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All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Advanced Unstructured Grid Generation for Complex Aerodynamic Applications

A new approach for distribution of grid points on the surface and in the volume has been developed and implemented in the NASA unstructured grid generation code VGRID. In addition to the point and line sources of prior work, the new approach utilizes surface and volume sources for automatic curvature-based grid sizing and convenient point distribution in the volume. A new exponential growth function produces smoother and more efficient grids and provides superior control over distribution of grid points in the field. All types of sources support anisotropic grid stretching which not only improves the grid economy but also provides more accurate solutions for certain aerodynamic applications. The new approach does not require a three-dimensional background grid as in the previous methods. Instead, it makes use of an efficient bounding-box auxiliary medium for storing grid parameters defined by surface sources. The new approach is less memory-intensive and more efficient computationally. The grids generated with the new method either eliminate the need for adaptive grid refinement for certain class of problems or provide high quality initial grids that would enhance the performance of many adaptation methods.

Pirzadeh, Shahyar Z.↗
NASA NTRS2009

An LED Approach for Measuring the Photocatalytic Breakdown of Crystal Violet Dye

A simple technique to assess the reactivity of photocatalytic coatings sprayed onto transmissive glass surfaces was developed. This new method uses ultraviolet (UV) gallium nitride (GaN) light-emitting diodes (LEDs) to drive a photocatalytic reaction (the photocatalytic breakdown of a UV-resistant dye applied to a surface coated with the semiconductor titanium dioxide); and then a combination of a stabilized white light LED and a spectrometer to track the dye degradation as a function of time. Simple, standardized evaluation techniques that assess photocatalytic materials over a variety of environmental conditions, including illumination level, are not generally available and are greatly needed prior to in situ application of photocatalytic technologies. To date, much research pertaining to this aspect of photocatalysis has been limited and has focused primarily on laboratory experiments using mercury lamps. Mercury lamp illumination levels are difficult to control over large ranges and are temporally modulated by line power, limiting their use in helping to understand and predict how photocatalytic materials will behave in natural environmental settings and conditions. The methodology described here, using steady-state LEDs and time series spectroradiometric techniques, is a novel approach to explore the effect of UV light on the photocatalytic degradation of a UV resistant dye (crystal violet). GaN UV LED arrays, centered around 365 nm with an adjustable DC power supply, are used to create a small, spatially uniform light field where the steady state light level can be varied over three to four orders of magnitude. For this study, a set of glass microscope slides was custom coated with a thinly sprayed layer of photocatalytic titanium dioxide. Crystal violet was then applied to these titanium-dioxide coated slides and to uncoated control slides. The slides were then illuminated at various light levels from the dye side of the slide by the UV LED array. To monitor dye degradation on the slides over time, a temperature-stabilized white light LED was used to illuminate the opposite side of the slides. As the dye degraded, the amount of light from the white light LED transmitted through the slide was monitored with a spectrometer and subsequently analyzed to determine and compare the rate of dye degradation for photocatalytically coated versus uncoated slide surfaces. The long-term stability of the spectrometer/white light LED combination, which required only a single reference spectra to be taken for a time series sequence of several hours, enabled accurate measurements of transmitted light over time. Time series transmission curves were generated and results demonstrated that over time the transmission increased much more rapidly on the coated slides than on the control slides. This experimental configuration and methodology for photocatalytic activity measurement minimizes many external variable effects and allows low light level studies to be performed. This study also compares the advantages of this novel LED light source design to traditional mercury lamp systems and non-LED lamp approaches that have conventionally been used. The methodology and experimental design research summarized in this abstract is partly funded by the Department of Homeland Security, Science and Technology Directorate, and by the NASA Stennis Space Center Innovative Partnerships Program.

Ryan, Robert E.↗
NASA NTRS2010

Advanced Unstructured Grid Generation for Complex Aerodynamic Applications

A new approach for distribution of grid points on the surface and in the volume has been developed. In addition to the point and line sources of prior work, the new approach utilizes surface and volume sources for automatic curvature-based grid sizing and convenient point distribution in the volume. A new exponential growth function produces smoother and more efficient grids and provides superior control over distribution of grid points in the field. All types of sources support anisotropic grid stretching which not only improves the grid economy but also provides more accurate solutions for certain aerodynamic applications. The new approach does not require a three-dimensional background grid as in the previous methods. Instead, it makes use of an efficient bounding-box auxiliary medium for storing grid parameters defined by surface sources. The new approach is less memory-intensive and more efficient computationally. The grids generated with the new method either eliminate the need for adaptive grid refinement for certain class of problems or provide high quality initial grids that would enhance the performance of many adaptation methods.

