performed on NASA satellite missions at the Goddard Space Flight Center (GSFC) in order to control adverse effects of contamination on sensitive surfaces such as, optics, sensors, and thermal control surfaces. The primary goal of this research is to determine how inspection tools are used, and how their capabilities can be verified. The research was accomplished by investigating the following tools: the Dino-Lite hand held microscope; a video Borescope, a portable bi-directional reflectance distribution function (BRDF) scatterometer; and Contamination Field Kits, suitcases which carry the very tools for inspection and verification within them. A secondary goal is to further develop an existing purge suitcase for the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) instruments on the Landsat Data Continuity Mission (LDCM). The purge suitcase is used as a contamination mitigation technique to keep the instruments dry and clean.

Ball Aerospace and Technologies Corporation (BATC) developed a unique thermal control coating named Ball InfraRed Black™ (BIRB™). The proprietary coating was developed for use on spacecraft thermal radiators, but also has application to terrestrial cryogenic and vacuum systems. The unique morphology and large effective surface area of BIRB™ generates superior cryogenic emissivity properties. Independent testing performed at NASA Goddard Spaceflight Center confirms the emissivity at 50K has been documented to be 40% greater than typical thermal control coatings, generating enhanced performance and/or substantial mass savings. The coating proves to be extremely durable and cleanable when properly handled. BIRB™ has the additional benefit of being static-dissipative, making it ideal for direct exposure to the space environment. The critical thermal, physical, and mechanical properties for BIRB™ have been measured. The coating is qualified for spaceflight, demonstrating outstanding adhesion after thermal cycling and vibration testing. Contamination control properties have been optimized, achieving low total outgassing rates as measured by testing in accordance with ASTM E1159 and demonstrating particle cleanliness meeting level 200 as defined by IEST-STD-CC1246. BIRB™ has been qualified for use on several BATC flight programs, including applications for large cryogenic radiators.

We have developed surface chemical modification processes which when applied to a variety of surfaces renders the surfaces resistant to particulate contamination. Chemically modified surfaces are shown to shed particles at a dramatically higher level as compared to native surfaces. This is demonstrated on a variety of surfaces that include optics, polymers, metals and silicon. The adhesive force between lunar stimulant particles (JSC-1AF) and black Kapton is measured to decrease by 95% when the black Kapton surface is chemically modified. The chemical modification process is demonstrated to not change the surface roughness of a smooth silicon wafer while decreasing particle affinity. The optical properties of chemically modified surfaces are reported. The surface modification process is robust and stable to aggressive cleaning. The particle shedding properties of chemically modified surfaces are retained after simulated extraterrestrial vacuum ultra-violet light exposure and temperature excursions to 140°C. This technology has the potential to provide a robust passive particle mitigation solution for optics, mechanical systems and particle sensitive applications.

Dust and ice contamination is a serious problem for equipment and vehicles for air and space mission applications. Dust contamination gathers on photonic sensors inhibiting motion and data gathering. Photonic devices that require transparency to light for maximum efficiency, such as solar photovoltaic power systems, video cameras and optical or infrared detectors, can be seriously affected by dust accumulation. The lunar thermal and radiation environment also pose unique challenges because of its large temperature variations and its interaction with the local plasma environment and solar UV and X-rays induced photoemission of electrons. Superhydrophilic materials are composed of polar molecules and have been used to defog glass, enable oil spots to be swept away easily with water, as door mirrors for cars and coatings for buildings. Hydrophobic molecules tend to be non-polar and thus prefer other neutral molecules and nonpolar solvents. Hydrophobic molecules often cluster together. Hydrophobic surfaces contain materials that are difficult to wet with liquids, with superhyrophobic surfaces having contact angles in excess of 150° (the equilibrium angle of contact of a liquid on a rigid surface where liquid, solid and gas phases meet). This paper presents an overview of the fundamental forces (van der Waals) which allows certain contamination to adhere to critical photonic surfaces and the various passive coatings phenomenology (hydrophilic to hydrophobic) that is used to minimize this contamination.

