Results for “Contamination Control Process” — Page 11

NASA NTRS2009

Contamination Examples and Lessons from Low Earth Orbit Experiments and Operational Hardware

Flight experiments flown on the Space Shuttle, the International Space Station, Mir, Skylab, and free flyers such as the Long Duration Exposure Facility, the European Retrievable Carrier, and the EFFU, provide multiple opportunities for the investigation of molecular contamination effects. Retrieved hardware from the Solar Maximum Mission satellite, Mir, and the Hubble Space Telescope has also provided the means gaining insight into contamination processes. Images from the above mentioned hardware show contamination effects due to materials processing, hardware storage, pre-flight cleaning, as well as on-orbit events such as outgassing, mechanical failure of hardware in close proximity, impacts from man-made debris, and changes due to natural environment factors.. Contamination effects include significant changes to thermal and electrical properties of thermal control surfaces, optics, and power systems. Data from several flights has been used to develop a rudimentary estimate of asymptotic values for absorptance changes due to long-term solar exposure (4000-6000 Equivalent Sun Hours) of silicone-based molecular contamination deposits of varying thickness. Recommendations and suggestions for processing changes and constraints based on the on-orbit observed results will be presented.

Pippin, Gary↗

NASA NTRS1984

Environmental control/life support

It is pointed out that the life support systems technology used on projects Mercury, Gemini, Apollo, and Space Shuttle required an employment of expendables. Skylab was the only manned space project which made use of regenerable life support technology, taking into account the employment of a silica gel/molecular sieve for carbon dioxide removal. A number of investigations indicate that significant launch weight and volume as well as recurring cost savings can be realized by using regenerative life support processes for a Space Station. A number of developed regenerative processes are believed to be applicable to a Space Station. Aspects of air revitalization are discussed, taking into account carbon dioxide reduction, oxygen generation, trace contaminant control, temperature and humidity control, instrumentation, and nitrogen supply. Attention is also given to water reclamation, solid waste treatment, and future development and testing programs.

Quattrone, P. D.↗

NASA NTRSDate not supplied

Hydrogen Peroxide as a Method for Bioburden Reduction in Facilities with Strict Materials Requirements.

The cleanrooms used to curate NASA’s Astromaterials samples are carefully monitored for particulate and inorganic contamination. The clean labs also have a very limited set of acceptable materials and cleaning agents to further minimize the potential for contamination. Labs are cleaned primarily with isopropyl alcohol. Astromaterials samples are handled with tools made of stainless steel (304 or 316), Teflon, or aluminum alloy (6061). Although our current collections are not particularly susceptible to biological alteration or organic contamination, this will not be the case for new collections from the OSIRIS-REx mission, Hayabusa2, and from Mars Sample Return. Therefore, it is necessary to develop and test methods to reduce the bioburden in astromaterials cleanrooms without introducing unwanted contaminants. We will report on the results of three case studies where 7.5 wt% hydrogen peroxide was prepared from a stock solution of ultrapure 30 wt% hydrogen peroxide (JT Baker) using curation-grade ultrapure water. We followed CDC (Center for Disease Control) guidelines for using hydrogen peroxide as a high level disinfectant. This solution was used to clean a glovebox prior to processing Apollo samples, as well as surfaces in the Antarctic meteorite processing lab and Stardust lab after facilities monitoring indicated an unwanted increase in bioburden. In all three instances, the culturable bioburden was significantly reduced after a 30 min. exposure to the 7.5% hydrogen peroxide solution without a corresponding increase in inorganic or organic contamination. We observed 77 to 100% reductions in the bioburden recovery rate. In one case study, we also performed amplicon DNA sequencing on samples collected from the surfaces before and after cleaning. We observed a significant change in microbial community composition after peroxide cleaning. These results suggest that routine cleaning with hydrogen peroxide could be an effective way to control bioburden in astromaterials cleanrooms and other facilities with strict contamination control requirements.

