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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

CO2 Washout Testing of the REI and EM-ACES Space Suits

Requirements for using a space suit during ground testing include providing adequate carbon dioxide (CO2) washout for the suited subject. Acute CO2 exposure can lead to symptoms including headache, dyspnea, lethargy and eventually unconsciousness or even death. Symptoms depend on several factors including partial pressure of CO2 (ppCO2), duration of exposure, metabolic rate of the subject and physiological differences between subjects. The objective of this test was to characterize inspired oronasal ppCO2 in the Rear Entry I-Suit (REI) and the Enhanced Mobility Advanced Crew Escape Suit (EM-ACES) across a range of workloads and flow rates for which ground testing is nominally performed. Three subjects were tested in each suit. In all but one case, each subject performed the test twice to allow for comparison between tests. Suit pressure was maintained at 4.3 psid. Subjects wore the suit while resting, performing arm ergometry, and walking on a treadmill to generate metabolic workloads of approximately 500 to 3000 BTU/hr. Supply airflow was varied at 6, 5 and 4 actual cubic feet per minute (ACFM) at each workload. Subjects wore an oronasal mask with an open port in front of the mouth and were allowed to breathe freely. Oronasal ppCO2 was monitored real-time via gas analyzers with sampling tubes connected to the oronasal mask. Metabolic rate was calculated from the total CO2 production measured by an additional gas analyzer at the air outlet from the suit. Real-time metabolic rate was used to adjust the arm ergometer or treadmill workload to meet target metabolic rates. In both suits, inspired CO2 was primarily affected by the metabolic rate of the subject, with increased metabolic rate resulting in increased inspired ppCO2. Suit flow rate also affected inspired ppCO2, with decreased flow causing small increases in inspired ppCO2. The effect of flow was more evident at metabolic rates greater than or equal to 2000 BTU/hr. Results were consistent between suits, with the EM-ACES demonstrating slightly better CO2 washout than the REI suit, but not statistically significant. Regression equations were developed for each suit to predict the mean inspired ppCO2 as a function of metabolic rate and suit flow rate. This paper provides detailed descriptions of the test hardware, methodology and results, as well as implications for future ground testing in the REI and EM-ACES.

Mitchell, Kate↗
NASA NTRS2012

CO2 Washout Testing of the REI and EM-ACES Space Suits

When a space suit is used during ground testing, adequate carbon dioxide (CO2) washout must be provided for the suited subject. Symptoms of acute CO2 exposure depend on partial pressure of CO2 (ppCO2), metabolic rate of the subject, and other factors. This test was done to characterize inspired oronasal ppCO2 in the Rear Entry I-Suit (REI) and the Enhanced Mobility Advanced Crew Escape Suit (EM-ACES) for a range of workloads and flow rates for which ground testing is nominally performed. Three subjects were tested in each suit. In all but one case, each subject performed the test twice. Suit pressure was maintained at 4.3 psid. Subjects wore the suit while resting, performing arm ergometry, and walking on a treadmill to generate metabolic workloads of about 500 to 3000 BTU/hr. Supply airflow was varied between 6, 5, and 4 actual cubic feet per minute (ACFM) at each workload. Subjects wore an oronasal mask with an open port in front of the mouth and were allowed to breathe freely. Oronasal ppCO2 was monitored in real time by gas analyzers with sampling tubes connected to the mask. Metabolic rate was calculated from the total CO2 production measured by an additional gas analyzer at the suit air outlet. Real-time metabolic rate was used to adjust the arm ergometer or treadmill workload to meet target metabolic rates. In both suits, inspired CO2 was affected mainly by the metabolic rate of the subject: increased metabolic rate significantly (P < 0.05) increased inspired ppCO2. Decreased air flow caused small increases in inspired ppCO2. The effect of flow was more evident at metabolic rates . 2000 BTU/hr. CO2 washout values of the EM-ACES were slightly but not significantly better than those of the REI suit. Regression equations were developed for each suit to predict the mean inspired ppCO2 as a function of metabolic rate and suit flow rate. This paper provides detailed descriptions of the test hardware, methodology, and results as well as implications for future ground testing in the REI-suit and EM-ACES.

