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All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Design and Performance of the Astro-E/XRS Microcalorimeter Array and Anti-Coincidence Detector

The XRS instrument has an array of 32 micro-calorimeters at the focal plane. These calorimeters consist of ion-implanted silicon thermistors and HgTe thermalizing x-ray absorbers. These devices have demonstrated a resolution of 9 eV at 3 keV and 11 eV at 6 keV. We will discuss the basic physical parameters of this array, including the array layout, thermal conductance of the link to the heat sink, operating temperature, thermistor size, absorber choice, and means of attaching the absorber to the thermistor bearing element. We will present representative performance data, though a more detailed presentation of the results of the instrument calibration is presented elsewhere in these proceedings. A silicon ionization detector is located behind the calorimeter array and serves to reject events due to cosmic rays. We will briefly describe this anti-coincidence detector and its performance in conjunction with the array.

Stahle, C. K.↗
NASA NTRS1999

Sensitized Liquid Hydrazine Detonation Studies

Vapor-phase hydrazine (N2H4) is known to be very sensitive to detonation while liquid hydrazine is very insensitive to detonation, theoretically requiring extremely high pressures to induce initiation. A review of literature on solid and liquid explosives shows that when pure explosive substances are infiltrated with gas cavities, voids, and/or different phase contaminants, the energy or shock pressure necessary to induce detonation can decrease by an order of magnitude. Tests were conducted with liquid hydrazine in a modified card-gap configuration. Sensitization was attempted by bubbling helium gas through and/or suspending ceramic microspheres in the liquid. The hydrazine was subjected to the shock pressure from a 2 lb (0.9 kg) Composition C-4 explosive charge. The hydrazine was contained in a 4 in. (10.2 cm) diameter stainless steel cylinder with a 122 in(sup 3) (2 L) volume and sealed with a polyethylene cap. Blast pressures from the events were recorded by 63 high speed pressure transducers located on three radial legs extending from 4 to 115 ft (1.2 to 35.1 in) from ground zero. Comparison of the neat hydrazine and water baseline tests with the "sensitized" hydrazine tests indicates the liquid hydrazine did not detonate under these conditions.

Rathgeber, K. A.↗
NASA NTRS1999

The Transport and Fate of Particulate Material in a Shallow, Turbid Estuary: Seasonal and Decadal Characteristics from 7-Be and 210-Pb Techniques

Seasonal and long-term sediment transport characteristics were examined using surficial sediment 7-Be inventories and the down core distribution of excess 210-Pb. Data were collected in the Barataria Basin, LA over the fifteen month period from September 1995 to January 1997. Seasonal sediment transport rates based on 7-Be inventories ranged from -1.6E3 to 1.42E4 g/m2/yr, whereas decadal sediment burial rates based on excess 210-Pb ranged from 3.83E2 to 2.00E3 g/m2/yr, respectively. Seasonal transport characteristics vary with location in the basin and appear to be largely controlled by seasonal weather patterns and the associated winds. It appears that, at less sheltered locations, long term rates of sediment burial are controlled by frontal passages and the associated strong northerly and southerly component winds; whereas at fetch limited locations burial rates are likely controlled by stronger weather events such as tropical storms and hurricanes.