The "Lotus" dust mitigation coating is a new technology that is currently being developed and tested, at NASA Goddard Space Flight Center (GSFC), as a countermeasure for addressing dust accumulation issues for long-duration human space exploration. This coating sheds dust particles utilizing anti-contamination and self-cleaning properties that minimize dust accumulation on spacecraft surfaces. Shedding of dust particles is accomplished by reducing the surface energy and the amount of surface available for attachment. The Lotus coating is designed to preserve optimal long-term performance of critical spacecraft surfaces and systems, while minimizing and/or eliminating dust accumulation. NASA is exceedingly interested in simplistic and innovative ways to mitigate dust accumulation while minimizing the impact to spacecraft mass and power requirements. Preliminary research and development indicates that the Lotus Coating has the potential to be a viable passive tool for mitigating dust on: radiator surfaces, solar array panels, habitation airlock walls, mechanism shields, astronaut EVA suits, and astronaut visors exterior coating.

Previous studies have correlated the particle fallout rates within cleanrooms to MIL-STD-1246 cleanliness levels. Unfortunately "cleanliness levels" are not linear and do not lead to easily understood increases with respect to either cleanroom class or time. Additionally, cleanroom "class" is rarely static but varies throughout the processing flow in accordance with the activity levels. A numerical evaluation of the particle fallout normalized to area coverage demonstrates a correlation that is directly proportional to both cleanroom class and exposure time, yielding a simple Class-Hour formulation. Application of this formulation allows for dynamic monitoring of the projected fallout rates using a standard air particle counter. The theoretical results compare favorably with historical data and recent studies.

Purging is a common scheme to protect sensitive surfaces of payloads and spacecraft from airborne contaminant intrusion during ground assembly, integration, and launch vehicle encapsulation. However, the purge for space volumes must be occasionally interrupted. Thus it is important to gain insights into the transport of ambient particles penetrating through vent holes and entering the interior of a confined space system, such as a space telescope, during a purge outage. This study presents experimental work performed to measure time-dependent aerosol concentration changes during a purge outage. The laboratory results from the aerosol experiments were compared with a mass balance based mechanistic model which had been experimentally validated for aerosols ranging from 0.5 to 2 μm. The experimental data show that the steady-state aerosol concentration inside a simulated space telescope (SST) is governed by the surrounding particle concentration, SST air exchange rate, and the particle deposition rate.

The National Aeronautics and Space Administration (NASA) is launching a bold and ambitious new space initiative. A significant part of this new initiative includes exploration of new worlds, the development of more innovative technologies, and expansion our presence in the solar system. A common theme to this initiative is the exploration of space beyond Low Earth Orbit (LEO). As currently organized, NASA does not have an Agency-level office that provides coordination of space environment research and development. This has contributed to the formation of a gap between spaceflight environments knowledge and the application of this knowledge for multi-program use. This paper outlines a concept to establish a NASA-level Applied Spaceflight Environments (ASE) office that will provide coordination and funding for sustained multi-program support in three technical areas that have demonstrated these needs through customer requests. These technical areas are natural environments characterization and modeling, materials and systems analysis and test, and operational space environments modeling and prediction. This paper will establish the need for the ASE, discuss a concept for organizational structure and outline the scope in the three technical areas.

This paper describes a MATLAB-based molecular transport model developed for modeling contamination of spacecraft and optical instruments in space. The model adopts the Gebhart inverse-matrix theory for thermal radiation to analyze mass (molecular) transfer due to direct and reflected flux processes by balancing the mass fluxes instead of heat fluxes among surfaces with prescribed boundary conditions (contamination sticking fractions). The model can easily input view factor results from current thermal tools as well as measured outgassing data from ASTM E 1559 tests or vacuum bake-outs of flight components. Application examples of a geosynchronous satellite and an optical telescope are given to demonstrate versatile applications of the developed model.