A B Regberg↗

NASA NTRSDate not supplied

Hydrogen Peroxide as a Method for Bioburden Reduction in Facilities with Strict Materials Requirements

The cleanrooms used to curate NASA’s Astromaterials samples are carefully monitored for particulate and inorganic contamination. The clean labs also have a very limited set of acceptable materials and cleaning agents to further minimize the potential for contamination. Labs are cleaned primarily with isopropyl alcohol. Astromaterials samples are handled with tools made of stainless steel (304 or 316), Teflon, or aluminum alloy (6061). Although our current collections are not particularly susceptible to biological alteration or organic contamination, this will not be the case for new collections from the OSIRIS-REx mission, Hayabusa2, and from Mars Sample Return. Therefore, it is necessary to develop and test methods to reduce the bioburden in astromaterials cleanrooms without introducing unwanted contaminants. We will report on the results of three case studies where 7.5 wt% hydrogen peroxide was prepared from a stock solution of ultrapure 30 wt% hydrogen peroxide (JT Baker) using curation-grade ultrapure water. We followed CDC (Center for Disease Control) guidelines for using hydrogen peroxide as a high level disinfectant. This solution was used to clean a glovebox prior to processing Apollo samples, as well as surfaces in the Antarctic meteorite processing lab and Stardust lab after facilities monitoring indicated an unwanted increase in bioburden. In all three instances, the culturable bioburden was significantly reduced after a 30 min. exposure to the 7.5% hydrogen peroxide solution without a corresponding increase in inorganic or organic contamination. We observed 77 to 100% reductions in the bioburden recovery rate. In one case study, we also performed amplicon DNA sequencing on samples collected from the surfaces before and after cleaning. We observed a significant change in microbial community composition after peroxide cleaning. These results suggest that routine cleaning with hydrogen peroxide could be an effective way to control bioburden in astromaterials cleanrooms and other facilities with strict contamination control requirements.

A B Regberg↗

NASA NTRS2023

Natural sunlight-driven oxidation of Mn 2+ (aq) and heterogeneous formation of Mn oxides on hematite

The oxidation of dissolved Mn 2+ (aq) plays a critical role in driving manganese cycles and regulating the fate of essential elements and contaminants in environmental systems. Based on sluggish oxidation rate, abiotic processes have been considered less effective oxidation pathway for manganese oxidation in environmental systems. Interestingly, a recent study (Jung et al., 2021) has shown that the rapid photochemical oxidation of Mn 2+ (aq) could be a feasible scenario to uncover the potential significance of abiotic Mn 2+ (aq) oxidation. Nevertheless, the significance of photochemical oxidation of Mn 2+ (aq) under natural sunlight exposure remains unclear. Here, we demonstrate the rapid photocatalytic oxidation of Mn 2+ (aq) and the heterogeneous growth of tunnel-structured Mn oxides under simulated freshwater and seawater conditions in the presence of natural sunlight and hematite. The natural sunlight-driven photocatalytic oxidation of Mn 2+ (aq) by hematite showed kinetic constants of 1.02 h -−1 and 0.342 h −1 under freshwater and seawater conditions, respectively. The natural sunlight-driven photocatalytic oxidation rates are quite comparable to the results obtained from the previous laboratory test using artificial sunlight, which has ∼4.5 times stronger light intensity. It is likely because of ∼5.5 times larger light exposure area in the natural sunlight-driven photocatalytic oxidation than that of the laboratory test using artificial sunlight. We also elucidate the roles of cation species in controlling the oxidation rate of Mn 2+ (aq) and the crystalline structure of Mn oxide products. Specifically, in the presence of large amounts of cations, the oxidation rate of Mn 2+ (aq) was slower likely because of competitive adsorption. Furthermore, our findings highlight that Mn 2+ contributes significantly to the formation of large-tunneled Mn oxides. These results illuminate the importance of abiotic photocatalytic processes in controlling the redox chemistry of Mn in real environmental aqueous systems on the oxidation of Mn 2+ (aq), and provide an environmentally sustainable approach to effectively remediate water contaminated with Mn 2+ (aq) using natural sunlight.

Junyeong Choi↗

NASA NTRS1993

An overview of the on-orbit contamination of the Long Duration Exposure Facility (LDEF)

Contamination that leads to degradation of critical surfaces becomes a vital design issue for many spacecraft programs. One of the processes that must be considered is the on-orbit accumulation of contaminants. The Long Duration Exposure Facility (LDEF) has presented an opportunity to examine the deposits on surfaces returned from orbit in order to help in understanding the deposition processes and the current models used to predict spacecraft contamination levels. The results from various investigators on the contamination of LDEF have implications for material selection, contamination models, and contamination control plans for the design of future spacecraft.