Pirzadeh, Shahyar↗
NASA NTRS2007

Java Programming Language

The Java seminar covers the fundamentals of Java programming language. No prior programming experience is required for participation in the seminar. The first part of the seminar covers introductory concepts in Java programming including data types (integer, character, ..), operators, functions and constants, casts, input, output, control flow, scope, conditional statements, and arrays. Furthermore, introduction to Object-Oriented programming in Java, relationships between classes, using packages, constructors, private data and methods, final instance fields, static fields and methods, and overloading are explained. The second part of the seminar covers extending classes, inheritance hierarchies, polymorphism, dynamic binding, abstract classes, protected access. The seminar conclude by introducing interfaces, properties of interfaces, interfaces and abstract classes, interfaces and cailbacks, basics of event handling, user interface components with swing, applet basics, converting applications to applets, the applet HTML tags and attributes, exceptions and debugging.

Shaykhian, Gholam Ali↗
NASA NTRS2014

Preparation and Integration of ALHAT Precision Landing Technology for Morpheus Flight Testing

The Autonomous precision Landing and Hazard Avoidance Technology (ALHAT) project has developed a suite of prototype sensors for enabling autonomous and safe precision land- ing of robotic or crewed vehicles on solid solar bodies under varying terrain lighting condi- tions. The sensors include a Lidar-based Hazard Detection System (HDS), a multipurpose Navigation Doppler Lidar (NDL), and a long-range Laser Altimeter (LAlt). Preparation for terrestrial ight testing of ALHAT onboard the Morpheus free- ying, rocket-propelled ight test vehicle has been in progress since 2012, with ight tests over a lunar-like ter- rain eld occurring in Spring 2014. Signi cant work e orts within both the ALHAT and Morpheus projects has been required in the preparation of the sensors, vehicle, and test facilities for interfacing, integrating and verifying overall system performance to ensure readiness for ight testing. The ALHAT sensors have undergone numerous stand-alone sensor tests, simulations, and calibrations, along with integrated-system tests in special- ized gantries, trucks, helicopters and xed-wing aircraft. A lunar-like terrain environment was constructed for ALHAT system testing during Morpheus ights, and vibration and thermal testing of the ALHAT sensors was performed based on Morpheus ights prior to ALHAT integration. High- delity simulations were implemented to gain insight into integrated ALHAT sensors and Morpheus GN&C system performance, and command and telemetry interfacing and functional testing was conducted once the ALHAT sensors and electronics were integrated onto Morpheus. This paper captures some of the details and lessons learned in the planning, preparation and integration of the individual ALHAT sen- sors, the vehicle, and the test environment that led up to the joint ight tests.

Carson, John M., III↗
NASA NTRS2017

NASA's In-Space Manufacturing Project: Development of a Multimaterial, Multiprocess Fabrication Laboratory for the International Space Station

NASA's long term goal is to send humans to Mars. Over the next two decades, NASA will work with private industry to develop and demonstrate the technologies and capabilities needed to support exploration of the red planet by humans and ensure their safe return to earth. To accomplish this goal, NASA is employing a capability driven approach to its human spaceflight strategy. This approach will develop a suite of evolving capabilities which provide specific functions to solve exploration challenges. One challenge that is critical to sustainable and safer exploration is the ability to manufacture and recycle materials in space. This paper provides an overview of NASA's in-space manufacturing project, its past and current activities, and how technologies under development will ultimately culminate in a multimaterial, multiprocess fabrication laboratory ('FabLab') to be deployed on the International Space Station in the early 2020s. ISM is a critical capability for the long endurance missions NASA seeks to undertake in the coming decades. An unanticipated failure that can be adapted for in low earth orbit may result in a loss of mission in transit to Mars. In order to have a suite of functional ISM capabilities that are compatible with NASA's exploration timeline, ISM must be equipped with the resources necessary to develop these technologies and deploy them for testing prior to the scheduled de-orbit of ISS in 2024. The paper will discuss the phased approach to FabLab development, desired capabilities, and requirements for the hardware. The FabLab will move NASA and private industry significantly closer to changing historical paradigms for human spaceflight where all materials used in space are launched from earth. While the FabLab will be tested on ISS, the system is ultimately intended for use in a deep space habitat or transit vehicle.

