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At least 235 records · Page 13

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NASA NTRS2011

Assessment of Gamma Radiation Resistance of Spores Isolated from the Spacecraft Assembly Facility During MSL Assembly

Spore forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate extreme environmental conditions such as radiation, desiccation, and high temperatures. Since the Viking era (early 1970's), spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. There is a growing concern that desiccation and extreme radiation resistant spore forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequently proliferate on another solar body. Such forward contamination would certainly jeopardize future life detection or sample return technologies. It is important to recognize that different classes of organisms are critical while calculating the probability of contamination, and methods must be devised to estimate their abundances. Microorganisms can be categorized based on radiation sensitivity as Type A, B, C, and D. Type C represents spores resistant to radiation (10% or greater survival above 0.8 mRad gamma radiation). To address these questions we have purified 96 spore formers, isolated during planetary protection efforts of Mars Science Laboratory assembly for gamma radiation resistance. The spores purified and stored will be used to generate data that can be used further to model and predict the probability of forward contamination.

extreme environments↗

NASA NTRS2012

External Surface Changes Observed on the International Space Station (ISS) Through 2012

As the International Space Station (ISS) surpasses 13 years of on-orbit operation, 11 of those years continuously inhabited, external surfaces of the vehicle have shown a wide variety of visible environmental effects. Throughout, the ISS program has maintained a significant effort to routinely document the vehicle external surface condition and to monitor those changes with time. The impacts of micrometeoroids and orbital debris, surface changes from molecular contamination of various sources, and the effects of ultraviolet radiation and atomic oxygen have all been noted. The tremendous size and complexity of the ISS vehicle has yielded a wide variety of observations of interest to the spacecraft materials engineer concerning long-term, low earth orbit (LEO) space environmental effects (SEE). In addition, inadvertent materials substitutions have been identified because of these environmental effects, as well as inadequate contamination control practices likely occurring during hardware manufacture and assembly. Some of the observations from our photography are purely artifacts of the unusual lighting conditions and environments that exist in space. A compilation of ISS on-orbit photography representing all of these aspects is presented, demonstrating the various SEE and their impacts as a function of time in LEO, including interpretations of those effects.

Golden, Johnny L.↗

DOE OSTI2021

National Emission Standards for Hazardous Air Pollutants – Radionuclide Emissions Calendar Year 2020

The U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Field Office (NNSA/NFO) operates the Nevada National Security Site (NNSS) and the North Las Vegas Facility (NLVF). From 1951 through 1992, the NNSS was the continental testing location for U.S. nuclear weapons. Radionuclides in air from NNSS activities have been monitored since the initiation of atmospheric testing. After 1962, testing was limited to underground detonations, which greatly reduced radiation exposure to the public. Since the end of nuclear testing in 1992, radiation monitoring has focused on detecting airborne radionuclides from historically contaminated soils because this sources dominates the potential offsite dose. These radionuclides are derived from re-suspension of soil (primarily by wind) and emission of tritium-contaminated soil moisture through evapotranspiration. Low amounts of legacy-related tritium are also emitted to air at the NLVF, an NNSS support complex in North Las Vegas. To protect the public from harmful levels of manmade radiation, the Clean Air Act, National Emission Standards for Hazardous Air Pollutants (NESHAP), specifically the National Emission Standards for Emissions of Radionuclides Other Than Radon From Department of Energy Facilities (40 CFR 61, Subpart H, 2020) limits the release of radioactivity from a DOE facility to that which would cause 10 millirem per year (mrem/y) effective dose equivalent (EDE) to any member of the public. This limit does not include radiation unrelated to NNSS activities. Unrelated doses could come from naturally occurring radioactive elements, from sources such as medically or commercially used radionuclides, or from sources outside of the United States, such as Japan’s Fukushima nuclear power plant, which was damaged in 2011. NNSA/NFO demonstrates compliance with the NESHAP limit by reporting environmental measurements of radionuclide air concentrations at critical receptor locations on the NNSS. This alternative was proposed and formerly submitted to the U.S. Environmental Protection Agency (EPA) in 2001 (EPA 2001a) and has been the method used to demonstrate compliance with the 40 CFR 61.92 dose standard since 2005. Six locations on the NNSS have been established to act as critical receptor locations to demonstrate compliance with the NESHAP limit. These locations are closer to radionuclide releases than where the public resides so they act as protective substitutes for public receptor locations. Compliance is demonstrated if the measured annual average concentration is less than the NESHAP Concentration Level (CL) for Environmental Compliance listed in Table 2 of 40 CFR 61, Appendix E. For multiple radionuclides, compliance is demonstrated when the sum of the fractions (determined by dividing each radionuclide’s concentration by its CL and then adding the fractions together) is less than 1.0. The EPAapproved air transport model, called the Clean Air Package 1988 (CAP88-PC) is also used to calculate the effective dose equivalent to the maximally exposed individual from NNSS air emissions. CAP88-PC was also used to calculate the population dose, or the collective EDE (expressed as person-rem [roentgen equivalent man] per year [person-rem/y]) for all individuals combined who reside within 80 kilometers (km) of NNSS emission sources. In 2020, the potential dose from radiological emissions to air from both current and past NNSS activities was well below the 10 mrem/y dose limit. This is demonstrated by both the air sampling data collected at critical receptor air monitoring stations and CAP88-PC modeling. The average concentrations of radioactivity at air critical receptor stations ranged from 0.2% to a maximum of 4.2% of the allowed NESHAP limit. CAP88-PC modeling of all 2020 NNSS radionuclide emissions showed the maximally exposed individual to be in Amargosa Valley and this individual received a potential dose of 0.063 mrem/y. The collective dose was calculated to be 0.29 person-rem/year for the 521,300 people who lived within 80 km of NNSS emission sources.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2020

