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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

The Design of a Flexible, Interoperable Navigation Signal for Future Lunar Missions

The LunaNet Interoperability Specification (LNIS) is a set of standards currently under development by NASA, ESA, and JAXA, which define a common, interoperable set of services and interfaces for lunar communication and navigation. The LNIS includes specifications for the GNSS-like Augmented Forward Signal (AFS). The LANS (Lunar Augmented Navigation Service) will be comprised of Multiple LunaNet Service Provider (LNSP) nodes broadcasting the AFS, such as NASA’s LCRNS (Lunar Communications Relay and Navigation Systems), ESA’s Moonlight LCNS (Lunar Communication and Navigation Services) and the Japan LNSS (Lunar Navigation Satellite System). The LANS will provide a GNSS-like capability enabling orbiting and surface users in lunar space (such as Artemis) to estimate their position, velocity and time as described in Giordano et al., (2023). Initial capabilities will focus on providing service to the lunar South pole region. The specification of AFS defines two orthogonal signal components on a single carrier, with the in-phase component (AFS-I) being a lower-chip-rate data channel tailored for applications where low SWaP is critical (e.g., IoT devices or search and rescue), and the quadrature component (AFS-Q) being a high-chip-rate data-less pilot signal for high-precision, robust lunar navigation and positioning applications. An initial description of AFS was provided in the LNIS, (2023), and initial analysis results were shown in Dafesh, et al., (2024). In this work, we provide rationale for updates to the LNIS that define key aspects of the signal including the primary spreading code designs for the data and pilot channels, and a three-tiered overlay code approach for the pilot channel that provides flexible signal acquisition alternatives, rapid time dissemination and robust frame Sync. The paper also describes a robust data sync word that is designed to enable frame Sync. for low-SWaP receivers that only use the I channel, as well as a low-density parity check code (LDPC) data message encoding design and interleaving definition. The work further describes the impact of the updated AFS design in terms of improved acquisition performance, interference resistance, navigation message capabilities and rapid absolute time dissemination for users able to access clock and ephemeris data over an external network. The cross-correlation and synchronization performance of the AFS design is also compared to potential alternatives, further providing rationale for the final signal design configuration.

LANS↗
NASA NTRS2025

The Design of a Flexible, Interoperable Navigation Signal for Future Lunar Missions

The LunaNet Interoperability Specification (LNIS) is a set of standards currently under development by NASA, ESA, and JAXA, which define a common, interoperable set of services and interfaces for lunar communication and navigation. The LNIS includes specifications for the GNSS-like Augmented Forward Signal (AFS). The LANS (Lunar Augmented Navigation Service) will be comprised of Multiple LunaNet Service Provider (LNSP) nodes broadcasting the AFS, such as NASA’s LCRNS (Lunar Communications Relay and Navigation Systems), ESA’s Moonlight LCNS (Lunar Communication and Navigation Services) and the Japan LNSS (Lunar Navigation Satellite System). The LANS will provide a GNSS-like capability enabling orbiting and surface users in lunar space (such as Artemis) to estimate their position, velocity and time as described in Giordano et al., (2023). Initial capabilities will focus on providing service to the lunar South pole region. The specification of AFS defines two orthogonal signal components on a single carrier, with the in-phase component (AFS-I) being a lower-chip-rate data channel tailored for applications where low SWaP is critical (e.g., IoT devices or search and rescue), and the quadrature component (AFS-Q) being a high-chip-rate data-less pilot signal for high-precision, robust lunar navigation and positioning applications. An initial description of AFS was provided in the LNIS, (2023), and initial analysis results were shown in Dafesh, et al., (2024). In this work, we provide rationale for updates to the LNIS that define key aspects of the signal including the primary spreading code designs for the data and pilot channels, and a three-tiered overlay code approach for the pilot channel that provides flexible signal acquisition alternatives, rapid time dissemination and robust frame Sync. The paper also describes a robust data sync word that is designed to enable frame Sync. for low-SWaP receivers that only use the I channel, as well as a low-density parity check code (LDPC) data message encoding design and interleaving definition. The work further describes the impact of the updated AFS design in terms of improved acquisition performance, interference resistance, navigation message capabilities and rapid absolute time dissemination for users able to access clock and ephemeris data over an external network. The cross-correlation and synchronization performance of the AFS design is also compared to potential alternatives, further providing rationale for the final signal design configuration.

