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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

A Survey of ISS and Visiting Vehicle Returned Surfaces for Environmental Characterization and Computer Model Development

The Orbital Debris Engineering Model (ORDEM) developed by the NASA Orbital Debris Program Office (ODPO) is a data-driven model — extensive radar, optical, laboratory, and in situ measurement data sets have been used to build the model since its earliest versions. A salient aspect of professional software development is the verification and validation (V&V) process. Verification answers the question “Is the model built correctly?” while validation addresses the question “Did we build the correct model?” Less extensive, reserved, or independent data sets serve the validation requirement. Due to the dynamic nature of the orbital debris environment, it is critical to use contemporaneous data sources that represent the current environment to support ORDEM development and validation. ORDEM has utilized in situ data collected from Space Shuttle and Hubble Space Telescope surface inspections, now over a decade old. This historical dataset is fundamental for providing baseline in situ measurement data for sizes between 10 to 300 microns, but new data sources are being evaluated using returned surfaces from or near the International Space Station (ISS). This paper reviews a general microscopic survey of ISS soft goods, the Pressurized Mating Adapter 2 (PMA-2) blanket, and a limited-scope feasibility study conducted on the Space Exploration Technologies Corporation (SpaceX) Dragon capsule’s Thermal Protection System (TPS) material. The PMA-2 blanket, exposed to the space environment between 09 July 2013 and 25 February 2015, is an approximately 3.7 m2-area blanket composed of a betacloth outer layer and multiple ballistic fabric inner layers. The SpaceX Cargo Dragon capsule regularly visited the ISS from 2012 through 2020 and potentially provides a timely and well-characterized source of data for modeling purposes. The capsule’s lateral surfaces use SpaceX Proprietary Ablative Material (SPAM) TPS material, a syntactic foam, for thermal management during all mission phases. Seven SPAM extracted samples have been analyzed to date. This paper will provide an overview of the characterization completed for impact features by size, depth, impactor diameter, and the impactor residues chemical analyses, allowing a differentiation between micrometeoroids and orbital debris and a categorization by mass density and density class. Impactor diameter is estimated using damage equations generated from ground-based hypervelocity impact testing. The orbital debris impactors are compared to the current ORDEM 3.2 model of the environment at ISS altitudes. We briefly discuss the meteoroid impactors, including constituents and mass densities, in the general context of current models.

Phillip Anz-meador↗
NASA NTRSDate not supplied

A Survey of ISS and Visiting Vehicle Returned Surfaces for Environmental Characterization and Computer Model Development

The Orbital Debris Engineering Model (ORDEM) developed by the NASA Orbital Debris Program Office (ODPO) is a data-driven model — extensive radar, optical, laboratory, and in situ measurement data sets have been used to build the model since its earliest versions. A salient aspect of professional software development is the verification and validation (V&V) process. Verification answers the question “Is the model built correctly?” while validation addresses the question “Did we build the correct model?” Less extensive, reserved, or independent data sets serve the validation requirement. Due to the dynamic nature of the orbital debris environment, it is critical to use contemporaneous data sources that represent the current environment to support ORDEM development and validation. ORDEM has utilized in situ data collected from Space Shuttle and Hubble Space Telescope surface inspections, now over a decade old. This historical dataset is fundamental for providing baseline in situ measurement data for sizes between 10 to 300 microns, but new data sources are being evaluated using returned surfaces from or near the International Space Station (ISS). This paper reviews a general microscopic survey of ISS soft goods, the Pressurized Mating Adapter 2 (PMA-2) blanket, and a limited-scope feasibility study conducted on the Space Exploration Technologies Corporation (SpaceX) Dragon capsule’s Thermal Protection System (TPS) material. The PMA-2 blanket, exposed to the space environment between 09 July 2013 and 25 February 2015, is an approximately 3.7 m2-area blanket composed of a betacloth outer layer and multiple ballistic fabric inner layers. The SpaceX Cargo Dragon capsule regularly visited the ISS from 2012 through 2020 and potentially provides a timely and well-characterized source of data for modeling purposes. The capsule’s lateral surfaces use SpaceX Proprietary Ablative Material (SPAM) TPS material, a syntactic foam, for thermal management during all mission phases. Seven SPAM extracted samples have been analyzed to date. This paper will provide an overview of the characterization completed for impact features by size, depth, impactor diameter, and the impactor residues chemical analyses, allowing a differentiation between micrometeoroids and orbital debris and a categorization by mass density and density class. Impactor diameter is estimated using damage equations generated from ground-based hypervelocity impact testing. The orbital debris impactors are compared to the current ORDEM 3.2 model of the environment at ISS altitudes. We briefly discuss the meteoroid impactors, including constituents and mass densities, in the general context of current models.