Prater, T.↗
NASA NTRS2017

NASA's In-Space Manufacturing Project: A Roadmap for a Multimaterial Fabrication Laboratory in Space

Human space exploration to date has been limited to low Earth orbit and the moon. The International Space Station (ISS) provides a unique opportunity for NASA to partner with private industry for development and demonstration of the technologies needed to support exploration initiatives. One challenge that is critical to sustainable and safer exploration is the ability to manufacture and recycle materials in space. This paper provides an overview of NASA's in-space manufacturing (ISM) project, its past and current activities (2014-2017), and how technologies under development will ultimately culminate in a multimaterial fabrication laboratory ("ISM FabLab") to be deployed on the International Space Station in the early 2020s. ISM is a critical capability for the long endurance missions NASA seeks to undertake in the coming decades. An unanticipated failure that can be adapted for in low earth orbit, through a resupply launch or a return to earth, may instead result in a loss of mission while in transit to Mars. To have a suite of functional ISM capabilities that are compatible with NASA's exploration timeline, ISM must be equipped with the resources necessary to develop these technologies and deploy them for testing prior to the scheduled de-orbit of ISS in 2024. The presentation provides a broad overview of ISM projects activities culminating with the Fabrication Laboratory for ISS. In 2017, the in-space manufacturing project issued a broad agency announcement for this capability. Requirements of the Fabrication Laboratory as stated in the solicitation will be discussed. The FabLab will move NASA and private industry significantly closer to changing historical paradigms for human spaceflight where all materials used in space are launched from earth. While the current ISM FabLab will be tested on ISS, future systems are eventually intended for use in a deep space habitat or transit vehicle. The work of commercial companies funded under NASA's Small Business Innovative Research Program (SBIR) is also discussed, as these activities, from development of recyclable packaging for ISS to additive manufacturing capabilities for metals and electronics, could also potentially be infused into future exploration capabilities. Key data from ISM projects to date will also be summarized.

Prater, Tracie↗
NASA NTRS2018

NASA's In-Space Manufacturing Project: Toward a Multimaterial Fabrication Laboratory for the International Space Station

uman space exploration to date has been limited to low Earth orbit and the moon. The International Space Station (ISS) provides a unique opportunity for NASA to partner with private industry for development and demonstration of the technologies needed to support exploration initiatives. One challenge that is critical to sustainable and safer exploration is the ability to manufacture and recycle materials in space. This paper provides an overview of NASA's in-space manufacturing (ISM) project, its past and current activities, and how technologies under development will ultimately culminate in a multimaterial fabrication laboratory ("ISM FabLab") to be deployed on the International Space Station in the early 2020s. ISM is a critical capability for the long endurance missions NASA seeks to undertake in the coming decades. An unanticipated failure that can be adapted for in low earth orbit, through a resupply launch or a return to earth, may instead result in a loss of mission while in transit to Mars. To have a suite of functional ISM capabilities that are compatible with NASA's exploration timeline, ISM must be equipped with the resources necessary to develop these technologies and deploy them for testing prior to the scheduled de-orbit of ISS in 2024. The paper provides a broad overview of ISM projects activities culminating with the Fabrication Laboratory for ISS. The FabLab will move NASA and private industry significantly closer to changing historical paradigms for human spaceflight where all materials used in space are launched from earth. While the current ISM FabLab will be tested on ISS, future systems are eventually intended for use in a deep space habitat or transit vehicle. The work of commercial companies funded under NASA's Small Business Innovative Research Program (SBIR) is also discussed, as these activities, from development of recyclable packaging for ISS to additive manufacturing capabilities for metals and electronics, could also potentially be infused into FabLab exploration capabilities as well.