LunaNet↗
DOE OSTI2026

Evaluating Fracture Behavior of Bioinspired Alumina-YSZ Composites through Static and Dynamic Mechanical Testing

Ceramic materials are known for their high hardness and strength but are limited by low toughness and sudden failure. Inspired by the microstructure of dental enamel, which features undulating rods that promote crack deflection and energy absorption, architected specimens were designed and manufactured. A bespoke ball-on-ring (BoR) testing apparatus measured the static biaxial rupture strength of these bioinspired materials. Additionally, impact testing with spherical steel projectiles assessed their behavior under dynamic conditions. Monolithic alumina specimens were compared to architected alumina reinforced with yttria-stabilized zirconia (YSZ) rods produced via direct ink write 3D printing. BoR tests revealed that monolithic alumina had a Weibull modulus of 10.53 and a characteristic strength of 372.3 MPa, while the composite specimens showed a Weibull modulus of 5.46 and a characteristic strength of 213.3 MPa. Although the composite failed at lower stresses and projectile velocities, it exhibited notable crack deflection and fracture resistance, with cracks being effectively interrupted by the rod inclusions. The composite specimens also resulted in fewer and larger fragments upon impact. Finite element simulations confirmed the effectiveness of the rod structures in enhancing fracture resistance.

Bioinspired materials↗
DOE OSTI2021

Identification of Adaptive Fungal Pathogen Resistance Loci in Switchgrass (Final Report)

Switchgrass (Panicum virgatum) has great potential as a sustainable bioenergy and bioproducts feedstock. However, there are a number of challenges that must be overcome to achieve this goal. One of the most significant challenges to switchgrass productivity are fungal pathogens, especially rusts and smuts. The primary goals of our project were to characterize the distribution of fungal pathogens on switchgrass across central North America and to identify genetic loci that control resistance to those pathogens. The research was primarily conducted with large common garden plantings of a switchgrass, distributed along a latitudinal gradient from South Texas to South Dakota. By conducting this research simultaneously at 10 field locations, we were able establish the relative contributions of genes and the environment to pathogen resistance. Through this research, we identified multiple genomic regions (loci) that contribute to rust resistance and found that the effects of these loci on resistance were highly influenced by field site location. Our research revealed that most of the rust damage to switchgrass from Texas to the northern United States is caused by a single fungal species, Puccinia novopanici. Therefore, genetic variation within this species and/or local environmental conditions are responsible for the inconsistent efficacy of pathogen resistance loci. We are currently investigating these two non-mutually exclusive hypotheses. In addition to our studies of rust pathogens, we were able to identify resistance loci for the head smut fungal pathogen Tilletia maclaganii. The funding from this grant facilitated a collaboration with the DOE Joint Genome Institute to develop a reference genome for T. maclaganii. A reference genome will make population genetic studies of this smut fungus possible, which in turn will facilitate the development of strategies to mitigate its impact. Overall, the funded research has greatly advanced our understanding of the genetic basis of fungal pathogen resistance switchgrass. This knowledge will help facilitate the breeding of more resistant cultivars and thus, increase the productivity of swichgrass generally.

09 BIOMASS FUELS↗
NASA NTRS2008

The Development of a Remote Sensor System and Decision Support Systems Architecture to Monitor Resistance Development in Transgenic Crops

The United States Environmental Protection Agency (EPA) has declared that "significant benefits accrue to growers, the public, and the environment" from the use of transgenic pesticidal crops due to reductions in pesticide usage for crop pest management. Large increases in the global use of transgenic pesticidal crops has reduced the amounts of broad spectrum pesticides used to manage pest populations, improved yield and reduced the environmental impact of crop management. A significant threat to the continued use of this technology is the evolution of resistance in insect pest populations to the insecticidal Bt toxins expressed by the plants. Management of transgenic pesticidal crops with an emphasis on conservation of Bt toxicity in field populations of insect pests is important to the future of sustainable agriculture. A vital component of this transgenic pesticidal crop management is establishing the proof of concept basic understanding, situational awareness, and monitoring and decision support system tools for more than 133650 square kilometers (33 million acres) of bio-engineered corn and cotton for development of insect resistance . Early and recent joint NASA, US EPA and ITD remote imagery flights and ground based field experiments have provided very promising research results that will potentially address future requirements for crop management capabilities.