Booth, J. G.↗
NASA NTRS2009

Human Factors in Training - Space Medicine Proficiency Training

The early Constellation space missions are expected to have medical capabilities very similar to those currently on the Space Shuttle and International Space Station (ISS). For Crew Exploration Vehicle (CEV) missions to ISS, medical equipment will be located on ISS, and carried into CEV in the event of an emergency. Flight Surgeons (FS) on the ground in Mission Control will be expected to direct the Crew Medical Officer (CMO) during medical situations. If there is a loss of signal and the crew is unable to communicate with the ground, a CMO would be expected to carry out medical procedures without the aid of a FS. In these situations, performance support tools can be used to reduce errors and time to perform emergency medical tasks. Work on medical training has been conducted in collaboration with the Medical Training Group at the Space Life Sciences Directorate and with Wyle Lab which provides medical training to crew members, Biomedical Engineers (BMEs), and to flight surgeons under the JSC Space Life Sciences Directorate s Bioastronautics contract. The space medical training work is part of the Human Factors in Training Directed Research Project (DRP) of the Space Human Factors Engineering (SHFE) Project under the Space Human Factors and Habitability (SHFH) Element of the Human Research Program (HRP). Human factors researchers at Johnson Space Center have recently investigated medical performance support tools for CMOs on-orbit, and FSs on the ground, and researchers at the Ames Research Center performed a literature review on medical errors. The work proposed for FY10 continues to build on this strong collaboration with the Space Medical Training Group and previous research. This abstract focuses on two areas of work involving Performance Support Tools for Space Medical Operations. One area of research building on activities from FY08, involved the feasibility of just-in-time (JIT) training techniques and concepts for real-time medical procedures. In Phase 1, preliminary feasibility data was gathered for two types of prototype display technologies: a hand-held PDA, and a Head Mounted Display (HMD). The PDA and HMD were compared while performing a simulated medical procedure using ISS flight-like medical equipment. Based on the outcome of Phase 1, including data on user preferences, further testing was completed using the PDA only. Phase 2 explored a wrist-mounted PDA, and compared it to a paper cue card. For each phase, time to complete procedures, errors, and user satisfaction ratings were captured.

Connell, Erin↗
NASA NTRS2011

Vehicle Shield Optimization and Risk Assessment of Future NEO Missions

Future human space missions target far destinations such as Near Earth Objects (NEO) or Mars that require extended stay in hostile radiation environments in deep space. The continuous assessment of exploration vehicles is needed to iteratively optimize the designs for shielding protection and calculating the risks associated with such long missions. We use a predictive software capability that calculates the risks to humans inside a spacecraft. The software uses the CAD software Pro/Engineer and Fishbowl tool kit to quantify the radiation shielding properties of the spacecraft geometry by calculating the areal density seen at a certain point, dose point, inside the spacecraft. The shielding results are used by NASA-developed software, BRYNTRN, to quantify the organ doses received in a human body located in the vehicle in a possible solar particle events (SPE) during such prolonged space missions. The organ doses are used to quantify the risks posed on the astronauts' health and life using NASA Space Cancer Model software. An illustration of the shielding optimization and risk calculation on an exploration vehicle design suitable for a NEO mission is provided in this study. The vehicle capsule is made of aluminum shell, airlock with hydrogen-rich carbon composite material end caps. The capsule contains sets of racks that surround a working and living area. A water shelter is provided in the middle of the vehicle to enhance the shielding in case of SPE. The mass distribution is optimized to minimize radiation hotspots and an assessment of the risks associated with a NEO mission is calculated.

Nounu, Hatem, N.↗
NASA NTRS2015

Avionics Configuration Assessment for Flightdeck Interval Management: A Comparison of Avionics and Notification Methods