NTS-SS-SNL-NMSITE-2017-0004,"Contamination Monitor Left in Service After Inadequate Calibration" Causes Not Fully Addressed (ES&H Causal Analysis Report)

Sandia National Laboratories Radiation Protection department did not successfully address the causes leading to the issue NTS-SS-SNL-NMSITE-2017-0004, “Contamination Monitor Left in Service After Inadequate Calibration”, nor identify through the verification and validation process that corrective actions were not fully implemented and effective at addressing the issue(s). This report is the third causal in four years associated with the iPCM12 instrument and the Radiation Protection Instrumentation (RPI) organization within Radiation Protection (00628).

61 RADIATION PROTECTION AND DOSIMETRY↗

NASA NTRS1972

Fundamentals of spacecraft thermal design.

The papers deal with and are grouped according to four major issues. These are: surface radiation properties, including synthesis and measurement, space flight effect, and contamination effects; thermal analysis, including reentry vehicle analysis, radiant heat transfer between surfaces, and thermal contact conductance of surfaces; heat pipes, including possible applications, operating characteristics, and design, fabrication and testing of heat pipes; and thermal design, including radiative, ablative, and active cooling thermal protection of the leading edge of a space-shuttle wing, and space station environmental thermal control. Individual items were previously announced in issues 06 and 11, 1971.

Lucas, J. W.↗

NASA NTRS2016

Capabilities of the Environmental Effects Branch at Marshall Space Flight Cente

The Environmental Effects Branch at the Marshall Space Flight Center supports a myriad array of programs for NASA, DoD, and commercial space including human exploration, advanced space propulsion, improving life on Earth, and the study of the Sun, the Earth, and the solar system. The branch provides testing, evaluation, and qualification of materials for use on external spacecraft surfaces and in contamination-sensitive systems. Space environment capabilities include charged particle radiation, ultraviolet radiation, atomic oxygen, impact, plasma, and thermal vacuum, anchored by flight experiments and analysis of returned space hardware. These environmental components can be combined for solar wind or planetary surface environment studies or to evaluate synergistic effects. The Impact Testing Facility allows simulation of impacts ranging from sand and rain to micrometeoroids and orbital debris in order to evaluate materials and components for flight and ground-based systems. The Contamination Control Team is involved in the evaluation of environmentally-friendly replacements for HCFC-225 for use in propulsion oxygen systems, developing cleaning methods for additively manufactured hardware, and reducing risk for the Space Launch System.