Cacas, Joseph↗
NASA NTRS2005

Effects of an Early-Time Impact Generated Vapor Blast in the Martian Atmosphere: Formation of High-Latitude Pedestal Craters

Following impact, vapor expansion creates an intense airblast that interacts with the ambient atmosphere. The resulting hemi-spherical shock wave leaves a signature on the surface that is dependent on initial atmospheric and surface conditions. Here we propose that the formation of pedestal craters (craters surrounded by an erosion-resistant pedestal) may be a direct consequence of extreme winds and elevated temperatures generated by such an impact-induced atmospheric blast. Pedestal craters, first recognized in Mariner 9 data, are a unique feature on Mars and likely a signature of near-surface volatiles. They are found at high latitudes (small pedestals, Amazonian to Late Hesperian in age) and in thick equatorial mantling deposits (larger pedestals, early Hesperian to Noachian in age). Previously suggested mechanisms for pedestal crater formation (e.g., wind: ejecta curtain vortices or vapor blast; and ejecta dust: armoring) do not provide a complete picture. The clear evidence for near-surface volatiles at high latitudes requires a re-evaluation of these alternative models. The results presented here suggest that a combined atmospheric blast/thermal model provides a plausible formation hypothesis.

Wrobel, K. E.↗
NASA NTRS2012

Archway for Radiation and Micrometeorite Occurrence Resistance

The environmental conditions of the Moon require mitigation if a long-term human presence is to be achieved for extended periods of time. Radiation, micrometeoroid impacts, high-velocity debris, and thermal cycling represent threats to crew, equipment, and facilities. For decades, local regolith has been suggested as a candidate material to use in the construction of protective barriers. A thickness of roughly 3m is sufficient protection from both direct and secondary radiation from cosmic rays and solar protons; this thickness is sufficient to reduce radiation exposure even during solar flares. NASA has previously identified a need for innovations that will support lunar habitats using lightweight structures because the reduction of structural mass translates directly into additional up and down mass capability that would facilitate additional logistics capacity and increased science return for all mission phases. The development of non-pressurized primary structures that have synergy with the development of pressurized structures is also of interest. The use of indigenous or in situ materials is also a well-known and active area of research that could drastically improve the practicality of human exploration beyond low-Earth orbit. The Archway for Radiation and Micrometeorite Occurrence Resistance (ARMOR) concept is a new, multifunctional structure that acts as radiation shielding and micrometeorite impact shielding for long-duration lunar surface protection of humans and equipment. ARMOR uses a combination of native regolith and a deployed membrane jacket to yield a multifunctional structure. ARMOR is a robust and modular system that can be autonomously assembled on-site prior to the first human surface arrival. The system provides protection by holding a sufficiently thick (3 m) archshaped shell of local regolith around a central cavity. The regolith is held in shape by an arch-shaped jacket made of strong but deployable material. No regolith processing is required. During the regolith filling process, an inflatable structure under the arch supports the mass of the regolith, but once regolith filling is complete the catenary arch formed by the regolith and the jacket becomes self-supporting and the inflatable can be deflated and removed. When complete, habitat modules and equipment can be moved into the protected cavity under the arch. ARMOR is a nearterm system that would provide a reliable and robust lightweight structure technology to support large lunar habitats, drastically lower launch mass, and improve efficient volume use, reducing launch costs.

Giersch, Louis R.↗
DOE OSTI2025

Chromium versus Aluminum: Impact of Nickel Alloy Composition and Interfacial Kinetics on High-Temperature Passivating Oxide Formation

High-temperature corrosion resistance depends critically on the formation of a passivating surface oxide, which is highly sensitive to alloy composition and structure. Such details often elude experimental investigation, and simplified analytical models fail to provide a truly chemical view of passivating oxide evolution. Here, we explicitly compare the fundamental chemistry of Cr and Al as prototypical passivating elements in Ni alloys by directly simulating competing reaction and diffusion processes within the oxide film using kinetic Monte Carlo and density functional theory. We find that the origin and expression of passivating behavior during early-stage thermal oxidation are qualitatively different between the two alloy systems. Ni–Cr alloys feature a sudden onset of passivation associated with a sharp phase transition upon Cr enrichment that directly couples oxidation kinetics to phase transformation behavior. In contrast, Ni–Al alloys display more continuous oxide phase variation with Al enrichment, ultimately resulting in a lower composition threshold for passivation and a thinner passivating layer. In addition, we elucidate the nonobvious role of metal exchange within the alloy near the oxide boundary, which fundamentally alters film composition and passivating behavior. Furthermore, our results have key implications for engineering improved corrosion-resistant alloys, both in terms of compositional variation and processing.

