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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

Characterization of Space Shuttle Thermal Protection System (TPS) Materials for Return-to-Flight following the Shuttle Columbia Accident Investigation

During the Space Shuttle Columbia Accident Investigation, it was determined that a large chunk of polyurethane insulating foam (= 1.67 lbs) on the External Tank (ET) came loose during Columbia's ascent on 2-1-03. The foam piece struck some of the protective Reinforced Carbon-Carbon (RCC) panels on the leading edge of Columbia's left wing in the mid-wing area. This impact damaged Columbia to the extent that upon re-entry to Earth, superheGed air approaching 3,000 F caused the vehicle to break up, killing all seven astronauts on board. A paper after the Columbia Accident Investigation highlighted thermal analysis testing performed on External Tank TPS materials (1). These materials included BX-250 (now BX-265) rigid polyurethane foam and SLA-561 Super Lightweight Ablator (highly-filled silicone rubber). The large chunk of foam from Columbia originated fiom the left bipod ramp of the ET. The foam in this ramp area was hand-sprayed over the SLA material and various fittings, allowed to dry, and manually shaved into a ramp shape. In Return-to-Flight (RTF) efforts following Columbia, the decision was made to remove the foam in the bipod ramp areas. During RTF efforts, further thermal analysis testing was performed on BX-265 foam by DSC and DMA. Flat panels of foam about 2-in. thick were sprayed on ET tank material (aluminum alloys). The DSC testing showed that foam material very close to the metal substrate cured more slowly than bulk foam material. All of the foam used on the ET is considered fully cured about 21 days after it is sprayed. The RTF culminated in the successful launch of Space Shuttle Discovery on 7-26-05. Although the flight was a success, there was another serious incident of foam loss fiom the ET during Shuttle ascent. This time, a rather large chunk of BX-265 foam (= 0.9 lbs) came loose from the liquid hydrogen (LH2) PAL ramp, although the foam did not strike the Shuttle Orbiter containing the crew. DMA testing was performed on foam samples taken fiom a simulated PAL ramp panel. It was found that the smooth rind on the foam facing the cable tray did significantly affect the properties of foam at the PAL ramp surface. The smooth rind increased the storage modulus E' of the foam as much as 20- 40% over a temperature range of -145 to 95 C. Because of foam loss fiom the PAL ramp, future Shuttle flights were grounded indefinitely to allow further testing to better understand foam properties. The decision was also made to remove foam from the LH2 PAL, ramp. Other RTF efforts prior to the launch of Discovery included

Wingard, Doug↗
NASA NTRS2003

Manipulation of Micro Scale Particles in Optical Traps Using Programmable Spatial Light Modulation

1064 nm light, from an Nd:YAG laser, was polarized and incident upon a programmable parallel aligned liquid crystal spatial light modulator (PAL-SLM), where it was phase modulated according to the program controlling the PAL-SLM. Light reflected from the PAL-SLM was injected into a microscope and focused. At the focus, multiple optical traps were formed in which 9.975 m spheres were captured. The traps and the spheres were moved by changing the program of the PAL-SLM. The motion of ordered groups of micro particles was clearly demonstrated.

Seibel, Robin E.↗
NASA NTRS2008

Estimation of the Unsteady Aerodynamic Load on Space Shuttle External Tank Protuberances from a Component Wind Tunnel Test

At the wake of the Columbia (STS-107) accident it was decided to remove the Protuberance Aerodynamic Load (PAL) Ramp that was originally intended to protect various protuberances outside of the Space Shuttle External Tank from high buffet load induced by cross-flows at transonic speed. In order to establish the buffet load without the PAL ramp, a wind tunnel test was conducted where segments of the protuberances were instrumented with dynamic pressure transducers; and power-spectra of sectional lift and drag forces at various span-wise locations between two adjacent support brackets were measured under different cross flow angles, Mach number and other conditions. Additionally, frequency-dependent spatial correlations between the sectional forces were also established. The sectional forces were then adjusted by the correlation length to establish span-averaged spectra of normal and lateral forces that can be suitably "added" to various other unsteady forces encountered by the protuberance. This paper describes the methodology used for calculating the correlation-adjusted power spectrum of the buffet load. A second part of the paper describes wind-tunnel results on the difference in the buffet load on the protuberances with and without the PAL ramp. In general when the ramp height is the same as that of the protuberance height, such as that found on the liquid Oxygen part of the tank, the ramp is found to cause significant reduction of the unsteady aerodynamic load. However, on the liquid Hydrogen part of the tank, where the Oxygen feed-line is far larger in diameter than the height of the PAL ramp, little protection is found to be available to all but the Cable Tray.