Mitchell, Kathryn C.↗
NASA NTRS2018

Quality Assurance Surveillance Tool Designed for SLS EM-1 Certificate of Flight Readiness

Exploration Mission-1 (EM-1) is an uncrewed mission that is launching on the Space Launch System (SLS) Block 1 vehicle. This is a critical flight test for the agency's human deep space exploration goals. Exploration Ground Systems (EGS) Quality (SA-F2) is responsible for providing Quality Assurance Surveillance Plans (QASPs) for NASA contracts and facilities. A QASP assures products and services are provided to EGS in accordance with the contract requirements. In order to encapsulate the multiple KSC Safety and Mission Assurance surveillance and audit activities that need to be accomplished specifically for EM-1 Certificate of Flight Reediness (CoFR), a QASP tool needed to be implemented. This tool would be able to intuitively track Work Authorization Documents (WADs) under development by Test Operations Support Contract (TOSC), reviewed and accepted WADs, Government Mandatory Inspection Points (GMIPs), Nonconformances (NCs), Material Review Board (MRB) Status, Corrective Actions, Alterations, Deviations, and Waivers for flight hardware and Ground Support Equipment (GSE). This would help ensure that all SLS EM-1 flight hardware and related GSE surveillances and requirements are being recognized and completed with zero constraints identified for the mission.

Morris, Patrick↗
NASA NTRSDate not supplied

Development and Initial Validation of HFBP-EM Short-Form Surveys

The Human Factors and Behavioral Performance Exploration Measures (HFBP-EM) suite includes self-report surveys designed to assess Behavioral Medicine (BMed) and Team risks for future exploration class missions. Survey data was collected during the Human Exploration Research Analog (HERA) Campaign 4 (C4), HERA Campaign 5 (C5), and during SIRIUS19 missions in the Russian Ground Based Experiment Complex, NEK. Crew time in spaceflight analogs and in spaceflight is typically limited. Extensive self-report surveys can be a significant burden to participants and are not operationally acceptable for spaceflight. The purpose of this project was to comprehensively assess the reliability and validity of the standard-length HFBP-EM surveys, identify acceptable short forms to administer during HERA C6, examine initial validation evidence for the proposed short form measures, and identify key measurement gaps in HFBP-EM coverage. In this presentation, we will report reliability and validity metrics of standard form data, describe the proposed new short forms, and present initial psychometric analyses supporting the use of these short forms.

S T Bell↗
DOE OSTI2024

Likelihood-based interactive local docking into cryo-EM maps in ChimeraX

The interpretation of cryo-EM maps often includes the docking of known or predicted structures of the components, which is particularly useful when the map resolution is worse than 4 Å. Although it can be effective to search the entire map to find the best placement of a component, the process can be slow when the maps are large. However, frequently there is a well-founded hypothesis about where particular components are located. In such cases, a local search using a map subvolume will be much faster because the search volume is smaller, and more sensitive because optimizing the search volume for the rotation-search step enhances the signal to noise. A Fourier-space likelihood-based local search approach, based on the previously published em_placement software, has been implemented in the new emplace_local program. Tests confirm that the local search approach enhances the speed and sensitivity of the computations. An interactive graphical interface in the ChimeraX molecular-graphics program provides a convenient way to set up and evaluate docking calculations, particularly in defining the part of the map into which the components should be placed.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

CryoDRGN-AI: neural ab initio reconstruction of challenging cryo-EM and cryo-ET datasets

Proteins and other biomolecules form dynamic macromolecular machines that are tightly orchestrated to move, bind, and perform chemistry. Cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET) can access the intrinsic heterogeneity of these complexes and are therefore key tools for understanding their function. However, 3D reconstruction of the collected imaging data presents a challenging computational problem, especially without any starting information, a setting termed ab initio reconstruction. Here, in this study, we introduce cryoDRGN-AI, a method leveraging an expressive neural representation and combining an exhaustive search strategy with gradient-based optimization to process challenging heterogeneous datasets. Using cryoDRGN-AI, we reveal new conformational states in large datasets, reconstruct previously unresolved motions from unfiltered datasets, and demonstrate ab initio reconstruction of biomolecular complexes from in situ data. With this expressive and scalable model for structure determination, we hope to unlock the full potential of cryo-EM and cryo-ET as a high-throughput tool for structural biology and discovery.

Levy, Axel [Stanford Univ., CA (United States); SL↗
DOE OSTI2025

Targeted seed EMS mutagenesis reveals a basic helix–loop–helix transcription factor underlying male sterility in sorghum

Abstract Forward genetic screens of mutant populations are fundamental for functional genomics studies. However, isolating independent mutant alleles to molecularly identify causal genes is challenging in species recalcitrant to genetic manipulation. Here, we demonstrate that classic seed ethyl methanesulfonate (EMS) mutagenesis coupled with genome sequencing can overcome this limitation in sorghum. We used this method to generate new mutant alleles of sorghum MALE STERILE 8 (MS8) and identified the causal locus for the ms8 phenotype as Sobic.004G270900, which encodes the sorghum ortholog of maize bhlh122, a basic helix–loop–helix (bHLH) transcription factor required for male fertility in maize. Bulked segregant analysis mapped ms8-1 to a region on chromosome 4 containing Sobic.004G270900. Seeds from heterozygous MS8/ms8-1 plants were mutagenized and screened for chimeric inflorescences containing sectors with white, sterile anthers resembling the ms8-1 homozygous phenotype. DNA sequencing of sterile and fertile sectors from a single chimeric inflorescence revealed two mutations in Sobic.004G270900 within the sterile sector, but not the fertile sector. Isolation of this loss-of-function allele (ms8-2) established Sobic.004G270900 as the causative locus for male sterility in the ms8 mutant. We generated additional alleles of MS8 in a different genetic background using CRISPR/Cas9-based gene editing, where deletions in Sobic.004G270900 also resulted in male sterility. Our work identified a gene underlying male sterility in sorghum and provides a novel and straightforward genetic tool for researchers who lack access to advanced transformation facilities to validate gene candidates. Unlike gene editing, no prior knowledge of candidate genes is required for targeted seed EMS mutagenesis to aid identification of causal loci.