Stuckey, W. K.↗

NASA NTRS2012

Nanoporous Materials in Atmosphere Revitalization

Atmospheric Revitalization (AR) is the term the National Aeronautics and Space Administration (NASA) uses to encompass the engineered systems that maintain a safe, breathable gaseous atmosphere inside a habitable space cabin. An AR subsystem is a key part of the Environmental Control and Life Support (ECLS) system for habitable space cabins. The ultimate goal for AR subsystem designers is to 'close the loop', that is, to capture gaseous human metabolic products, specifically water vapor (H2O) and Carbon dioxide (CO2), for maximal Oxygen (o2) recovery and to make other useful resources from these products. The AR subsystem also removes trace chemical contaminants from the cabin atmosphere to preserve cabin atmospheric quality, provides O2 and may include instrumentation to monitor cabin atmospheric quality. Long duration crewed space exploration missions require advancements in AR process technologies in order to reduce power consumption and mass and to increase reliability compared to those used for shorter duration missions that are typically limited to Low Earth Orbit. For example, current AR subsystems include separate processors and process air flow loops for removing metabolic CO2 and volatile organic tract contaminants (TCs). Physical adsorbents contained in fixed, packed beds are employed in these processors. Still, isolated pockets of high carbon dioxide have been suggested as a trigger for crew headaches and concern persists about future cabin ammonia (NH3) levels as compared with historical flights. Developers are already focused on certain potential advancements. ECLS systems engineers envision improving the AR subsystem by combining the functions of TC control and CO2 removal into a single regenerable process and moving toward structured sorbents - monoliths - instead of granular material. Monoliths present a lower pressure drop and eliminate particle attrition problems that result from bed containment. New materials and configurations offer promise for lowering cabin levels of CO2 and NH3 as well as reducing power requirements and increasing reliability. This chapter summarizes the challenges faced by ECLS system engineers in pursuing these goals, and the promising materials developments that may be part of the technical solution for challenges of crewed space exploration beyond LEO.

Hernandez-Maldonado, J.↗

NASA NTRS2014

Black Molecular Adsorber Coatings for Spaceflight Applications

The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

adsorption↗

NASA NTRS1985

Elimination of directional wave spectrum contamination from noise in elevation measurements

The Surface Contour Radar (SCR) is a 36-GHz computer-controlled airborne radar which generates a false-color-coded elevation map of the sea surface below the aircraft in real time, and can routinely produce ocean directional wave spectra with post-flight data processing which have much higher angular resolution than pitch-and-roll buoys. The SCR range measurements are not error-free and the resulting errors in the elevations corrupt the directional wave spectrum. This paper presents a technique for eliminating that contamination.

Walsh, E. J.↗

NASA NTRS1975

Fused silica reflecting heat shields for outer planet entry probes

The development of slip-cast fused silica is discussed as a heat shield designed to meet the needs of outer-planet entry probes. The distinguishing feature of silica is its ability to reflect the radiation imposed by planetary-entry environments. This reflectivity is particularly sensitive to degradation by the presence of trace amounts of contaminants introduced by the starting materials or by processing. The microstructure of a silica configuration also significantly influences the reflectivity and other thermomechanical properties. The processing techniques attendant on controlling microstructure while maintaining purity are discussed. The selection of a starting material of essential purity precludes the use of purified natural quartz and requires the use of synthetic fused silica. The silica is characterized in a limited combined heating test environment. The surface mass loss is controlled by liquid runoff from a relatively low-temperature melt layer; the reflectance is basically maintained and the material achieves a surprisingly high heat of ablation.