Panda, J.↗
NASA NTRS2008

Estimation of the Unsteady Aerodynamic Load on Space Shuttle External Tank Protuberances from a Component Wind Tunnel Test

At the wake of the Columbia (STS-107) accident it was decided to remove the Protuberance Aerodynamic Load (PAL) Ramp that was originally intended to protect various protuberances outside of the Space Shuttle External Tank from high buffet load induced by cross-flows at transonic speed. In order to establish the buffet load without the PAL ramp, a wind tunnel test was conducted where segments of the protuberances were instrumented with dynamic pressure transducers; and power-spectra of sectional lift and drag forces at various span-wise locations between two adjacent support brackets were measured under different cross flow angles, Mach number and other conditions. Additionally, frequency-dependent spatial correlations between the sectional forces were also established. The sectional forces were then adjusted by the correlation length to establish span-averaged spectra of normal and lateral forces that can be suitably "added" to various other unsteady forces encountered by the protuberance. This paper describes the methodology used for calculating the correlation-adjusted power spectrum of the buffet load. A second part of the paper describes wind-tunnel results on the difference in the buffet load on the protuberances with and without the PAL ramp. In general when the ramp height is the same as that of the protuberance height, such as that found on the liquid Oxygen part of the tank, the ramp is found to cause significant reduction of the unsteady aerodynamic load. However, on the liquid Hydrogen part of the tank, where the Oxygen feed-line is far larger in diameter than the height of the PAL ramp, little protection is found to be available to all but the Cable Tray.

Panda, Jayatana↗
NASA NTRS2022

Vision-Based Precision Approach and Landing for Advanced Air Mobility

Advanced Air Mobility (AAM) aircraft require perception systems for precision approach and landing systems (PALS) in urban, suburban, rural, and regional environments. The current state-of-the-art methods approved for automated approach and landing will be difficult to utilize in support of AAM operational concepts. However, there are technology and systems from other applications and lower-TRL research that use vision, IR, radar, and GPS methods to provide baseline perception and sensing requirements for AAM aircraft approach and landing. This paper focuses on vision-based PAL to demonstrate a closed-loop baseline controller while adhering to the Federal Aviation Administration requirements and regulations. The coplanar algorithm determines pose estimation, which feeds into an Extended Kalman filter. Combining IMU with vision creates a sensor fusion navigation solution for GPS-denied environments. The state estimate leads to glideslope and localizer error computations, which will be pertinent for designing and deriving guidance laws and control laws for AAM PALS. The IMU and vision navigation solution provides promising simulation results for AAM PALS, and higher fidelity simulations will include computer graphics rendering and feature correspondence.

Evan Kawamura↗
NASA NTRSDate not supplied

Distributed Sensing and Computer Vision Methods for Advanced Air Mobility Approach and Landing

Advanced Air Mobility (AAM) aircraft require precision approach and landing systems (PALS) in several types of environments such as urban, suburban, and rural. It is difficult to implement current state-of-the-art methods approved for automated approach and landing for AAM operations. However, existing technology and systems that use vision, IR, radar, and GPS methods provide baseline perception and sensing requirements for AAM aircraft approach and landing. This paper focuses on vision-based PAL and computer vision feature correspondence methods to demonstrate a baseline navigation system while adhering to the Federal Aviation Administration requirements and regulations. The coplanar algorithm determines pose estimation, which feeds into an Extended Kalman filter that combines IMU with vision to create a sensor fusion navigation solution for GPS-denied environments. The state estimate leads to glideslope and localizer error computations, which will be pertinent for designing and deriving guidance laws and control laws for AAM PALS. The IMU and vision navigation solution provides promising simulation results for AAM PALS. This paper builds on previous work by incorporating high fidelity simulations with computer graphics rendering to demonstrate a distributed sensor network to track an AAM aircraft during approach and landing to compare with the aircraft's onboard navigation solution.