Prater, Tracie↗
NASA NTRS2022

Ultra-Pure, High Endurance Liquid Bladder with Volume Sensor for Space Applications

The NASA Portable Life Support System (PLSS) for the Exploration Extravehicular Mobility Unit (xEMU) incorporates a Feedwater Supply Assembly (FSA) to store consumable cooling water. The FSA accepts pure water prior to each Extra-Vehicular Activity (EVA), then supplies this water to a membrane evaporator at ambient suit pressure during the eight hour EVA. The FSA must function reliably for hundreds of EVAs over 15 years of service without introducing contamination that may accumulate and foul the membrane. We present a unique design that combines the benefits of a flexible fluoropolymer bladder with the strength and convenience of a rigid tank, providing an ultra-pure, ambient-pressure reservoir with fill-drain cycle life exceeding 3000, internal pressure tolerance exceeding 100 psi, high volumetric efficiency, near-zero dead volume, optical transparency for visual inspection, simplified mounting, and very low mass. We also incorporate a novel volume sensor suitable for both microgravity and arbitrarily accelerated environments and capable of real-time monitoring with accuracy on the order of 2.5% full scale. Analytical predictions are supported by experimental test data from a mature subscale prototype.

PLSS Portable Life Support System FSA Feedwater Su↗
NASA NTRS2022

MOA-2020-BLG-135Lb: A New Neptune-class Planet for the Extended MOA-II Exoplanet Microlens Statistical Analysis

We report the light-curve analysis for the event MOA-2020-BLG-135, which leads to the discovery of a new Neptune-class planet, MOA-2020-BLG-135Lb. With a derived mass ratio of q=1.52 +0.39 -0.31 x10 -4 and separation s ≈ 1, the planet lies exactly at the break and likely peak of the exoplanet mass-ratio function derived by the Microlensing Observations in Astrophysics (MOA) Collaboration. We estimate the properties of the lens system based on a Galactic model and considering two different Bayesian priors: one assuming that all stars have an equal planet-hosting probability and the other that planets are more likely to orbit more-massive stars. With a uniform host mass prior, we predict that the lens system is likely to be a planet of mass m planet = 11.3 +19.2 -6.9 M ⨁ and a host star of mass M host =0.23 +0.39 -0.14 M ⨀ , located at a distance 𝐃 𝐋 =7.9 +1.0 -1.0 kpc. With a prior that holds that planet occurrence scales in proportion to the host-star mass, the estimated lens system properties are m planet =25 +22 -15 M ⨁ , M M host =0.53 +0.42 -0,32 M ⨀ , and D L =8.3 +0.9 -1.0 .This planet qualifies for inclusion in the extended MOA-II exoplanet microlens sample.

Gravitational microlensing↗
NASA NTRS2014

De Novo Synthesis and Functional Study of Primitive Polypeptides in the Prebiotic Protein World

DNA, RNA and proteins within a lipid-bound membrane are the core components of life, but the order of their appearance during the origin of life is still under debate. The widely accepted RNA World hypothesis states that RNA likely emerged prior to proteins and DNA since RNA can serve both replicative and catalytic roles. While biochemists have reproduced the synthesis, polymerization, and replication of nucleotides and RNA under controlled prebiotic conditions, it is clear that such complex organic molecules were are not present in significant amounts in the the starting prebiotic material on Earth either from endogenous production or meteoritic input. In contrast, amino acids are naturally abundant in various prebiotic contexts such as carbonaceous chondrites and Urey-Miller type experiments, and many studies have demonstrated that under plausible prebiotic conditions amino acids could condense or polymerize to give rise to short peptides. These findings support the basis of a Protein World hypothesis for life, however little has been done to study the functions of such primitive peptides. Here we present our novel synthetic biology-based approach to the de novo synthesis of billions of primitive peptidesproteins derived from a limited set of naturally abundant proteinogenic amino acids such as glycine, alanine, aspartic acid, glutamic acid, valine and serine. Of these peptides, the ones with divalent metal-binding capability are of particular interest and will be screened and identified. Certain divalent metals were likely present in prebiotic environments. Not only do they coordinate well with amino acids, but they also catalyze reactions, which are difficult to achieve in organic chemistry. Since D-chiral and non-proteinogenic amino acids are also abundant in the universe and may provide insight into the pathway by which life developed, we will also discuss methods to analyze primitive peptides consisting of these amino acids and D-chiral and non-proteinogenic amino acids. By understanding this naturalistic pathway, we will be able to better understand how life developed here on Earth. Since these amino acids are abundant in universe, this work provide insight into pathways by which life developed on Earth and, by extension, the probability of life arising elsewhere.