Flightdeck Interval Management is one of the NextGen operational concepts that FAA is sponsoring to realize requisite National Airspace System (NAS) efficiencies. Interval Management will reduce variability in temporal deviations at a position, and thereby reduce buffers typically applied by controllers - resulting in higher arrival rates, and more efficient operations. Ground software generates a strategic schedule of aircraft pairs. Air Traffic Control (ATC) provides an IM clearance with the IM spacing objective (i.e., the TTF, and at which point to achieve the appropriate spacing from this aircraft) to the IM aircraft. Pilots must dial FIM speeds into the speed window on the Mode Control Panel in a timely manner, and attend to deviations between actual speed and the instantaneous FIM profile speed. Here, the crew is assumed to be operating the aircraft with autothrottles on, with autopilot engaged, and the autoflight system in Vertical Navigation (VNAV) and Lateral Navigation (LNAV); and is responsible for safely flying the aircraft while maintaining situation awareness of their ability to follow FIM speed commands and to achieve the FIM spacing goal. The objective of this study is to examine whether three Notification Methods and four Avionics Conditions affect pilots' performance, ratings on constructs associated with performance (workload, situation awareness), or opinions on acceptability. Three Notification Methods (alternate visual and aural alerts that notified pilots to the onset of a speed target, conformance deviation from the required speed profile, and reminded them if they failed to enter the speed within 10 seconds) were examined. These Notification Methods were: VVV (visuals for all three events), VAV (visuals for all three events, plus an aural for speed conformance deviations), and AAA (visual indications and the same aural to indicate all three of these events). Avionics Conditions were defined by the instrumentation (and location) used to present IM information to crews: (1) Integrated (IM information is embedded in extant PFD (Primary Flight Display), ND (Navigation Display), EICAS (Engine Indicating and Crew Alerting System) displays); (2) EFB_Aft (IM information is only supplied in an EFB and mounted in location similar to that for MITRE's UPS work); (3) EFB_Fore (IM information is only supplied in an EFB which is mounted more forward, under the side window), and (4) EFB_Aft plus use of an AGD (the same IM information is supplied in an EFB and on an AGD, both mounted in locations similar to that in MITRE's UPS work ). Twelve commercial pilot crews flew descent scenarios (VNAV Speed with the mode control panel (MCP) speed window open until flaps extended, then VNAV Path) in a commercial transport flight simulator with realistic visual scene and communications. The results of this study serve three practical aims: (1) contribute to the down-select of avionics configuration for future assessment of the ASTAR spacing algorithm at NASA; (2) provide information useful to the FAA Human Factors Division (ANG-C1)'s mission to identify issues pertinent to flight certification of, and flight standards; (3) identify methodological considerations in support of future FIM human-in-the-loop (HITL) investigations.

Latorella, Kara A.↗
NASA NTRS2015

Peak Pc Prediction in Conjunction Analysis: Conjunction Assessment Risk Analysis

Satellite conjunction risk typically evaluated through the probability of collision (Pc). Considers both conjunction geometry and uncertainties in both state estimates. Conjunction events initially discovered through Joint Space Operations Center (JSpOC) screenings, usually seven days before Time of Closest Approach (TCA). However, JSpOC continues to track objects and issue conjunction updates. Changes in state estimate and reduced propagation time cause Pc to change as event develops. These changes a combination of potentially predictable development and unpredictable changes in state estimate covariance. Operationally useful datum: the peak Pc. If it can reasonably be inferred that the peak Pc value has passed, then risk assessment can be conducted against this peak value. If this value is below remediation level, then event intensity can be relaxed. Can the peak Pc location be reasonably predicted?

Operations↗
NASA NTRS2016

The Design, Implementation, and Performance of the Astro-H SXS Calorimeter Array and Anti-Coincidence Detector

The calorimeter array of the JAXA Astro-H (renamed Hitomi) Soft X-ray Spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV, enabling essential plasma diagnostics. The SXS has a square array of 36 microcalorimeters at the focal plane. These calorimeters consist of ion-implanted silicon thermistors and HgTe thermalizing x-ray absorbers. These devices have demonstrated a resolution of better than 4.5 eV at 6 keV when operated at a heat-sink temperature of 50 mK. We will discuss the basic physical parameters of this array, including the array layout, thermal conductance of the link to the heat sink, resistance function, absorber details, and means of attaching the absorber to the thermistor-bearing element. We will also present the thermal characterization of the whole array, including thermal conductance and crosstalk measurements and the results of pulsing the frame temperature via alpha particles, heat pulses, and the environmental background. A silicon ionization detector is located behind the calorimeter array and serves to reject events due to cosmic rays. We will briefly describe this anti-coincidence detector and its performance.

x-ray calorimeter↗
NASA NTRS2018

Design, Implementation, and Performance of the Astro-H SXS Calorimeter Array and Anticoincidence Detector

The calorimeter array of the JAXA Astro-H (renamed Hitomi) soft x-ray spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV, enabling essential plasma diagnostics. The SXS had a square array of 36 x-ray calorimeters at the focal plane. These calorimeters consisted of ion-implanted silicon thermistors and HgTe thermalizing x-ray absorbers. These devices demonstrated a resolution of better than 4.5 eV at 6 keV when operated at a heat-sink temperature of 50 mK. We will discuss the basic physical parameters of this array, including the array layout, thermal conductance of the link to the heat sink, resistance function, absorber details, and means of attaching the absorber to the thermistor-bearing element. We will also present the thermal characterization of the whole array, including thermal conductance and crosstalk measurements and the results of pulsing the frame temperature via alpha particles, heat pulses, and the environmental background. A silicon ionization detector was located behind the calorimeter array and served to reject events due to cosmic rays. We will briefly describe this anticoincidence detector and its performance.