Evan Kawamura↗
NASA NTRSDate not supplied

VSLAM and Vision-based Approach and Landing for Advanced Air Mobility

Advanced Air Mobility (AAM) aircraft have many challenges in landing accurately and safely in urban, suburban, and rural environments. Localization in large and open rural environments could utilize GPS, but AAM aircraft in urban environments will encounter GPS degradation. Another challenge involves flight operation time, i.e., flying during the day or at night. There are different guidelines, landmarks, and landing light configurations at runways, heliports, and vertiports for daytime and nighttime applications. Tailoring feature detection methods for AAM approach and landing during the day and night pose different issues and challenges. It is easier to detect edges, lines, and other runway markers during the day than at night. Conversely, it is easier to see landing light configurations and patterns at nighttime than daytime. Consequently, utilizing the same feature detector for daytime and nighttime operations may not be feasible. This paper focuses on a vision-based precision approach and landing (PAL) by comparing ORB SLAM 2, a Vision Simultaneous Localization and Mapping (VSLAM) algorithm, and a novel EKF that combines onboard IMU measurements with coplanar pose from orthography and scaling with iterations (COPOSIT). Conducting unmanned aerial system (UAS) flight tests at NASA Armstrong Flight Research Center (AFRC) with landmarks and fiducials distributed around the landing zone provides a simulated AAM approach and landing data to test vision-based PAL methods to provide Alternative Position, Navigation, and Timing (APNT) solutions for AAM PAL applications. The novel vision-based PAL EKF with IMU and COPOSIT provides accurate state estimation when distributed landmarks and fiducials are in the field of view.

distributed sensing↗
DOE OSTI2024

Dynamic Scaling Analysis of Accelerated Irradiation Testing on Additive Manufacturing Materials by Positron Annihilation

The timely applications of Additive Manufacturing (AM) materials in nuclear environments require accelerated irradiation tests, mainly ion irradiation to enable rapid prototyping. Low dose ion irradiation would cause sub-nanostructure changes by generation of lattice defects, vacancies, vacancy clusters and voids and void swelling caused by cellular dislocations. Positron Annihilation Lifetime (PAL), a novel technology, sensitive towards sub-nanostructure morphology with high accuracy (about 10-7 vacancy per atom), supported by Transition Electron Microscope (TEM) would be applied to identify the type and total size of the defects. The subsequent PAL measurements and TEM surface studies would be followed by PAL analysis that includes sophisticated trapping model. The PAS results would become an input to dynamic scaling analysis (that predicts radiation effects from low dose studies for high dose effects), which incorporate mean-field theory model. The final effect is an in-depth understanding of the microstructure evolution of AM materials under ion irradiation which can be extrapolated to the studies of neutron irradiation, since ion-irradiation takes less time and do not cause the irradiation hazard. The working hypothesis is that PAL technology, that have excellent sensitivity to low-defect concentration would help to identify ion-induced material damage on the atomic and nano-scale level, which then could be extrapolated to understand the neutron damage better.

accelerated irradiation testing↗
DOE OSTI2023

The role of CenKR in the coordination of Rhodobacter sphaeroides cell elongation and division