Congdon, W. M.↗

NASA NTRS2014

Black Molecular Adsorber Coatings for Spaceflight Applications

The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

adsorption↗

NASA NTRS2001

Facility Concepts for Mars Returned Sample Handling

Samples returned from Mars must be held in quarantine until their biological safety has been determined. A significant challenge, unique to NASA's needs, is how to contain the samples (to protect the blaspheme) while simultaneously protecting their pristine nature. This paper presents a comparative analysis of several quarantine facility concepts for handling and analyzing these samples. The considerations in this design analysis include: modes of manipulation; capability for destructive as well as non-destructive testing; avoidance of cross-contamination; linear versus recursive processing; and sample storage and retrieval within a closed system. The ability to rigorously contain biologically hazardous materials has been amply demonstrated by facilities that meet the specifications of the Center for Disease Control Biosafety Level 4. The newly defined Planetary Protection Level Alpha must provide comparable containment while assuring that the samples remain pristine; the latter requirement is based on the need to avoid compromising science analyses by instrumentation of the highest possible sensitivity (among other things this will assure that there is no false positive detection of organisms or organic molecules - a situation that would delay or prevent the release of the samples from quarantine). Protection of the samples against contamination by terrestrial organisms and organic molecules makes a considerable impact upon the sample handling facility. The use of glove boxes appears to be impractical because of their tendency to leak and to surges. As a result, a returned sample quarantine facility must consider the use of automation and remote manipulation to carry out the various functions of sample handling and transfer within the system. The problem of maintaining sensitive and bulky instrumentation under the constraints of simultaneous sample containment and contamination protection also places demands on the architectural configuration of the facility that houses it.

Cohen, Marc M.↗

NASA NTRS2022

NASA Engineering and Safety Center Technical Bulletin No. 22-08; Contaminant Reduction in High Purity Hydrazine

Hydrazine and its derivatives are used ubiquitously in liquid propulsion systems. In smaller thruster systems, contaminant build up has historically caused flow decay and consequently performance losses. Many of these contaminants are not controlled by the current revision of MIL-PRF-26536 [1], the High Purity Hydrazine (HPH) procurement specification, yet have been observed to be present in HPH at variable concentration and, often exceed potentially problematic levels for small thrusters. This technical bulletin outlines recent work aimed at identifying appropriate separation processes to remove specific target elemental and carbonaceous contamination in HPH.

Technical Bulletin No. 22-08↗

NASA NTRS2006

Summary of Stirling Convertor Testing at NASA Glenn Research Center

The NASA Glenn Research Center (GRC) has been testing free-piston Stirling convertors for potential use in radioisotope power systems. These convertors tend to be in the 35 to 80 W electric power output range. Tests at GRC have accumulated over 80,000 hr of operation. Test articles have been received from Infinia Corporation of Kennewick, Washington and from Sunpower of Athens, Ohio. Infinia designed and built the developmental Stirling Technology Demonstration Convertors (TDC) in addition to the more advanced Test Bed and Engineering Unit convertors. GRC has eight of the TDC's under test including two that operate in a thermal vacuum environment. Sunpower designed and developed the EE-35 and the Advanced Stirling Convertor (ASC). GRC has six of the EE- 35 s and is preparing for testing multiple ASC s. Free-piston Stirling convertors for radioisotope power systems make use of non-contacting operation that eliminates wear and is suited for long-term operation. Space missions with radioisotope power systems are often considered that extend from three to 14 years. One of the key capabilities of the GRC test facility is the ability to support continuous, unattended operation. Hardware, software, and procedures for preparing the test articles were developed to support these tests. These included the processing of the convertors for minimizing the contaminants in the working fluid, developing a helium charging system for filling and for gas sample analysis, and the development of new control software and a high-speed protection circuit to insure safe, round-the-clock operation. Performance data of Stirling convertors over time is required to demonstrate that a radioisotope power system is capable of providing reliable power for multi-year missions. This paper will discuss the status of Stirling convertor testing at GRC.