Alloys↗
NASA NTRS2010

Overview of the Development of the Temporary Sleep Station Hygiene Liner Aboard the International Space Station

Since the beginning of manned operations aboard the International Space Station (ISS), the crew had performed hygiene activities within the aisle way (the habitable volume, not including the sleep areas) of the ISS. The Crew used wet towels, re-hydrated body soap, and "no-rinse" shampoo to cleanse themselves amongst the stowage and systems hardware, referred to as "racks", even without a designated area to dry the wet items. Performing hygiene in this manner became an accepted method; no isolated location was available to the Crew. After several years of hygiene operations, some of the fabric-covered racks began to grow biological material (generically described as mold) and soon became a Crew health concern. Hygiene has one of the strongest impacts on Crew morale, and mandating changes to the Crew routine would have been met with strong resistance. The answer to the conundrum was to develop a liner to be placed within the Temporary Sleep Station (TeSS), one of the Crew s sleeping racks. This liner provided the Crew a means to perform hygiene activities within a private, enclosed area that also significantly decreased the potential to grow mold. This paper will describe the development of the TeSS Hygiene Liner, its impacts on the ISS and Crew, as well as its contribution to hygiene activities used in space today.

Reid, Ethan A.↗
DOE OSTI2025

Substituent size versus metal binding of inhibitors with variants of influenza endonuclease

The influenza virus causes a significant burden of illness each year. Although vaccination is the most effective method to prevent seasonal influenza infection, viral escape mechanisms make vaccine composition difficult to predict. Antivirals are crucial for decreasing rates of morbidity and mortality from influenza viral infection. The newest anti-influenza drugs target the RNA-dependent RNA polymerase acidic N-terminal (PA N ) endonuclease, a critical component of influenza viral replication machinery. This study examines the structure of inhibitors of PAN that utilize a hydroxypyridinone-based metal-binding pharmacophore (MBP). Specifically, this report explores how the size of substituent groups impacts the binding conformation and affinity of a series of compounds against both wild-type (WT) and resistance mutant strains, I38T and E23K. Co-crystal structures revealed that the distance between compounds and enzyme residue 38 was conserved to maintain strong interactions, resulting in deviations from ideal coordination geometries at the active site metal centers. This suggests the interactions with residue 38 with each compound is important and can impact inhibitor potency as a consequence of distortions in the metal binding geometry of the compounds.

Endonuclease↗
DOE OSTI2023

PRO-X Parallelization Study

The proliferation resistance optimization (PRO-X) program is actively supporting the design of nuclear systems by developing a framework to both optimize the fuel cycle infrastructure for nuclear reactor (including both advanced reactors (ARs) and research reactors (RRs)) and minimize the potential for production of weapons-usable nuclear material (Figure 1). One area of interest is in the impact a modular approach to bulk handling fuel cycle facilities could have on meeting safeguards requirements to identify future areas of growth within the proliferation resistance space. This study evaluates how changing the number of streams within a fuel cycle facility could impact a facilities ability to meet both domestic and international safeguards requirements.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Stress corrosion cracking mechanism of cold spray coating on a galvanically similar substrate

Here, the chloride-induced stress corrosion cracking (CISCC) mechanism of cold spray (CS) coating on a galvanically similar substrate is investigated. Arc welded 304L stainless steel (SS) specimens are loaded into four-point bend fixtures, cold sprayed with 304L SS, then immersed in boiling MgCl 2 . Interconnected porosity forms through crevice corrosion along CS splat boundaries, allowing corrosive species to penetrate through the CS layer. Nevertheless, the substrate is resistant to CISCC likely because of compressive stress introduced by peening during CS particle impacts. These findings underscore the importance of residual stress in the environmental degradation of CS coatings or repairs of engineering structures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Chasing the multi-modal plasma response in MAST-U