ABSTRACT Cell elongation and division are essential aspects of the bacterial life cycle that must be coordinated for viability and replication. The impact of misregulation of these processes is not well understood as these systems are often not amenable to traditional genetic manipulation. Recently, we reported on the CenKR two-component system (TCS) in the Gram-negative bacterium Rhodobacter sphaeroides that is genetically tractable, widely conserved in α-proteobacteria, and directly regulates the expression of components crucial for cell elongation and division, including genes encoding subunit of the Tol-Pal complex. In this work, we show that overexpression of cenK results in cell filamentation and chaining. Using cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET), we generated high-resolution two-dimensional (2D) images and three-dimensional (3D) volumes of the cell envelope and division septum of wild-type cells and a cenK overexpression strain finding that these morphological changes stem from defects in outer membrane (OM) and peptidoglycan (PG) constriction. By monitoring the localization of Pal, PG biosynthesis, and the bacterial cytoskeletal proteins MreB and FtsZ, we developed a model for how increased CenKR activity leads to changes in cell elongation and division. This model predicts that increased CenKR activity decreases the mobility of Pal, delaying OM constriction, and ultimately disrupting the midcell positioning of MreB and FtsZ and interfering with the spatial regulation of PG synthesis and remodeling. IMPORTANCE By coordinating cell elongation and division, bacteria maintain their shape, support critical envelope functions, and orchestrate division. Regulatory and assembly systems have been implicated in these processes in some well-studied Gram-negative bacteria. However, we lack information on these processes and their conservation across the bacterial phylogeny. In R. sphaeroides and other α-proteobacteria, CenKR is an essential two-component system (TCS) that regulates the expression of genes known or predicted to function in cell envelope biosynthesis, elongation, and/or division. Here, we leverage unique features of CenKR to understand how increasing its activity impacts cell elongation/division and use antibiotics to identify how modulating the activity of this TCS leads to changes in cell morphology. Our results provide new insight into how CenKR activity controls the structure and function of the bacterial envelope, the localization of cell elongation and division machinery, and cellular processes in organisms with importance in health, host-microbe interactions, and biotechnology.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1991

Endoscopic measurement using radial metrology with digital correlation

Radial metrology combines standard optical measurement techniques with a unique panoramic annular lens (PAL) system to study material properties and deformations on the inner surfaces of the cavities found, for example, inside pipes, tubes, and boreholes. A PAL profilometer using speckle metrology is analyzed and the equations obtained from the analysis are used to calibrate the PAL profilometer when it is used to profile the inner surface of a cylindrical pipe and to measure the deformation of the pipe when it is subjected to diametral compression.

Matthys, Donald R.↗
DOE OSTI2019

Positron annihilation lifetime spectroscopy using fast scintillators and digital electronics

Positron Annihilation Lifetime Spectroscopy (PALS) is a non-destructive radiological technique widely used in material science studies. PALS typically relies on an analog coincidence measurement setup and allows the estimate of the positron lifetime in a material sample under investigation. The positron trapping at vacancies in the material results in an increased positron lifetime. In this work, we have developed and optimized a PALS experimental setup using organic scintillators, fast digitizers, and advanced pulse processing algorithms. We tested three pairs of different organic scintillators: EJ-309 liquid, EJ-276 newly developed plastic, and BC- 418 plastic, and optimized the data processing parameters for each pair separately. Our high-throughput data analysis method is based on single-pulse interpolation and a constant fraction discrimination (CFD) algorithm. The setup based on the BC-418 detector achieved the best time resolution of 198.3 ± 0.8 ps. We used such optimized setup to analyze two single-crystal quartz samples and found lifetimes of 161 ± 4 ps, 343 ± 12 ps and 1.34 ± 0.05 ns, in good agreement with the characteristic time constants of this material. The proposed experimental set up achieves a time resolution comparable to the minimum positron lifetime in quartz, which makes it possible to accurately characterize material vacancies by discriminating between the lifetimes of either the spin singlet or triplet states of positronium. The optimized data processing algorithms are relevant to all the applications where fast timing is important, such as nuclear medicine and radiation imaging

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Hydrated doped-BaZrO 3 proton conductors studied by positron annihilation lifetime spectroscopy