Genetics & Heredity↗
NASA NTRS1981

A laboratory experiment on EM backscatter from Farley-Buneman and gradient drift waves

Results of laboratory experiment on Bragg backscatter of 3-cm microwaves by turbulent waves driven by the Farley-Buneman and gradient drift instabilities are reported. It is noted that the study is the third in a series of laboratory experiments performed to test, under controlled conditions, prevalent ideas on EM scattering by equatorial and high-latitude ionospheric waves and irregularities. It is shown through separate backscattering from fast and slow ion beam modes that a beam of EM radiation actually provides, in backscatter, information on the spectral content of the scattering medium.

Alport, M. J.↗
NASA NTRS1982

Mixture densities, maximum likelihood, and the EM algorithm

The problem of estimating the parameters which determine a mixture density is reviewed as well as maximum likelihood estimation for it. A particular iterative procedure for numerically approximating maximum likelihood estimates for mixture density problems is considered. This EM algorithm, is a specialization to the mixture density context of a general algorithm of the same name used to approximate maximum likelihood estimates for incomplete data problems. The formulation and theoretical and practical properties of the EM algorithm for mixture densities are discussed focussing in particular on mixtures of densities from exponential families.

Redner, R. A.↗
NASA NTRS1988

A selective modal scheme for the analysis of EM coupling into or radiation from large open-ended waveguides

A selective modal scheme is proposed to efficiently analyze the problem of high-frequency (HF) electromagnetic (EM) coupling/penetration into or radiation from open-ended waveguides. This scheme is based on the phenomenon that at sufficiently high frequencies, the modes which contribute most significantly to the fields coupled into the waveguide are those whose modal ray directions are most nearly parallel to the incident-wave direction. This concept is illustrated by calculating the EM radiation and backscattering from open-ended parallel-plate, rectangular, circular, and sectoral waveguide geometries. The calculations use the usual geometrical optics, aperture field, and Ufimtsev edge current techniques. Also included are some measured results which further verify the accuracy of the above computations.

Altintas, Ayhan↗
NASA NTRS1991

Analytical prediction of EM scattering by complex obstacles within electrically large open cavities

An analytical technique is described for predicting the electromagnetic (EM) scattering by complex obstacles within electrically large open waveguide cavities. This topic is of relevance to EM scattering and EMC type applications. A general open ended waveguide cavity is illustrated and is assumed to be relatively arbitrarily shaped, and the open front end of the cavity is illuminated by an arbitrarily polarized external plane wave field. The interior obstacle is assumed to be located within the cavity near the back end, and it generally contributes significantly to the fields scattered into the exterior by the entire cavity configuration. The present scattering analysis is restricted to within approximately 70 degs from boresight with respect to the open front end; outside of this region, the scattering by the external features of the cavity are generally more significant than from the interior of the cavity. The scattering analysis is composed of two main parts. One analysis is of the coupling of the incident plane wave field, via the open front end using the high frequency ray or beam shooting methods. The other analysis deals with separately obtaining the plane wave scattering characteristics of the interior obstacle. Thus the present analysis represents a hybrid combination of an asymptotic high frequency ray/beam method for tracking the fields through the cavity, together with any suitable method for obtaining a plane wave characterization of the interior obstacle.

Pathak, Prabhakar H.↗
NASA NTRS1990

Pre-flight risk assessment in emergency medical service (EMS) helicopters

A preflight risk assessment system (SAFE) was developed at NASA-Ames Research Center for civil EMS operations to assist pilots in making a decision objectively to accept or decline a mission. The ability of the SAFE system to predict risk profiles was examined at an EMS operator. Results of this field study showed that the usefulness of SAFE was largely dependent on the type of mission flown.