Rogers, Jan↗

NASA NTRS1981

Auroral X-ray detection from rocket overflights

Remote sensing of auroral X-rays from the topside can provide both local and global information concerning X-ray and energetic particle deposition within the middle atmosphere. Usually, contamination of X-ray detectors by corpuscular radiation can severely affect the scope and accuracy of the measurement. Preliminary results obtained with a rocket-borne instrument designed to operate cleanly in a precipitating particle environment are reported. Two dimensional images of the atmospheric bremsstrahlung X-ray sources were also constructed from the detector scan produced by payload translation and coning.

Goldberg, A.↗

NASA NTRS1982

Mapping of auroral X-rays from rocket overflights

Remote sensing of energetic auroral X-rays from above the emission region can provide both local and global information regarding X ray and energetic electron deposition within the middle atmosphere. However, contamination of X ray detectors by local corpuscular radiation can severely affect the scope and accuracy of the detector measurements. It is, therefore, necessary to employ techniques designed to observe X rays while rejecting the far more intense corpuscular radiation component. A suitable approach for the mapping of auroral X rays involves the employment of rockets for flights above the emission region. A description is presented of the results obtained from two rocket flights launched from Poker Flat Research Range, Alaska, during aurorally active periods in March 1978. The data were measured with the aid of scanning detectors protected from particles by broom magnet techniques.

Goldberg, R. A.↗

NASA NTRS1987

Degradation Of Reflectors And Dielectrics

Report describes important degrading effects of atmosphere and outer-space environments on reflective surfaces and dielectrics. For reflective surfaces, terrestrial effects include soiling on glass surfaces and changing with time. Space effects include ultraviolet enhancement of contamination and possible surface erosion due to solar radiation, impact of debris, and interactions with atomic oxygen. Dielectrics similarly affected in both environments.

Bouquet, Frank L.↗

NASA NTRS1990

Scientific guidelines for preservation of samples collected from Mars

The maximum scientific value of Martian geologic and atmospheric samples is retained when the samples are preserved in the conditions that applied prior to their collection. Any sample degradation equates to loss of information. Based on detailed review of pertinent scientific literature, and advice from experts in planetary sample analysis, number values are recommended for key parameters in the environmental control of collected samples with respect to material contamination, temperature, head-space gas pressure, ionizing radiation, magnetic fields, and acceleration/shock. Parametric values recommended for the most sensitive geologic samples should also be adequate to preserve any biogenic compounds or exobiological relics.

Gooding, James L.↗

NASA NTRS1992

Surface analysis of anodized aluminum clamps from NASA-LDEF satellite

Surface analysis results of selected anodized aluminum clamps containing black (Z306) and white (A276) paints which received nearly six years of Low Earth Orbit (LEO) exposure on the Long Duration Exposure Facility are reported. Surface analytical techniques, including x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and scanning electron microscopy/energy dispersive analysis by x-ray (SEM/EDAX), showed significant differences in the surface composition of these materials depending upon the position on the LDEF. Differences in the surface composition are attributed to varying amounts of atomic oxygen and vacuum ultraviolet radiation (VUV). Silicon containing compounds were the primary contaminant detected on the materials.

Grammer, H. L.↗

NASA NTRS1992

The possible effects of the natural and induced space environment on the optical and thermal properties of EOS surfaces

Space missions, including that of EOS (Earth Observing System), will continue to be subjected to both the natural and induced space environment. The concerns associated with this fact will not go away. The NASA and DoD have recognized the need for long-life stability of materials and structures to the space environment. The major areas of interest include: thermal cycling, UV degradation, space radiation exposure, orbital debris, atomic oxygen erosion, and contamination control. Having flown a number of space environmental effects monitors, SAIC has developed both a data base to understand the magnitude of this problem and mitigation techniques to reduce the impact.