Fujishima, Kosuke↗
NASA NTRS2005

IVHM Framework for Intelligent Integration for Vehicle Health Management

Integrated Vehicle Health Management (IVHM) systems for aerospace vehicles, is the process of assessing, preserving, and restoring system functionality across flight and techniques with sensor and communication technologies for spacecraft that can generate responses through detection, diagnosis, reasoning, and adapt to system faults in support of Integrated Intelligent Vehicle Management (IIVM). These real-time responses allow the IIVM to modify the affected vehicle subsystem(s) prior to a catastrophic event. Furthermore, this framework integrates technologies which can provide a continuous, intelligent, and adaptive health state of a vehicle and use this information to improve safety and reduce costs of operations. Recent investments in avionics, health management, and controls have been directed towards IIVM. As this concept has matured, it has become clear that IIVM requires the same sensors and processing capabilities as the real-time avionics functions to support diagnosis of subsystem problems. New sensors have been proposed, in addition to augment the avionics sensors to support better system monitoring and diagnostics. As the designs have been considered, a synergy has been realized where the real-time avionics can utilize sensors proposed for diagnostics and prognostics to make better real-time decisions in response to detected failures. IIVM provides for a single system allowing modularity of functions and hardware across the vehicle. The framework that supports IIVM consists of 11 major on-board functions necessary to fully manage a space vehicle maintaining crew safety and mission objectives. These systems include the following: Guidance and Navigation; Communications and Tracking; Vehicle Monitoring; Information Transport and Integration; Vehicle Diagnostics; Vehicle Prognostics; Vehicle Mission Planning, Automated Repair and Replacement; Vehicle Control; Human Computer Interface; and Onboard Verification and Validation. Furthermore, the presented framework provides complete vehicle management which not only allows for increased crew safety and mission success through new intelligence capabilities, but also yields a mechanism for more efficient vehicle operations.

Paris, Deidre↗
NASA NTRS1972

Flow field measurements for space-shuttle-related cylindrical configurations in hypersonic streams.

Use of surface pressures, heat-transfer rates, and flow-visualization photographs to define the flowfields for simulated infinite cylinders. Four cylindrical cross sections were studied in the experimental program, which was conducted at free-stream Mach numbers of 5 to 15, free-stream unit Reynolds numbers from 2 to 20 million per foot, and angles of attack from 30 to 90 deg. Although swept-cylinder theory provides a reasonable correlation of the measured laminar heat-transfer rates in the plane of symmetry, improved correlation with the measurements is obtained if the three-dimensional nature of the flow is taken into account. In cases where the boundary layer on the windward forebody was turbulent, the large velocity gradients near the chines produced relaminarization of the boundary layer prior to separation. The average heat-transfer-rate in the separated region, which is weakly dependent on the free-stream conditions, was found to be a linear function of the angle of attack. For a given flow condition the effect of the leeward geometry on heat transfer can be correlated by a single geometric parameter which is dependent on the location of separation.

Bertin, J. J.↗
NASA NTRS1981

Effects of misalignment on mechanical behavior of metals in creep

Creep tests were conducted by means of a closed loop servocontrolled materials test system. The strain history prior to creep is carefully monitored. Tests were performed for aluminum alloy 6061-O at 150 C and were monitored by a PDP 11/04 minicomputer at a preset constant plastic strain rate prehistory. The results show that the plastic strain rate prior to creep plays a significant role in creep behavior. The endochronic theory of viscoplasticity was applied to describe the observed creep curves. Intrinsic time and strain rate sensitivity function concepts are employed and modified according to the present observation.

