Ultraviolet radiation effects

Solar ultraviolet testing was not developed which will provide highly accelerated (20 to 50X) exposures that correlate to flight test data. Additional studies are required to develop an exposure methodology which will assure that accelerated testing can be used for qualification of materials and coatings for long duration space flight. Some conclusions are listed: Solar UV radiation is present in all orbital environments; Solar UV does not change in flux with orbital altitude; UV radiation can degrade most coatings and polymeric films; Laboratory UV simulation methodology is needed for accelerated testing to 20 UV solar constants; Simulation of extreme UV (below 200 nm) is needed to evaluate requirements for EUV in solar simulation

Correlation of electrical conductivity and radiation-induced free radical concentration in poly/ethylene terephthalate/ and related compounds

Gamma and ultraviolet radiation effects on electronic properties of polyethylene terephthalate and related compound

Ultraviolet Radiation Effects On Rotifers

The purpose of this investigation was to study ultraviolet radiation effects on rotifers. The rotifer studied was Philodina acuticornis odiosa Milne. Isolation cultures were used to grow the rotifers individually in separate U-plate depressions. The source of ultraviolet radiation consisted of four mercury germicidal lamps used in combination to deliver a uniform flux of 315 uW/cm2 over the sample. Five groups of rotifers, one control and four experimental groups of 96 each, were used. The rotifers used were 2-10 hours of age at the beginning of the experiment. The experimental groups were exposed to uv radiation for 3 minutes, 5 minutes, 7 minutes, 9 minutes. The mean lifetime of each of the control, 3 minutes, 5 minutes, 7 minutes, and 9 minutes irradiated groups was 20.4 days, 19.1 days, 17.1 days, 11.5 days, and 6.3 days respectively. No specific theory, nor the mechanism involved is given to explain these uv radiation effects on rotifers. From the data, it is concluded that some radiation shortens the mean lifetimes of rotifers and that there is a threshold exposure after which the survival of the rotifer changes drastically

In situ electron, proton, and ultraviolet radiation effects on thermal control coatings Final report, 15 Sep. 1965 - 15 Jul. 1968

Electron, proton, and ultraviolet radiation effects on thermal control coating

Fundamental investigation of ultraviolet radiation effects in polymeric film-forming materials

A literature search from 1958 to present was conducted on the effect of ultraviolet radiation on polymeric materials, with particular emphasis on vacuum photolysis, mechanisms of degradation, and energy transfer phenomena. The literature from 1958 to 1968 was searched manually, while the literature from 1968 to present was searched by using a computerized keyword system. The primary objective was to provide the necessary background information for the design of new or modified materials with improved stability to the vacuum-radiation environment of space

Low Earth orbital atomic oxygen and ultraviolet radiation effects on polymers

Because atomic oxygen and solar ultraviolet radiation present in the low earth orbital (LEO) environment can alter the chemistry of polymers resulting in degradation, their effects and mechanisms of degradation must be determined in order to determine the long term durability of polymeric surfaces to be exposed on missions such as Space Station Freedom. The effects of atomic oxygen on polymers which contain protective coatings must also be explored, since unique damage mechanisms can occur in areas where the protective coatings has failed. Mechanisms can be determined by utilizing results from previous LEO missions, by performing ground based LEO simulation tests and analysis, and by carrying out focussed space experiments. A survey is presented of the interactions and possible damage mechanisms for environmental atomic oxygen and UV radiation exposure of polymers commonly used in LEO

Vacuum and ultraviolet radiation effects on binders and pigments for spacecraft thermal control coatings

An evaluation of several silicone resin binders and powdered inorganic pigments for potential use in spacecraft thermal-control paint formulations is presented. The pigments were selected on the basis of a hypothesis relating the heat of formation of a compound to the compound's resistance to ultra-radiation-induced degradation. Reflectance measurements were made in situ to determine degradation rates due to ultraviolet radiation. The tested polydimethylsiloxane resins were not significantly affected by long exposures to ultraviolet radiation. All the pigments, which were dispersed in a polydimethylsiloxane resin, were degraded by ultraviolet radiation as determined by an increase of solar absorptance. For the materials evaluated in this study, no evidence was found to indicate that pigments with high heats of formation were resistant to ultraviolet degradation

Ultraviolet radiation effects on aging hams in high moisture conditions

Hams were aged in two rooms thermostatically controlled at 78°F. with a relative humidity of 80 percent. In one of the rooms a germicidal lamp was installed with the hams placed so that the exposure distance approximated 3, 6, 9 and 12 feet or were shielded entirely from the ultraviolet radiation. There were no significant or definite trends in shrinkage loss among the treatments during the periods of salting, equalizing, smoking and aging. Free fatty acids increased significantly with aging time; however, the FFA content among all treatments did not show a significant difference. The control and shielded hams had significantly more mold growth than those exposed to ultraviolet light rays. The physical appearance of the exposed hams was significantly more oily than the control group even though there was a fat exudate in all treatments as aging time increased. Although there were no significant differences among treatments in fat color within the four exposed groups the color blended from a bright yellow to medium yellow as the exposure distance was lengthened. Flavor of the hams as scored by a laboratory panel rated only fair. The reason for this relatively low score is not definitely known; however, the high moisture conditions may be a possible contributing factor

Investigation of space radiation effects in polymeric film-forming materials

The literature search in the field of ultraviolet radiation effects that was conducted during the previous program, Contract No. NAS1-12549, has been expanded to include the effects of charged particle radiation and high energy electromagnetic radiation. The literature from 1958 to 1969 was searched manually, while the literature from 1969 to present was searched by using a computerized keyword system. The information generated from this search was utilized for the design of an experimental program aimed at the development of materials with improved resistance to the vacuum-radiation environment of space. Preliminary irradiation experiments were performed which indicate that the approaches and criteria employed are very promising and may provide a solution to the challenging problem of polymer stability to combined ultraviolet/high energy radiation

Pilot Awareness and Preventative Measures of Ultraviolet Radiation Effects at Altitude

Ultraviolet radiation exposure to pilots while flying at altitude is an issue that has not been widely distributed to the aviation community. Ultraviolet radiation can have long term effects on pilots, and yet there remains a gap in the practical understanding and the preventative measures that can be taken. The following literature review outlines the potential hazards that pilots face from ultraviolet radiation. The aim of the study was to investigate how UV exposure can affect flight crews at altitude. Armed with this knowledge we need to bring ideas to help produce a greater understanding of the effects UV radiation can have. Further educational tools will need to be disseminated to the aviation community so that a greater awareness is developed. These preventative steps will develop a culture over time which has the potential to change the way we approach our time in a cockpit. Pilots are driven by a mission, and if new parameters are introduced, such as applying sunscreen before flight, we will see long time benefits