Abstract Achieving edge localized modes (ELMs) suppression in spherical tokamaks by applying resonant magnetic perturbations (RMPs) has proven challenging. The poloidal spectrum of the applied RMP is a key parameter that has an impact on the capability to mitigate and eventually suppress ELMs. In this work the resistive magnetohydrodynamic code MARS-F (Liu et al 2000 Phys. Plasmas 7 3681) is used to evaluate the possibility of directly measuring the plasma response in MAST-U, and particularly its variation as function of the applied poloidal spectrum, in order to guide the experimental validation of the predicted best RMP configuration for ELM suppression. Toroidal mode number n = 2 RMP is considered to minimize the presence of sidebands, and to avoid the deleterious core coupling of n = 1. Singular Value Decomposition is used to highlight linearly independent structures in the simulated magnetic 3D fields and how those structures can be measured at the wall where the magnetic sensors are located. Alternative ways to measure the multimodal plasma response and how they can be used to infer the best RMP configuration to achieve ELM suppression are also presented, including the plasma displacement and the 3D footprints at the divertor plates.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2002

Persistent Ehrlichia chaffeensis infection occurs in the absence of functional major histocompatibility complex class II genes

Human monocytic ehrlichiosis is an emerging tick-borne disease caused by the rickettsia Ehrlichia chaffeensis. We investigated the impact of two genes that control macrophage and T-cell function on murine resistance to E. chaffeensis. Congenic pairs of wild-type and toll-like receptor 4 (tlr4)- or major histocompatibility complex class II (MHC-II)-deficient mice were used for these studies. Wild-type mice cleared the infection within 2 weeks, and the response included macrophage activation and the synthesis of E. chaffeensis-specific Th1-type immunoglobulin G response. The absence of a functional tlr4 gene depressed nitric oxide and interleukin 6 secretion by macrophages and resulted in short-term persistent infections for > or =30 days. In the absence of MHC-II alleles, E. chaffeensis infections persisted throughout the entire 3-month evaluation period. Together, these data suggest that macrophage activation and cell-mediated immunity, orchestrated by CD4(+) T cells, are critical for conferring resistance to E. chaffeensis.

NASA Discipline Cell Biology↗
NASA NTRS1954

Investigation of the Hydrodynamic Characteristics of the Panto-Base Chase C-123 Airplane

An investigation of a 1/14-scale dynamically similar model of a panto-base version of the Chase C-123 airplane was conducted to evaluate the hydrodynamic characteristics of the airplane. The resistance, longitudinal stability, and spray patterns during take-off and general behavior in calm- and rough-water landings were determined. Brief calm-water tests were made to compare the initial vertical impact accelerations of the model with and without hydro-skis. Take-off stability was satisfactory for calm-water operation. A ratio of gross load to maximum resistance of 3,6 was obtained. Heavy spray reached the propellers only during ski emergence. The landing behavior in calm water and in waves 3 feet by 150 feet (full scale) was satisfactory for a normal range of trim angles. Initial impacts in calmwater landings resulted in vertical accelerations of about 2 1/2 with the hydro-skis installed and about 4g with the hydro-skis removed,

Thompson, William C.↗
DOE OSTI2023

Co-regulation of water and energy in the spatial heterogeneity of drought resistance and resilience

Vegetation resistance and resilience to drought are linked to the stability of terrestrial ecosystems under climate change. However, the factors driving the spatial heterogeneity in drought resistance and resilience remain poorly understood. In the study, we utilized multiple satellite-derived vegetation indices to calculate and analyze changes in drought resistance and resilience across various biomes worldwide. Results indicated that drought resistance showed a significant increase with the increase in water availability, but no significant relationship was observed between drought resistance and energy. In contrast, drought resilience exhibited a significant increase with an increase in energy rather than in water. Furthermore, a negative correlation was observed between drought resistance and resilience across different biomes worldwide, indicating a trade-off between resistance and resilience. However, the strength of the negative correlation varied based on water and energy conditions. These findings provide compelling evidence that water and energy co-regulated the spatial heterogeneity in drought resistance and resilience across the globe. The robust linear relationship between drought resistance and resilience and available water and energy demonstrated in our study is critical to accurately predicting and assessing the impact of climate change on vegetation growth and terrestrial carbon cycling in the future.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Structural genomics of bacterial drug targets: Application of a high-throughput pipeline to solve 58 protein structures from pathogenic and related bacteria

Antibiotic resistance remains a leading cause of severe infections worldwide. Small changes in protein sequence can impact antibiotic efficacy. Here, we report deposition of 58 X-ray crystal structures of bacterial proteins that are known targets for antibiotics, which expands knowledge of structural variation to support future antibiotic discovery or modifications.

PDB↗