Schreiber, Jeffrey G.↗

NASA NTRS2006

Summary of Stirling Convertor Testing at GRC

The NASA Glenn Research Center (GRC) has been testing free-piston Stirling convertors for potential use in radioisotope power systems. These convertors tend to be in the 35 to 80 watt electric power output range. Tests at GRC have accumulated over 80,000 hours of operation. Test articles have been received from Infinia Corporation of Kennewick, WA and from Sunpower of Athens, OH. Infinia designed and built the developmental Stirling Technology Demonstration Convertors (TDC) in addition to the more advanced Test Bed and Engineering Unit convertors. GRC has eight of the TDC's under test including two that operate in a thermal vacuum environment. Sunpower designed and developed the EE- 35 and the Advanced Stirling Convertor (ASC). GRC has six of the EE-35's and is preparing for testing multiple ASC's. Free-piston Stirling convertors for radioisotope power systems make use of non-contacting operation that eliminates wear and is suited for longterm operation. Space missions with radioisotope power systems are often considered that extend from three to 14 years. One of the key capabilities of the GRC test facility is the ability to support continuous, unattended operation. Hardware, software, and procedures for preparing the test articles were developed to support these tests. These included the processing of the convertors for minimizing the contaminants in the working fluid, developing a helium charging system for filling and for gas sample analysis, and the development of new control software and a high-speed protection circuit to insure safe, round-the-clock operation. Performance data of Stirling convertors over time is required to demonstrate that a radioisotope power system is capable of providing reliable power for multi-year missions. This paper will discuss the status of Stirling convertor testing at GRC.

Schreiber, Jeffrey G.↗

NASA NTRS1987

Wafer level reliability for high-performance VLSI design

As very large scale integration architecture requires higher package density, reliability of these devices has approached a critical level. Previous processing techniques allowed a large window for varying reliability. However, as scaling and higher current densities push reliability to its limit, tighter control and instant feedback becomes critical. Several test structures developed to monitor reliability at the wafer level are described. For example, a test structure was developed to monitor metal integrity in seconds as opposed to weeks or months for conventional testing. Another structure monitors mobile ion contamination at critical steps in the process. Thus the reliability jeopardy can be assessed during fabrication preventing defective devices from ever being placed in the field. Most importantly, the reliability can be assessed on each wafer as opposed to an occasional sample.

Root, Bryan J.↗

NASA NTRS1993

Space Shuttle reaction control system thruster metal nitrate removal and characterization

The Space Shuttle hypergolic primary reaction control system (PRCS) thrusters continue to fail-leak or fail-off at a rate of approximately 1.5 per flight, attributed primarily to metal nitrate formation in the nitrogen tetroxide (N2O4) pilot operated valves (POV's). The failures have continued despite ground support equipment (GSE) and subsystem operational improvements. As a result, the Johnson Space Center (JSC) White Sands Test Facility (WSTF) performed a study to characterize the contamination in the N204 valves. This study prompted the development and implementation of a highly successful flushing technique using deionized (DI) water and gaseous nitrogen (GN2) to remove the contamination while minimizing Teflon seat damage. Following flushing a comprehensive acceptance test is performed before the thruster is deemed recovered. Between the time WSTF was certified to process flight thrusters (March 1992) and September 1993, a 68 percent thruster recovery rate was achieved. The contamination flushed from these thrusters was analyzed and has provided insight into the corrosion process, which is reported in this publication. Additionally, the long-term performance of 24 flushed thrusters installed in the WSTF Fleet Leader Shuttle reaction control subsystem (RCS) test articles is being assessed. WSTF continues to flush flight and test article thrusters and compile data to investigate metal nitrate formation characteristics in leaking and nonleaking valves.

Saulsberry, R. L.↗

NASA NTRS1992

Catalytic methods using molecular oxygen for treatment of PMMS and ECLSS waste streams, volume 2

Catalytic oxidation has proven to be an effective addition to the baseline sorption, ion exchange water reclamation technology which will be used on Space Station Freedom (SSF). Low molecular weight, polar organics such as alcohols, aldehydes, ketones, amides, and thiocarbamides which are poorly removed by the baseline multifiltration (MF) technology can be oxidized to carbon dioxide at low temperature (121 C). The catalytic oxidation process by itself can reduce the Total Organic Carbon (TOC) to below 500 ppb for solutions designed to model these waste waters. Individual challenges by selected contaminants have shown only moderate selectivity towards particular organic species. The combined technology is applicable to the more complex waste water generated in the Process Materials Management System (PMMS) and Environmental Control and Life Support System (ECLSS) aboard SSF. During the phase 3 Core Module Integrated Facility (CMIF) water recovery tests at NASA MSFC, real hygiene waste water and humidity condensate were processed to meet potable specifications by the combined technology. A kinetic study of catalytic oxidation demonstrates that the Langmuir-Hinshelwood rate equation for heterogeneous catalysts accurately represent the kinetic behavior. From this relationship, activation energy and rate constants for acetone were determined.

Akse, James R.↗