Phillip Anz-Meador↗
NASA NTRS1992

The role of under-determined approximations in engineering and science application

There is currently a great deal of interest in using response surfaces in the optimization of aircraft performance. The objective function and/or constraint equations involved in these optimization problems may come from numerous disciplines such as structures, aerodynamics, environmental engineering, etc. In each of these disciplines, the mathematical complexity of the governing equations usually dictates that numerical results be obtained from large computer programs such as a finite element method program. Thus, when performing optimization studies, response surfaces are a convenient way of transferring information from the various disciplines to the optimization algorithm as opposed to bringing all the sundry computer programs together in a massive computer code. Response surfaces offer another advantage in the optimization of aircraft structures. A characteristic of these types of optimization problems is that evaluation of the objective function and response equations (referred to as a functional evaluation) can be very expensive in a computational sense. Because of the computational expense in obtaining functional evaluations, the present study was undertaken to investigate under-determinined approximations. An under-determined approximation is one in which there are fewer training pairs (pieces of information about a function) than there are undetermined parameters (coefficients or weights) associated with the approximation. Both polynomial approximations and neural net approximations were examined. Three main example problems were investigated: (1) a function of one design variable was considered; (2) a function of two design variables was considered; and (3) a 35 bar truss with 4 design variables was considered.

Carpenter, William C.↗
NASA NTRS2001

Environmental Barrier Coatings for Silicon-Based Ceramics

Silicon-based ceramics, such as SiC fiber-reinforced SiC (SiC/SiC ceramic matrix composites (CMC) and monolithic silicon nitride (Si3N4), are prime candidates for hot section structural components of next generation gas turbine engines. Silicon-based ceramics, however, suffer from rapid surface recession in combustion environments due to volatilization of the silica scale via reaction with water vapor, a major product of combustion. Therefore, application of silicon-based ceramic components in the hot section of advanced gas turbine engines requires development of a reliable method to protect the ceramic from environmental attack. An external environmental barrier coating (EBC) is considered a logical approach to achieve protection and CP long-term stability. The first generation EBC consisted of two layers, mullite (3Al2O3-2SiO2) bond coat and yttria-stabilized zirconia (YSZ, ZrO2-8 Wt.% Y2O3) top coat. Second generation EBCs, with substantially improved performance compared with the first generation EBC, were developed in the NASA High Speed Research-Enabling Propulsion Materials (HSR-EPM) Program. The first generation EBC consisted of two layers, mullite (3Al2O3-2SiO2) bond coat and yttria-stabilized zirconia (YSZ, ZrO2-8 wt.% Y2O3) top coat. Second generation EBCs, with substantially improved performance compared with the first generation EBC, were developed in the NASA High Speed Research-Enabling Propulsion Materials (HSR-EPM) Program (5). They consist of three layers, a silicon first bond coat, a mullite or a mullite + BSAS (BaO(1-x)-SrO(x)-Al2O3-2SiO2) second bond coat, and a BSAS top coat. The EPM EBCs were applied on SiC/SiC CMC combustor liners in three Solar Turbines (San Diego, CA) Centaur 50s gas turbine engines. The combined operation of the three engines has accumulated over 24,000 hours without failure (approximately 1,250 C maximum combustor liner temperature), with the engine in Texaco, Bakersfield, CA, accumulating about 14,000 hours. As the commercialization of Si-based ceramic components in gas turbines is on the horizon, a major emphasis is placed on EBCs for two reasons. First, they are absolute necessity for the protection of Si-based ceramics from water vapor. Second, they can enable a major enhancement in the performance of gas turbines by creating temperature gradients with the incorporation of a low thermal conductivity layer. Thorough understanding of current state-of-the-art EBCs will provide the foundation upon which development of future EBCs will be based. Phase stability and thermal conductivity of EPM EBCs are published elsewhere. This paper will discuss the chemical/environmental durability and silica volatility of EPM EBCs and their impact on the coating's upper temperature limit.

Lee, Kang N.↗
DOE OSTI2023

Interphasial engineering for Ni-rich NMC cathode materials

Ni-rich LiNi 1-x-y Mn x CoyO 2 , (NMC: 1-x-y ≥ 0.6) are promising cathode materials for lithium-ion batteries (LIBs) due to high reversible capacity and low cost. However, the fast capacity decay and voltage fading caused by interphasial instability requires improvement. The unstable cathodeelectrolyte interphase (CEI) and transition metal (TM) dissolution at higher voltages can lead to the drastic deterioration of electrochemical performance. In this review, recent approaches to novel electrolyte and additive design, cathode engineering including artificial CEI, and doping/coating on the surface of particles or the whole electrode are comprehensively summarized. In conclusion, the importance of multi-model and multi-scale characterization methods in understanding the effects of interphasial chemistry on battery performance is highlighted.