Kilbourne, Caroline A.↗
NASA NTRS2020

Urban Air Mobility System Testbed Using CAVE Virtual Reality Environment

Urban Air Mobility (UAM) refers to a system of air passenger and small cargo transportation within an urban area. The UAM framework also includes other urban Unmanned Aerial Systems (UAS) services that will be supported by a mix of onboard, ground, piloted, and autonomous operations. Over the past few years UAM research has gained wide interest from companies and federal agencies as an on-demand innovative transportation option that can help reduce traffic congestion and pollution as well as increase mobility in metropolitan areas. The concepts of UAM/UAS operation in the National Airspace System (NAS) remains an active area of research to ensure safe and efficient operations. With new developments in smart vehicle design and infrastructure for air traffic management, there is a need for methods to integrate and test various components of the UAM framework. In this work, we report on the development of a virtual reality (VR) testbed using the Cave Automatic Virtual Environment (CAVE) technology for human-automation teaming and airspace operation research of UAM. Using a four-wall projection system with motion capture, the CAVE provides an immersive virtual environment with real-time full body tracking capability. We created a virtual environment consisting of San Francisco city and a vertical take-off-and-landing passenger aircraft that can fly between a downtown location and the San Francisco International Airport. The aircraft can be operated autonomously or manually by a single pilot who maneuvers the aircraft using a flight control joystick. The interior of the aircraft includes a virtual cockpit display with vehicle heading, location, and speed information. The system can record simulation events and flight data for post-processing. The system parameters are customizable for different flight scenarios; hence, the CAVE VR testbed provides a flexible method for development and evaluation of UAM framework.

Marayong, Panadda↗
NASA NTRS2021

A Ring Accelerator? Unusual Jet Dynamics in the IceCube Candidate PKS 1502+106

On 2019/07/30.86853 UT, IceCube detected a high-energy astrophysical neutrino can-didate. The Flat Spectrum Radio Quasar PKS 1502+106 is located within the 50 percent uncertainty region of the event. Our analysis of 15 GHz Very Long Baseline Ar-ray (VLBA) and astrometric 8 GHz VLBA data, in a time span prior and after theIceCube event, reveals evidence for a radio ring structure which develops with time.Several arc-structures evolve perpendicular to the jet ridge line. We find evidence forprecession of a curved jet based on kinematic modelling and a periodicity analysis.An outflowing broad line region (BLR) based on the C IV line emission (Sloan Dig-ital Sky Survey, SDSS) is found. We attribute the atypical ring to an interaction ofthe precessing jet with the outflowing material.We discuss our findings in thecontext of a spine-sheath scenario where the ring reveals the sheath andits interaction with the surroundings (NLR clouds).We find that the radioemission is correlated with theγ-ray emission, with radio lagging theγ-rays. Basedon theγ-ray variability timescale, we constrain theγ-ray emission zone to the BLR(30-200rg) and within the jet launching region. We discuss that the outflowing BLRprovides the external radiation field forγ-ray production via external Compton scat-tering.The neutrino is most likely produced by proton-proton interactionin the blazar zone (beyond the BLR), enabled by episodic encounters ofthe jet with dense clouds, i.e. some molecular cloud in the NLR.