The study of defect chemistry for doped BaZrO 3 proton conductors is of particular interest because of defect interactions that can affect the proton conductivity of the material. Protons incorporated due to the material's hydration can be trapped by negatively charged immobile dopants, reducing proton mobility. The reduction of the proton conduction impedes using BaZrO 3 materials in energy conversion applications at intermediate temperatures (300°C – 600°C). The probing of proton trapping in doped BaZrO 3 is hindered by the limited availability of techniques sensitive to defect chemistries. In this work, we used positron annihilation lifetime spectroscopy (PALS) to study the defect chemistry of Y-doped and Sc-doped BaZrO 3 . Using a two-state positron trapping model we showed that PALS can be used to study the defect chemistry of hydrated dense proton conductors. Positron trapping rates and lifetimes were correlated with doping levels of the materials. Probability significance t-tests were carried out for PALS parameters to verify whether there are differences/similarities for various populations: non-doped/doped, level and type of doping, high temperature, and surface effects. Further, the results revealed that the initial doping generates a significant number of traps available for positrons. Doping in yttrium increased the positron trapping rate, while this effect was not observed with scandium. Low-temperature hydration affects specimens significantly inhibiting positron trapping at undoped BaZrO 3 material and highly doped specimens. Positronium formation in rough surface layers, and highly doped specimens was detected but does not exceed 1%.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Photo-Brook rearrangement of acyl silanes as a strategy for photoaffinity probe design

Photoaffinity labeling (PAL) is a powerful tool for the identification of non-covalent small molecule–protein interactions that are critical to drug discovery and medicinal chemistry, but this approach is limited to only a small subset of robust photocrosslinkers. The identification of new photoreactive motifs capable of covalent target capture is therefore highly desirable. Herein, we report the design, synthesis, and evaluation of a new class of PAL warheads based on the UV-triggered 1,2-photo-Brook rearrangement of acyl silanes, which hitherto have not been explored for PAL workflows. Irradiation of a series of probes in cell lysate revealed an iPr-substituted acyl silane with superior photolabeling and minimal thermal background labeling compared to other substituted acyl silanes. Further, small molecule (+)-JQ1- and rapamycin-derived iPr acyl silanes were shown to selectively label recombinant BRD4-BD1 and FKBP12, respectively, with minimal background. Together, these data highlight the untapped potential of acyl silanes as a novel, tunable scaffold for photoaffinity labeling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Monte Carlo Modeling and Design of Photon Energy Attenuation Layers for >10× Quantum Yield Enhancement in Si-Based Hard X-ray Detectors

High-energy (>20 keV) X-ray photon detection at high quantum yield, high spatial resolution, and short response time has long been an important area of study in physics. Scintillation is a prevalent method but limited in various ways. Directly detecting high-energy X-ray photons has been a challenge to this day, mainly due to low photon-to-photoelectron conversion efficiencies. Commercially available state-of-the-art Si direct detection products such as the Si charge-coupled device (CCD) are inefficient for >10 keV photons. Here, we present Monte Carlo simulation results and analyses to introduce a highly effective yet simple high-energy X-ray detection concept with significantly enhanced photon-to-electron conversion efficiencies composed of two layers: a top high-Z photon energy attenuation layer (PAL) and a bottom Si detector. We use the principle of photon energy down conversion, where high-energy X-ray photon energies are attenuated down to ≤10 keV via inelastic scattering suitable for efficient photoelectric absorption by Si. Our Monte Carlo simulation results demonstrate that a 10–30× increase in quantum yield can be achieved using PbTe PAL on Si, potentially advancing high-resolution, high-efficiency X-ray detection using PAL-enhanced Si CMOS image sensors.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Line-of-sight velocity and metallicity measurements of the palomar 5 tidal stream