25 ENERGY STORAGE↗
DOE OSTI2020

Identification of highly active surface iron sites on Ni(OOH) for the oxygen evolution reaction by atomic layer deposition

Atomic layer deposition (ALD) has become a versatile tool in catalysis, allowing for precise synthesis of catalysts useful for gaining fundamental understanding of complex systems. In this work, ALD was used to perform surface-directed modification of Ni(OH) 2 /Ni(OOH) electrocatalysts for the oxygen evolution reaction (OER) to elucidate the different roles of iron as a surface dopant and as iron distributed throughout the NiOOH structure. Electrochemical and material characterization of FeO x ALD-modified Ni(OH) 2 indicates that iron is deposited on the surface of Ni(OH) 2 sheets without modifying its bulk properties. Sub-monolayer amounts of iron were deposited on the surface of Ni(OH) 2 using low cycle numbers of ALD. This surface iron results in high OER activity, characteristic of Ni-Fe(OOH) catalysts. Ni(OH) 2 /Ni(OOH) catalysts modified to incorporate iron throughout the structure were prepared by depositing large cycle numbers of FeO x ALD, which results in the deposition of a Fe 2 O 3 overlayer. Corrosion of this Fe 2 O 3 overlayer during electrochemical cycling in alkaline electrolyte leads to the incorporation of iron throughout the structure of Ni(OH) 2 /Ni(OOH) while leaving some Fe at the surface. Incorporation of iron throughout the Ni(OH) 2 /Ni(OOH) structure was found to increase OER geometric activity for thick, high surface area Ni(OH) 2 /Ni(OOH) catalysts. Lastly, NiFeO x electrocatalysts synthesized fully by ALD were investigated for the OER; these catalysts demonstrated high OER activity and potential for photocatalysis applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1998

Preliminary Tuft Testing of Metallic Bristles Versus PS212, PS300, and HVOF300

Turbine engine brush seals are designed with sacrificial brushes and hard shaft coatings to minimize shaft wear and reduce the cost of engine overhauls. Replacing a worm seal is more cost and time effective than refinishing an engine shaft. However, this tribological design causes excessive brush wear and reduces long term seal efficiency. An alternative approach is to coat the shaft with a solid lubricant and allow the bristles to wear into the shaft coating similar to traditional abradable labyrinth seals. This approach can result in reduced seal leakage by forcing the leakage to flow through the seal bristle pack or through a more tortuous shaft wear track. Key to this approach is limiting the shaft wear to an acceptable level were surface refinishing would not be required during every engine overhaul. Included in this paper are brush seal tuft test results for four metallic bristles (nickel-chrome or cobalt-chrome based superalloys) tested against three solid lubricant coatings (NASA's PS212, PS300, and HVOF300). These test results are also compared to previous baseline tests conducted with plasma sprayed chrome carbide. Compared to the baseline results, no tribological benefit was achieved with the metallic bristle/solid lubricant tribopairs tested. To improve the performance of the solid lubricant coatings, issues regarding lubricant phase sizes (homogeneity), and composition need to be addressed.

Fellenstein, James A.↗
NASA NTRS2006

Development of Analytical Protocols For Organics and Isotopes Analysis on the 2009 MARS Science Laboratory.

The Mars Science Laboratory, under development for launch in 2009, is designed explore and quantitatively asses a local region on Mars as a potential habitat for present or past life. Its ambitious goals are to (1) assess the past or present biological potential of the target environment, (2) to characterize the geology and geochemistry at the MSL landing site, and (3) to investigate planetary processes that influence habitability. The planned capabilities of the rover payload will enable a comprehensive search for organic molecules, a determination of definitive mineralogy of sampled rocks and fines, chemical and isotopic analysis of both atmospheric and solid samples, and precision isotope measurements of several volatile elements. A range of contact and remote surface and subsurface survey tools will establish context for these measurements and will facilitate sample identification and selection. The Sample Analysis at Mars (SAM) suite of MSL addresses several of the mission's core measurement goals. It includes a gas chromatograph, a mass spectrometer, and a tunable laser spectrometer. These instruments will be designed to analyze either atmospheric samples or gases extracted from solid phase samples such as rocks and fines. We will describe the range of measurement protocols under development and study by the SAM engineering and science teams for use on the surface of Mars.