S Britzen↗
NASA NTRS2024

Improved Modelling of SEP Event Onset Within the WSA–Enlil–SEPMOD Framework

Multi-spacecraft observations of solar energetic particle (SEP) events not only enable a deeper understanding and development of particle acceleration and transport theories but also provide important constraints for model validation efforts. However, because of computational limitations, a given physics-based SEP model is usually best suited to capture a particular phase of an SEP event, rather than its whole development from onset through decay. For example, magnetohydrodynamic (MHD) models of the heliosphere often incorporate solar transients only at the outer boundary of their so-called coronal domain – usually set at a heliocentric distance of 20–30 R⊙. This means that particle acceleration at coronal mass ejection (CME)-driven shocks is also computed from this boundary onwards, leading to simulated SEP event onsets that can be many hours later than observed, since shock waves can form much lower in the solar corona. In this work, we aim to improve the modelled onset of SEP events by inserting a “fixed source” of particle injection at the outer boundary of the coronal domain of the coupled WSA–Enlil 3D MHD model of the heliosphere. The SEP model that we employ for this effort is Solar Energetic Particle MODel (SEPMOD), a physics-based test-particle code based on a field line tracer and adiabatic invariant conservation. We apply our initial tests and results of SEPMOD’s fixed-source option to the 2021 October 9 SEP event, which was detected at five well-separated locations in the inner heliosphere – Parker Solar Probe, STEREO-A, Solar Orbiter, BepiColombo, and near-Earth spacecraft.

Solar eruptions↗
NASA NTRS2005

Flux Transfer Event in the Subsolar Region and Near the Cusp: Simultaneous Polar and Cluster Observations

The phenomenon called flux transfer events (FTEs) is widely accepted as the manifestation of time-dependent reconnection. In this paper, we present an observational evidence of a flux transfer event observed simultaneously at low-latitude by Polar and high-latitude by Cluster. This event occurred on March 21, 2002, when both Cluster and Polar were located near the local noon but with large latitudinal distance. Cluster was moving outbound from polar cusp to the magnetosheath, and Polar was in the magnetosheath near the equatorial magnetopause. The observations show that a flux transfer event was formed between the equator and the northern cusp. Polar and Cluster observed the FTE's two open flux tubes: Polar saw the southward moving flux tube near the equator; and Cluster the , northward moving flux tube at high latitude. Unlike low-latitude FTEs, the high-latitude FTE did not exhibit the characteristic bi-polar BN signature. But the plasma data clearly showed its open flux tube configuration. Enhanced electric field fluctuations were observed within the FTE core, both at low- and high-attitudes. This event provides us a unique opportunity to understand high-latitude FTE signatures and the nature of time-varying reconnection.

Le, G.↗
NASA NTRS1975

Energy, frequency, and distance of moonquakes at the Apollo 17 site

'Thermal' moonquakes have been detected at the Apollo 17 site. A typical event releases about 1 to 10 million ergs of energy. The annual seismic energy release for the events observed in the Taurus-Littrow Valley is estimated at 100 billion ergs. Such small events would not cause impossibly rapid erosion on either the North Massif or within the craters of the Central Cluster. Seismic events become increasingly frequent after sunrise and reach a maximum at sunset. The largest events, however, occur most commonly near lunar noon. Rise times of the seismic signals, after being calibrated by the well-located Lunar Seismic Profiling Experiment (LSPE) seismic sources, were used to estimate distances to the seismic events. Most seismic events (about 90%) appear to occur within 2.5 km of the seismometer array.

Cooper, M. R.↗
NASA NTRSDate not supplied

Buckling Testing of a Subscale Composite Cylinder

A subscale solid laminate composite cylinder with a 31.5-in. diameter, a 48.2-in. length, and a [23/0/-23]4S layup was designated NDL-1 and was designed to fail in buckling after a series of subcritical tests. NDL-1 was experimentally loaded in axial compression until buckling at 466.3 kips. Visual inspection of the test article after the test revealed that a shallow area of delamination occurred near the buckling initiation site. After a successful first buckling test, there was an opportunity to test NDL-1 in axial compression to failure a second time despite that the test article was not designed or analyzed for multiple buckling tests. During the second test to failure, NDL-1 reached a peak load of 390.4 kips, 16.3% lower than the first test. Buckling did not initiate in the same location during the second test to failure as the first test to failure. The second buckling event caused a large V-shaped crack that penetrated through the thickness of the barrel. Though buckling initiated at different locations, a similar radial deformation pattern was present just prior to buckling during the both tests. In the end, NDL-1 maintained a significant amount of its structural integrity and a similar prebuckling radial displacement pattern, even after the first buckling test.