Wu, H. C.↗
NASA NTRS1997

A Technique for Transient Thermal Testing of Thick Structures

A new open-loop heat flux control technique has been developed to conduct transient thermal testing of thick, thermally-conductive aerospace structures. This technique uses calibration of the radiant heater system power level as a function of heat flux, predicted aerodynamic heat flux, and the properties of an instrumented test article. An iterative process was used to generate open-loop heater power profiles prior to each transient thermal test. Differences between the measured and predicted surface temperatures were used to refine the heater power level command profiles through the iteration process. This iteration process has reduced the effects of environmental and test system design factors, which are normally compensated for by closed-loop temperature control, to acceptable levels. The final revised heater power profiles resulted in measured temperature time histories which deviated less than 25 F from the predicted surface temperatures.

Horn, Thomas J.↗
NASA NTRS2000

The Effects of Thermal History on Nucleation of Tetragonal Lysozyme Crystals, or Hot Protein and Cold Nucleation

Chicken egg white lysozyme has a well characterized thermally driven phase transition. Between pH 4.2 and 5.2, the transition temperature, as defined by the point where the tetragonal and orthorhombic solubilities are equal, is a function of the pH, salt (precipitant) type and concentration, and most likely of the buffer concentration as well. This phase transition can be carried out with protein solution alone, prior to addition of precipitant solution. Warming a lysozyme solution above the phase transition point, then cooling it back below this point, has been shown to affect the subsequent nucleation rate, as determined by the numbers and size of crystals formed, but not the growth rate for the tetragonal crystal form . We have now measured the kinetics of this process and investigated its reversibility. The transition effects are progressive with temperature, having a half time of about 1 hour at 37C at pH 4.8. After holding a lysozyme solution at 37C (prior to addition of precipitant) for 16 hours, then cooling it back to 4C no return to the pre-warmed nucleation kinetics are observed after at least 4 weeks. Orthorhombic lysozyme crystals apparently do not undergo the flow-induced growth cessation of tetragonal lysozyme crystals. Putting the protein in the orthorhombic form does not affect the averaged face growth kinetics, only nucleation, for tetragonal crystals. This differential behaviour may be exploited to elucidate how and where flow affects the lysozyme crystal growth process. The presentation will focus on the results of these and ongoing studies in this area.

Burke, Michael↗
NASA NTRS1998

Stress, Aging and Thirst

After growth during adolesence, total body water decreases progressively with aging from 65% of body weight to about 53% of body weight in the 70th decade; a majority of the loss occurs from the extracellular volume, from 42% to about 25%, respectively. Cellular volume also reaches equilibrium in the 70th decade at about 25% of body weight. Various stresses such as exercise, heat and attitude exposure, ad prior dehydration attenuate voluntary fluid intake (involuntary dehydration). Voluntary fluid intake appears to decrease with aging (involuntary dehydration in this sense aging can be considered as a stress. Kidney function and muscle mass (80% water) decrease somewhat with aging, and voluntary fluid intake (thirst) is also attenuated. Thirst is stimulated by increasing osmolality (hypernatremia) of the extracellular fluid and by decreased extracellular volume (mainly plasma volume) which act to increase intracellular fluid volume osmolality to activiate drinking. The latter decreases fluid compartment osmolality which ' It terminates drinking. However, this drinking mechanism seems to be attenuated with aging such that increasing plasma osmolality no longer stimulates fluid intake appropriately. Hypernatremia in the elderly has been associated all too frequently with greater incidence of bacterial infection and increased mortality. Involuntary dehydration can be overcome in young men by acclimation to an intermittent exercise-in-heat training program. Perhaps exercise training in the elderly would also increase voluntary fluid intake and increase muscle mass to enhance retention of water.

Greenleaf, John E.↗
NASA NTRS2007

Orion Cislunar Guidance and Navigation

The Orion vehicle is being designed to provide nominal crew transport to the lunar transportation stack in low Earth orbit, crew abort prior during transit to the moon, and crew return to Earth once lunar orbit is achieved. Design of guidance and navigation algorithms to perform maneuvers in support of these functions is dependent on the support provided by navigation infrastructure, the performance of the onboard GN&C system, and the choice of trajectory maneuver methodology for outbound and return mission phases. This paper documents the preliminary integrated analyses performed by members of the Orion Orbit GN&C System team investigating the navigation update accuracy of a modern equivalent to the Apollo era ground tracking network and the expected onboard dispersion and navigation errors during a lunar mission using a linear covariance error analysis technique.

D'Souza, Christopher↗