Mahaffy, P. R.↗
NASA NTRS2003

Two Paths from the Same Place: Task Driven and Human Centered Evolution of a Group Information Surface

This is the tale of two different implementations of a collaborative information tool, that started from the same design source. The Blueboard, developed at IBM Research, is a tool for groups to use in exchanging information in a lightweight, informal collaborative way. It began as a large display surface for walk-by use in a corporate setting and has evolved in response to task demands and user needs. At NASA, the MERBoard is being designed to support surface operations for the upcoming Mars Exploration Rover Missions. The MERBoard is a tool that was inspired by the Blueboard design, extending this design to support the collaboration requirements for viewing, annotating, linking and distributing information for the science and engineering teams that will operate two rovers on the surface of Mars. The ways in which each group transformed the system reflects not only technical requirements, but also the needs of users in each setting and embedding of the system within the larger socio-technical environment. Lessons about how task requirements, information flow requirements and work practice drive the evolution of a system are illustrated.

Russell, Daniel M.↗
DOE OSTI2024

A First-Principles Approach to Modeling Surface Site Stabilities on Multimetallic Catalysts

The study of multimetallic alloys and the multitude of possible surface compositions have sparked a tremendous interest in engineering low-cost materials with high activity and selectivity in heterogeneous catalysis. Multimetallic systems provide complementary functionalities and an unprecedented tunability when designing catalyst formulations. However, due to their immense structural and compositional complexity, the investigation and identification of an optimal catalyst is a tedious and time-consuming process, both experimentally and theoretically. Therefore, theoretical design principles are highly desirable to accelerate the screening of catalyst structures across the vast compositional space. In this paper, we introduce a simple and general model for predicting the site stability of multimetallic surfaces and nanoparticles, which is based on physical principles. The model requires only a small set of density functional theory (DFT) calculations of metal atom binding energies on monometallic and dilute alloy surface slabs to optimize the parameters in the simple model. The resulting model allows for the quantification of the stability of any particular atom site in any conceivable chemical environment across a wide range of morphologies, sizes, and arrangements by interpolating the derived parameters from a monometallic system to a completely diluted alloyed system. Herein, we demonstrate the robustness of the model across an extensive data set of transition metal alloy surfaces and 147-atoms cuboctahedral nanoparticles (NPs) composed of IrRhRu and PtPdRu. In conclusion, our approach yields mean absolute errors of ≈0.15 (IrRhRu), 0.20 (PtPdRu), 0.19 (IrRhRu NP), and 0.26 (PtPdRu NP) eV relative to site binding energies calculated using DFT.

36 MATERIALS SCIENCE↗
NASA NTRS1995

Sensors for ceramic components in advanced propulsion systems

This report includes: (1) a survey of the current methods for the measurement of surface temperature of ceramic materials suitable for use as hot section flowpath components in aircraft gas turbine engines; (2) analysis and selection of three sensing techniques with potential to extend surface temperature measurement capability beyond current limits; and (3) design, manufacture, and evaluation of the three selected techniques which include the following: platinum rhodium thin film thermocouple on alumina and mullite substrates; doped silicon carbide thin film thermocouple on silicon carbide, silicon nitride, and aluminum nitride substrates; and long and short wavelength radiation pyrometry on the substrates listed above plus yttria stabilized zirconia. Measurement of surface emittance of these materials at elevated temperature was included as part of this effort.

Koller, A. C.↗
DOE OSTI2023

Fast Surface Oxygen Release Kinetics Accelerate Nanoparticle Exsolution in Perovskite Oxides

Exsolution is a recent advancement for fabricating oxide-supported metal nanoparticle catalysts via phase precipitation out of a host oxide. A fundamental understanding and control of the exsolution kinetics are needed to engineer exsolved nanoparticles to obtain higher catalytic activity toward clean energy and fuel conversion. Since oxygen release via oxygen vacancy formation in the host oxide is behind oxide reduction and metal exsolution, we hypothesize that the kinetics of metal exsolution should depend on the kinetics of oxygen release, in addition to the kinetics of metal cation diffusion. In this report we probe the surface exsolution kinetics both experimentally and theoretically using thin-film perovskite SrTi 0.65 Fe 0.35 O 3 (STF) as a model system. We quantitatively demonstrated that in this system the surface oxygen release governs the metal nanoparticle exsolution kinetics. As a result, by increasing the oxygen release rate in STF, either by reducing the sample thickness or by increasing the surface reactivity, one can effectively accelerate the Fe 0 exsolution kinetics. Fast oxygen release kinetics in STF not only shortened the prereduction time prior to the exsolution onset, but also increased the total quantity of exsolved Fe 0 over time, which agrees well with the predictions from our analytical kinetic modeling. The consistency between the results obtained from in situ experiments and analytical modeling provides a predictive capability for tailoring exsolution, and highlights the importance of engineering host oxide surface oxygen release kinetics in designing exsolved nanocatalysts.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Pistia stratiotes L. Biochar for Sorptive Removal of Aqueous Inorganic Nitrogen