Maag, Carl R.↗

NASA NTRS1994

Investigation of a laboratory candidate for the carrier of the 4430 A diffuse interstellar band

The 4430 A diffuse interstellar band (DIB) is unique among DIB's in that as one of the strong bands, it is the bluest strong band with no others observed at shorter wavelengths. This position at the edge of the DIF 'forrest' suggests it may be the easiest to replicate in the laboratory. In earlier experiments (Wdowiak 1980) an interesting candidate using a gas discharge followed by cryogenic matrix isolation was produced, and this report details its further investigation. This absorption feature, produced when 1 part CH4 in 200 parts Ar is discharged and frozen out approximately 10 K, is at a wavelength of 4500 A in the argon matrix. Our recent experiments strongly indicate it is due to a carbon-based reactive species that is stable against mercury vapor UV radiation, and not likely to be from a contaminant. The effect of matrix shift can be estimated by considering the blueward shift between Ar and Ne matrices in the cases of the pyrene and C60 cations. This suggests that a shift from 4500 A for an Af matrix to the vicinity of 4300 A for a Ne matrix and the gas phase is not unreasonable. A liquid He cooled Ne matrix isolation experiment was prepared to determine the wavelength of the feature in that matrix. Replacing CH4 with C2H2 results in an equivalent absorption due to C3, greatly diminished absorptions from C2 and Ch, and no observable feature at 4500 A. To date our experiments indicate CH4 is a favored precursor for production of the reactive carrier of the 4500 A feature. Perhaps C2H2 is not suitable because of its tendency to polymerize easily in the discharge.

Wdowiak, Thomas J.↗

NASA NTRS1995

Solid film lubricants and thermal control coatings flown aboard the EOIM-3 MDA sub-experiment

Additional experimental data were desired to support the selection of candidate thermal control coatings and solid film lubricants for the McDonnell Douglas Aerospace (MDA) Space Station hardware. The third Evaluation of Oxygen Interactions With Materials Mission (EOIM-3) flight experiment presented an opportunity to study the effects of the low Earth orbit environment on thermal control coatings and solid film lubricants. MDA provided five solid film lubricants and two anodic thermal control coatings for EOIM-3. The lubricant sample set consisted of three solid film lubricants with organic binders one solid film lubricant with an inorganic binder, and one solid film lubricant with no binder. The anodize coating sample set consisted of undyed sulfuric acid anodize and cobalt sulfide dyed sulfuric acid anodize, each on two different substrate aluminum alloys. The organic and inorganic binders in the solid film lubricants experienced erosion, and the lubricating pigments experienced oxidation. MDA is continuing to assess the effect of exposure to the low Earth orbit environment on the life and friction properties of the lubricants. Results to date support the design practice of shielding solid film lubricants from the low Earth orbit environment. Post-flight optical property analysis of the anodized specimens indicated that there were limited contamination effects and some atomic oxygen and ultraviolet radiation effects. These effects appeared to be within the values predicted by simulated ground testing and analysis of these materials, and they were different for each coating and substrate.

Murphy, Taylor J.↗

NASA NTRS1975

A study of molecular contamination

Contamination kinetics of typical space materials were studied using several techniques, including ellipsometry. Data were obtained on contaminant deposition rates, sticking coefficients, and reevaporation of the contamination. Materials studied included silicone sealants, a thermal control paint, and a graphite laminate as contaminant sources, and gold coated surfaces, a thermal control paint and a second surface mirror material as the contaminees. Both deposition and reevaporation rates were found to be nonlinear with time, and followed an exponential decay. A hypothesis is presented that the nonlinear behavior was a result of disproportionation of the molecular weight fractions of the polymers. The measured sticking coefficients were found to vary substantially with temperature over narrow ranges. Simulated space radiation was found to reduce the evaporation rates of contaminants by several orders of magnitude.

Allen, T. H.↗

NASA NTRS1992

Z306 molecular contamination ad hoc committee results

LDEF external surfaces which did not receive significant amounts of atomic oxygen were observed to be coated with a brown contamination, apparently the result of a condensed organic residue darkened due to UV radiation exposure. During the initial Materials Special Investigation Group (MSIG) Meeting after LDEF deintegration, held in Seattle - July 1990, this organic contamination was the subject of much discussion. The amount of contamination was thought to be significant and its source was immediately believed to be the Z306 black thermal control coating used to coat the entire inner surface of LDEF. Due to the size of the structure, it was not feasible to bake-out the coating. However, initial data on the contamination film was confusing in that significant amounts of silicon was observed by several different researchers. Silicon (from silicone) was not expected to be a potential outgassing product of the Z306 polyurethane coating. To investigate the connection between external contamination and the interior paint, a MSIG ad hoc committee was formed.