NASA's Magnetospheric MultiScale (MMS) is an unmanned constellation of four identical spacecraft designed to investigate magnetic reconnection by obtaining detailed measurements of plasma properties in Earth's magnetopause and magnetotail. Each of the four identical satellites carries a suite of instruments which characterize the ambient ion and electron energy spectrum and composition. Some of these instruments utilize high-voltage microchannel plates and are sensitive to particulate contamination. In this paper, we analyze the transport of particulates during pre-launch, launch and ascent events, and use the analysis to obtain quantitative predictions of particle contamination on the instruments. Particle redistribution is calculated by considering the gravitational and aerodynamic forces acting on the particles.

As a spacecraft undergoes ascent in a launch vehicle, its pressure environment transitions from one atmosphere to high vacuum in a matter of minutes. Venting of internal cavities is necessary to prevent the buildup of pressure differentials across cavity walls. Opposing the need to vent these volumes freely into space are thermal, optical, and electrostatic requirements for limiting or prohibiting the intrusion of unwanted energy into the same cavities. Bus vent design evolution is discussed for the Solar Dynamics Observatory. Design changes were influenced by a number of factors and concerns, such as contamination control, electrostatic discharge, changes in bus material, and driving fairing ascent pressure for a launch vehicle that was just entering service as this satellite project had gotten underway.

Ultraviolet light attenuation was measured by the Martin Marietta Corporation in 1980 between the wavelengths of approximately 115 nanometers to 300 nanometers. These data are compared to the light attenuation calculated using x-ray interactions with matter, pioneered by the Lawrence Berkley National Laboratories. The Center for X-Ray Optics provides a methodology to calculate light attenuation from x-ray light to 124-nm ultraviolet light. There is a slight overlap in the data, allowing for a comparison of commonly outgassed species from the base materials reported in the Martin Marietta document.

Non-sequential ray tracing for stray light analyses have demonstrated value, but are over-constrained when high sampling and speed are both needed. In cases where real geometry and mechanical surface properties are critical, such analyses are certainly required. But the goal of these analyses is often to attempt to approach the performance that would be achieved if only the optics contributed scatter and only through the sequential optical path. In other words, optical element scatter is the limiting case for system performance. An analysis technique is therefore presented that enables approximate but rapid sequential stray light estimates through deterministic modeling. Results of correlation to nonsequential analyses demonstrate the large range of applicability of this approach. Examples of parametric studies show the value of rapid paraxial estimates for understanding system performance sensitivities.

The generalized Harvey-Shack (GHS) surface scatter theory has been shown to accurately predict the BRDF produced by moderately rough mirror surfaces from surface metrology data. The predicted BRDF also holds for both large incident and scattering angles. Furthermore, it provides good agreement with the classical Rayleigh-Rice theory for those surfaces that satisfy the smooth-surface criterion. The two-dimensional band-limited portion of the surface PSD contributing to scattered radiation is discussed and illustrated for arbitrary incident angles, and the corresponding relevant roughness necessary to calculate the total integrated scatter (TIS) is determined. It is shown that BRDF data measured with a large incident angle can be used to expand the range of surface roughness for which the inverse scattering problem can be solved; i.e., for which the surface PSD can be calculated from measured BRDF data. This PSD and the GHS surface scatter theory can then be used to calculate the BRDF of that surface for arbitrary incident angles and wavelengths that do not satisfy the smooth-surface criterion. Finally, the surface transfer function characterizing both the BTDF and the BRDF of a moderately rough interface separating two media of arbitrary refractive index is derived in preparation for modeling the scattering of structured thin film solar cells.

Ball Aerospace & Technologies Corp. (BATC) developed motion control systems to move the NASA LDCM Operational Land Imager (OLI) relative to the source in the stray light test facility. Stray light tests were performed on both the imaging and calibration apertures over a wide range of illumination angles. Test results will be shown that demonstrate that the stray light performance of both the telescope and the test facility are excellent. Model predictions are also compared to the test results.

In high power laser facilities, the ghost images was usually considered for the spot position and energy density with geometrical optics (GO) but couldn't obtained the ghost images focal spot which was also essential for the ghost images damage threshold. And the energy redistribution on focal spots may induce undesired partial damage as well. Therefore, Collins formula was applying on a single lens to analyze the ghost images focal spot detailed distribution in space. The results were consistent with GO and the output spots on focus were same to Airy spot with different size in different reflection orders.