Biochar has proven effective in the remediation of excess nitrogen from soil and water. Excess nitrogen from agricultural fields ends up in aquatic systems and leads to reduced water quality and the proliferation of invasive species. This study aimed to assess the efficiency of chemically surface-modified biochar produced from invasive Pistia stratiotes L. for the adsorption of inorganic nitrogen (NH4+ and NO3−). Biochar structure was investigated using scanning electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and inductively coupled plasma mass spectrometry. The results from adsorption experiments indicate that NH4+ removal was optimal (0.8–1.3 mg N g−1) at near-neutral pH levels (6.0–7.5), while NO3− removal was optimal (0.4–0.8 mg N g−1) under acidic pH conditions (4.8–6.5) using the modified biochar. These findings highlight the significance of solution pH, biochar morphology, and surface chemistry in influencing the adsorption of NH4+ and NO3−. However, further studies are necessary to assess the potential oxidative transformation of NH4+ to NO3− by biochar, which might have contributed to the reduction in NH4+ in the aqueous phase.

36 MATERIALS SCIENCE↗
NASA NTRS1993

Aerodynamic heating environment definition/thermal protection system selection for the HL-20

Definition of the aerothermal environment is critical to any vehicle such as the HL-20 Personnel Launch System that operates within the hypersonic flight regime. Selection of an appropriate thermal protection system design is highly dependent on the accuracy of the heating-environment prediction. It is demonstrated that the entry environment determines the thermal protection system design for this vehicle. The methods used to predict the thermal environment for the HL-20 Personnel Launch System vehicle are described. Comparisons of the engineering solutions with computational fluid dynamic predictions, as well as wind-tunnel test results, show good agreement. The aeroheating predictions over several critical regions of the vehicle, including the stagnation areas of the nose and leading edges, windward centerline and wing surfaces, and leeward surfaces, are discussed. Results of predictions based on the engineering methods found within the MINIVER aerodynamic heating code are used in conjunction with the results of the extensive wind-tunnel tests on this configuration to define a flight thermal environment. Finally, the selection of the thermal protection system based on these predictions and current technology is described.

Wurster, K. E.↗
NASA NTRSDate not supplied

Glenn Extreme Environments Rig (GEER) Facility Users Guide

The Glenn Extreme Environment Rig (GEER) is a large capacity pressure vessel capable of simulating high pressure and temperature conditions with a specified, custom mixture of gas. The chamber is certified for operation in physical and chemical conditions representative of the surface conditions of Venus. It can accommodate large scientific or engineering test articles while maintaining the specified conditions indefinitely. The user-configurable gas supply is capable of handling a mixture of up to nine independent streams for injection directly into the vessel. GEER is supported in part by NASA’s Planetary Science Division under the Science Mission Directorate and is available for use by the commercial, academic, and research communities. GEER was operationally commissioned in November of 2014. At that time, it successfully maintained the temperature, pressure, and chemistry of the Venus surface atmosphere. In the spring of 2015, GEER began operations for engineering and scientific research. Since then, over 20 tests have been successfully conducted in the chamber with a variety of atmospheric test conditions.

Blake W. Beckley↗
NASA NTRS1992

Design issues for lunar in situ aluminum/oxygen propellant rocket engines

Design issues for lunar ascent and lunar descent rocket engines fueled by aluminum/oxygen propellant produced in situ at the lunar surface were evaluated. Key issues are discussed which impact the design of these rockets: aluminum combustion, throat erosion, and thrust chamber cooling. Four engine concepts are presented, and the impact of combustion performance, throat erosion and thrust chamber cooling on overall engine design are discussed. The advantages and disadvantages of each engine concept are presented.

Meyer, Michael L.↗
NASA NTRS1992

Design issues for lunar in situ aluminum/oxygen propellant rocket engines

Design issues for lunar ascent and lunar descent rocket engines fueled by aluminum/oxygen propellant produced in situ at the lunar surface were evaluated. Key issues are discussed which impact the design of these rockets: aluminum combustion, throat erosion, and thrust chamber cooling. Four engine concepts are presented, and the impact of combustion performance, throat erosion and thrust chamber cooling on overall engine design are discussed. The advantages and disadvantages of each engine concept are presented.

Meyer, Michael L.↗