We present Subaru/Faint Object Camera and Spectrograph and Keck/Deep Imaging Multi-Object Spectrometer medium-resolution spectroscopy of a tidally disrupting Milky Way (MW) globular cluster Palomar 5 (Pal 5) and its tidal stream. The observed fields are located to cover an angular extent of ∼17° along the stream, providing an opportunity to investigate a trend in line-of-sight velocities (V {sub los}) along the stream, which is essential to constrain its orbit and underlying gravitational potential of the MW’s dark matter halo. A spectral fitting technique is applied to the observed spectra to obtain stellar parameters and metallicities ([Fe/H]) of the target stars. The 19 stars most likely belonging to the central Pal 5 cluster have a mean V {sub los} of −58.1 ± 0.7 km s{sup −1} and metallicity [Fe/H] = −1.35 ± 0.06 dex, both of which are in good agreement with those derived in previous high-resolution spectroscopic studies. Assuming that the stream stars have the same [Fe/H] as the progenitor cluster, the derived [Fe/H] and V{sub los} values are used to estimate the possible V {sub los} range of the member stars at each location along the stream. Because of the heavy contamination of the field MW stars, the estimated V {sub los} range depends on prior assumptions about the stream’s V{sub los}, which highlights the importance of more definitely identifying the member stars using proper motion and chemical abundances to obtain unbiased information of V {sub los} in the outer part of the Pal 5 stream. The models for the gravitational potential of the MW’s dark matter halo that are compatible with the estimated V {sub los} range are discussed.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1991

A PARC system for terminal docking

A Panoramic viewing system for Automated Rendezvous and Capture (PARC) has been proposed as a visual information feedback system for terminal docking/berthing. The system relies on a unique Panoramic Annular Lens (PAL) which captures an image of its surroundings in real time. This paper describes the evolution of the PAL along with technical details of its imaging capabilities. Several examples are given of radial metrology, where PAL imaging systems are used to perform visual inspections and measurements. Digital image acquisition and processing techniques, used to interpret various features appearing in the images and to transform images for improved human viewing, are also included. These discussions are followed by a potential application for PARC involving berthing of active and passive mechanical assemblies associated with Space Station Freedom.

Gilbert, John A.↗
NASA NTRS1998

Nitrogen recycling during phenylpropanoid metabolism in sweet potato tubers

In the first step of the phenylpropanoid metabolic pathway, L-phenylalanine (L-Phe) is deaminated to form E-cinnamate, in a conversion catalyzed by phenylalanine ammonia-lyase (PAL; EC 4.3.1.5). The metabolic fate of the ammonium ion (NH4+) produced in this reaction was investigated in sweet potato (Ipomoea batatas) tuber discs. [15N]-Labeled substrates including L-Phe, in the presence or absence of specific enzyme inhibitors, were administered to sweet potato discs in light under aseptic conditions. 15N-Nuclear magnetic resonance spectroscopic analyses revealed that the 15NH4+ liberated during the PAL reaction is first incorporated into the amide nitrogen of L-glutamine (L-Gln) and then into L-glutamate (L-Glu). These results extend our previous observations in pine and potato that PAL-generated NH4+ is assimilated by the glutamine synthetase (GS; EC 6.3.1.2)/glutamate synthase (GOGAT; EC 1.4.1.13) pathway, with the NH4+ so formed ultimately being recycled back to L-Phe via L-Glu as aminoreceptor and donor.

Non-NASA Center↗
NASA NTRS2010

Utilization of Airborne and in Situ Data Obtained in SGP99, SMEX02, CLASIC and SMAPVEX08 Field Campaigns for SMAP Soil Moisture Algorithm Development and Validation

Field experiment data sets that include coincident remote sensing measurements and in situ sampling will be valuable in the development and validation of the soil moisture algorithms of the NASA's future SMAP (Soil Moisture Active and Passive) mission. This paper presents an overview of the field experiment data collected from SGP99, SMEX02, CLASIC and SMAPVEX08 campaigns. Common in these campaigns were observations of the airborne PALS (Passive and Active L- and S-band) instrument, which was developed to acquire radar and radiometer measurements at low frequencies. The combined set of the PALS measurements and ground truth obtained from all these campaigns was under study. The investigation shows that the data set contains a range of soil moisture values collected under a limited number of conditions. The quality of both PALS and ground truth data meets the needs of the SMAP algorithm development and validation. The data set has already made significant impact on the science behind SMAP mission. The areas where complementing of the data would be most beneficial are also discussed.

Soil moisture↗