Shively, Robert J.↗
NASA NTRS1993

A reciprocity formulation for the EM scattering by an obstacle within a large open cavity

A formulation based on a generalized reciprocity theorem is developed for analyzing the external high frequency EM scattering by a complex obstacle inside a relatively arbitrary open-ended waveguide cavity when it is illuminated by an external source. This formulation is also extended to include EM fields whose time dependence may be nonperiodic. A significant advantage of this formulation is that it allows one to break up the analysis into two independent parts; one deals with the waveguide cavity shape alone and the other with the obstacle alone. The external scattered field produced by the obstacle (in the presence of the waveguide cavity structure) is given in terms of a generalized reciprocity integral over a surface S(T) corresponding to the interior waveguide cavity cross section located conveniently but sufficiently close to the obstacle. Furthermore, the fields coupled into the cavity from the source in the exterior region generally need to propagate only one-way via the open front end (which is directly illuminated) to the interior surface S(T) in this approach, and not back, in order to find the external field scattered by the obstacle.

Pathak, Prabhakar H.↗
NASA NTRS1994

Superconducting Electromagnetic Suspension (EMS) system for Grumman Maglev concept

The Grumman developed Electromagnetic Suspension (EMS) Maglev system has the following key characteristics: a large operating airgap--40 mm; levitation at all speeds; both high speed and low speed applications; no deleterious effects on SC coils at low vehicle speeds; low magnetic field at the SC coil--less than 0.35 T; no need to use non-magnetic/non-metallic rebar in the guideway structure; low magnetic field in passenger cabin--approximately 1 G; low forces on the SC coil; employs state-of-the-art NbTi wire; no need for an active magnet quench protection system; and lower weight than a magnet system with copper coils. The EMS Maglev described in this paper does not require development of any new technologies. The system could be built with the existing SC magnet technology.

Kalsi, Swarn S.↗
NASA NTRS1994

EM-ANIMATE: A Computer Program for Displaying and Animating Electromagnetic Near-Field and Surface-Current Solutions: Video Supplement to NASA Technical Memorandum 4539

In this video, several examples of electromagnetic field and surface-current animation sequences are shown to demonstrate the visualization capabilities of the EM-ANIMATE computer program. These examples show the animation of total and scattered electric near fields from test bodies of a flat plate, a corner reflector, and a sphere. These test cases show the electric-field behavior caused by different scattering mechanisms through the animation of electromagnetic data from the EM-ANIMATE routine.

Hom, Kam W.↗
NASA NTRS2011

NASA EM Followup of LIGO-Virgo Candidate Events

We present a strategy for a follow-up of LIGO-Virgo candidate events using offline survey data from several NASA high-energy photon instruments aboard RXTE, Swift, and Fermi. Time and sky-location information provided by the GW trigger allows for a targeted search for prompt and afterglow EM signals. In doing so, we expect to be sensitive to signals which are too weak to be publicly reported as astrophysical EM events.

Blackburn, Lindy L.↗
NASA NTRS2014

Trajectory Design Analysis over the Lunar Nodal Cycle for the Multi-Purpose Crew Vehicle (MPCV) Exploration Mission 2 (EM-2)

The first crewed mission, Exploration Mission 2 (EM-2), for the MPCV Orion spacecraft is scheduled for August 2021, and its current mission is to orbit the Moon in a highly elliptical lunar orbit for 3 days. A 21-year scan was performed to identify feasible missions that satisfy the propulsive capabilities of the Interim Cryogenic Propulsion Stage (ICPS) and MPCV Service Module (SM). The mission is divided into 4 phases: (1) a lunar free return trajectory, (2) a hybrid maneuver, during the translunar coast, to lower the approach perilune altitude to 100 km, (3) lunar orbit insertion into a 100 x 10,000 km orbit, and (4) lunar orbit loiter and Earth return to a splashdown off the coast of Southern California. Trajectory data was collected for all feasible missions and converted to information that influence different subsystems including propulsion, power, thermal, communications, and mission operations. The complete 21-year scan data shows seasonal effects that are due to the Earth-Moon geometry and the initial Earth parking orbit. The data and information is also useful to identify mission opportunities around the current planned launch date for EM-2.

Gutkowski, Jeffrey P.↗
NASA NTRS2018

Orion Heat Shield Manufacturing Producibility Improvements for the EM-1 Flight Test Program

This paper describes how the ORION program is incorporating improvements in the heat shield design and manufacturing processes reducing programmatic risk and ensuring crew safety in support of NASA's Exploration missions. The approach for the EFT-1 heat shield utilized a low risk Apollo heritage design and manufacturing process using an Avcoat TPS ablator with a honeycomb substrate to provide a one piece heat shield to meet the mission re-entry heating environments. The EM-1 mission will have additional flight systems installed to fly to the moon and return to Earth. Heat shield design and producibility improvements have been incorporated in the EM-1 vehicle to meet deep space mission requirements. The design continues to use the Avcoat material, but in a block configuration to enable improvements in consistant and repeatable application processes using tile bonding experience developed on the Space Shuttle Transportation System Program.

Producibility↗