Test↗
NASA NTRS2011

The Correlation of Interphase Chromatin Structure with the Radiation-Induced Inter- and Intrachromosome Exchange Hotspots

To investigate the relationship between chromosome aberrations induced by radiation and chromatin folding, we reconstructed three dimensional structure of chromosome 3 and measured the physical distances between different regions of the chromosome. Previously, we have investigated the location of breaks involved in inter- and intrachromosomal type exchange events in human chromosome 3, using the multicolor banding in situ hybridization (mBAND) technique. In human epithelial cells exposed to both low- and high-LET radiations in vitro, we reported that intra-chromosome exchanges occurred preferentially between a break in the 3p21 and one in the 3q11 regions, and the breaks involving in inter-chromosome exchanges occurred in two regions towards the telomeres of the chromosome. Exchanges were also observed between a break in 3p21 and one in 3q26, but few exchanges were observed between breaks in 3q11 and 3q26, even though the two regions are located on the same arm of the chromosome. In this study, human epithelial cells were fixed at G1 phase and the interphase cells were hybridized using the XCyte3 mBAND kit from MetaSystems. The z-section images of chromosome 3 were captured with a Leica and an LSM 510 Meta laser scanning confocal microscopes. A total of 100 chromosomes were analyzed. The reconstruction of three dimensional structure of interphase chromosome 3 with six different colored regions was achieved using the Imaris software. The relative distance between different regions was measured as well. We further analyzed fragile sites on the chromosome that have been identified in various types of cancers. The data showed that, in majority of the cells, the regions containing 3p21 and 3q11 are colocalized in the center of the chromosome, whereas, the regions towards the telomeres of the chromosome are either physically wrapping outside the chromosome center or with arms sticking out. Our results demonstrated that the distribution of breaks involved in radiation-induced inter and intra-chromosome aberrations depends upon both the location of fragile sites and the folding of chromatins.

Zhang, Ye↗
DOE OSTI2024

Impact of Electric Vehicle Charging Station Reliability, Resilience, and Location on Electric Vehicle Adoption

While the majority of electric vehicle (EV) charging events in the United States occur at home, issues with public charging stations are consistently found to be a top reason that potential EV buyers do not purchase an EV, demonstrating that both EVSE reliability and availability impacts EV adoption. This report explores multiple parameters that impact EVSE reliability and deployment, which in turn impact EV sales. These include extreme weather, codes and standards, region (urban vs. rural), and grid network type. Grid reliability was not found to impact EV adoption. The relationships between EV station reliability, station resilience, grid resilience, and EV adoption are largely outside the scope of the National Renewable Energy Laboratory's (NREL's) Automotive Deployment Options Projection Tool (ADOPT) and other vehicle adoption models, so the methodology of this report is varied. Section 2 sets the baseline for infrastructure reliability, user satisfaction, and maintenance practices. Section 3 explores the ways that electric vehicle supply equipment (EVSE) reliability impacts the relationship between EVSE and EV adoption. Section 4 shows how geographical categories such as urban, rural, large grid, off-grid, or microgrid can be helpful in EVSE deployment strategies, as well as how the relationship between EVSE and EV adoption differs among these categories. Section 5 investigates the impacts of grid reliability and infrastructure resilience on EV adoption. Finally, Section 6 reverses the perspective to examine the impact that EVs and EVSE have on grid resilience and reliability. As recent funding initiatives result in an expansion of public chargers across the United States, as well as an increase in the uptime of existing chargers, EV adoption will likely grow.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS1989

Impulsive acceleration and scatter-free transport of about 1 MeV per nucleon ions in (He-3)-rich solar particle events

Impulsive solar energetic particle (SEP) events are studied to: (1) describe a distinct class of SEP ion events observed in interplanetary space, and (2) test models of focused transport through detailed comparisons of numerical model prediction with the data. An attempt will also be made to describe the transport and scattering properties of the interplanetary medium during the times these events are observed and to derive source injection profiles in these events. ISEE 3 and Helios 1 magnetic field and plasma data are used to locate the approximate coronal connection points of the spacecraft to organize the particle anisotropy data and to constrain some free parameters in the modeling of flare events.

Mason, G. M.↗