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Public reporting burden tor this collection of information is estimated to average 1 hour per response, including the time for reviewing Instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Inflatable structures are being developed for use in space to take advantage of the potential for lower packaging volumes and lighter weights. These structures may consist of thin polymer membranes as well as more robust inflatable, then rigidizable, structural elements. For space applications, it must be shown that the materials can tolerate the orbital environment. This includes the effects of solar radiation and electron/proton radiation on the optical properties and mechanical response of the materials, as well as atomic oxygen effects for possible LEO applications. The highest radiation concern is with the thin-film materials, e.g., the canopy and reflector of an antenna or components of a sun shade or solar sail. All materials used in an inflatable structure need to be capable of tolerating the orbital environment and maintaining properties within the mission requirements.The approach to assessing the effects of space environment on materials begins with consideration of the orbital environment. The solar radiation spectrum is not orbital dependent, but the radiation from electrons and protons varies by orders of magnitude, depending on the particular orbit. The atomic oxygen environment is strongly dependent on altitude and solar activity. Once an orbit has been defined, the atmospheric models are available to calculate the flux and energy of the particle radiation. The orbital lifetime then is used to calculate dose levels and solar exposures that the materials must tolerate. With the environment specified, the expected dose in the materials can then be calculated. If damage thresholds are available for the particular materials involved, possible degradation can be predicted; if not, a ground or orbital test is needed. For a ground test to assess the durability of a material in orbit, the methodology is to predict the dose levels in the materials, which then drive the test parameters.The orbital environment of solar, electron and proton radiation are discussed. Typical levels for a LEO, MEO, and GEO orbit are presented, and examples of test conditions to simulate the space environment in a ground test on materials properties are discussed. Available results on materials for inflatables are presented.

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Acrolein can function under a variety of conditions as an effective hydrogen sulfide scavenger in oilfield waterflood systems. The scavenging ability is maximized in waters having a pH range of 6 through 8, a total dissolved solids level below 1 %, and temperatures less than 149°F [65°C].At least 4 ppm acrolein is necessary to achieve sufficient reaction of each original 1 ppm hydrogen sulfide. This reaction req~ires about 2to 20 minutes, depending on the natQre of the system. Although' sand, garnet, or diatornacequs earth filters do not affect the scavenging ability of acrolein, charcoal fIlters, large tanks, long pipelines, higb~temperature WepJ.cos, and rebbilers can produce diwillished effects. Further diminished effects also can be produced when incQpJ.patible chemicals are used concurrently with acrolein. Some application techniques that can lessen or eliminate these adverse conditions I;lre presented. IntroductiOI}Hydrogen sulfide has beed both a corrosive and a toxic nuisancl! to oilfield operations for decades. Although an abundance of literature describing the abatement of hydrogen sulfide in gas and drilling mud systems is ~vailable, these techniques and environments do not appear to have significant utility in oilfield waterflood operations. Related industries-such as the geothermal, the plllp and paper, and the was!ewater j.ndustries-appear to rely on aeration, 1,2 bacteria, 3,4 chemi~al scavengers, 5-7 me~lic salt and oxide beds,8-15 and oxidizers. 16'21 ~though some of these methods are applicable to oilfield waterftood operations, the majority appear impractical befause of cost and compatibility considerations.SpeCific oilfield waterflood operations ~ave used mechabical and chemical technofqgies in an attempt to reQlove hydrogen sulfide from native waters. Some me-chjPrical methods involve aeration, anion exchange resins, degassing, dis~illation, steam reform~ng, and zeolite spfteners. 22 ,23 Most of these methods are viewed currently as being expensive or impractical.

The exterior optical surfaces of satellites are directly exposed to the harsh space environment. Here, a multilayer dielectric solar rejection filter was deposited on a silicon substrate and then subjected to electron and proton irradiation, simulating an orbital environment. Following the exposure, damage was observed that was attributed to dielectric breakdown. Optical and scanning electron microscopy revealed extensive pitting as a result of this exposure. The typical size of discharge pits was 50-100 microns at the surface, extending to the substrate material, where a 10 micron diameter melt region was found. Pit damage occurred at pre-existing coating defects and was accelerated by preexposure to proton radiation. Pitting was not observed on similar samples that had also been overcoated with a conductive thin-film.