Golden, Johnny L.↗

DOE OSTI2020

Lessons Learned from Demolition of Hanford's Plutonium Finishing Plant - 20507

U.S. Department of Energy (DOE) contractor CH2M Hill Plateau Remediation Company (CHPRC), a Jacobs owned company, is making significant progress demolishing the Plutonium Finishing Plant (PFP), which has long been known as one of the most hazardous buildings in the DOE Environmental Management Complex (DOE Complex). The facility is located on the Hanford Site and produced plutonium metal during the Cold War. Production was stopped in 1989, the facility was formally shut down in 1996, and material processing was completed in 2004. After approximately 25 years of demolition preparations, open-air demolition of the main portions of the Hazard Category II nuclear facility began in November 2016. To prepare the PFP for demolition, CHPRC employees performed some of the most hazardous work across the DOE Complex. In addition to extensive demolition preparations, including a wide-reaching communication strategy across the Hanford Site, CHPRC implemented robust controls and monitoring during demolition, and when necessary, adjusted demolition practices and sequence to maintain employee safety and project efficiency. Demolition of the main PFP building began in November 2016. The technical complexity, high hazards and radiological concerns have all led to a difficult demolition environment. Following a spread of contamination at the project site beyond the radiological boundaries in December 2017, work was halted and a recovery plan was generated to allow the demolition work to continue. After the implementation of additional controls and concurrence from regulatory agencies and DOE, the demolition was ready to resume work and reinitiated in August 2018. There are a number of lessons learned from the demolition activities and recovery plan process. This paper allows CHPRC and DoE's Richland Operations Office (RL) to share lessons learned and progress to date with other challenging and hazardous projects across the DOE Complex. Understanding the risk acceptance level is critical to execution of any open-air demolition project and is unique to each facility. Four key lessons learned from this project include: 1) plan execution issues, 2) stakeholder communication issues, 3) watching for summit fever and 4) minimizing exposed contaminated surfaces during demolition. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS2024

Analyses of the MISSE 9-15 Polymers and Composites Experiment 1-4 (PCE 1-4) Contamination Samples

Spacecraft in low Earth orbit (LEO) are subjected to harsh environmental conditions, including radiation (cosmic rays, ultraviolet (UV), x-ray and charged particle radiation), micrometeoroids and orbital debris, temperature extremes, thermal cycling, and atomic oxygen (AO). These environmental exposures can result in erosion, embrittlement and optical property degradation of susceptible materials threatening spacecraft performance and durability. To increase our understanding of environmental effects such as AO erosion and radiation induced embrittlement of spacecraft materials, NASA Glenn Research Center developed a series of experiments that were flown as part of the Materials International Space Station Experiment (MISSE) missions on the exterior of the International Space Station (ISS). Recently, four Glenn experiments with 365 flight samples were flown on ISS’s MISSE-Flight Facility (MISSE-FF). These experiments are the Polymers and Composites Experiment-1 (PCE-1) flown as part of the MISSE-9 mission, the PCE-2 flown as part of the MISSE-10 mission, the PCE-3 flown as part of the MISSE-12 and MISSE-15 missions, and the PCE-4 flown as part of the MISSE-13 mission. Each of these experiments included passive contamination witness samples in each flight direction for post-flight molecular contamination analyses. A total of 13 contamination flight samples were flown. The post-flight analyses of the PCE 1-4 contamination samples include X-ray Photoelectron Spectroscopy (XPS) analyses (surface and ion sputter depth analyses) and optical properties (total reflectance, total transmittance and solar absorptance). This paper provides results of post-flight analyses of the PCE 1-4 contamination samples and their corresponding control samples. Knowledge of on-orbit contamination is important for the PCE 1-4 flight data interpretation.

Atomic Oxygen↗