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All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

Motion Sickness and Concerns for Urban Air Mobility Vehicles: A Literature Review

Motion sickness is a general term for a constellation of signs and symptoms, generally due to exposure to abrupt, periodic, or unnatural accelerations, especially when traveling in a vehicle. Motion sickness results from a mismatch of the visual and nonvisual (vestibular and kinesthetic) information, the observed scene and the motion felt or lack of it. Motion sickness onset is associated with a pattern of physiological changes in heart rate, peripheral blood flow, respiration, and skin conductance and the pattern is repeatable for a particular subject but variable between subjects. Demographic factors such as gender and age that affect motion sickness are well known with children, women, and older adults more likely to be susceptible. Often motion sickness is assessed and quantified using variations of the motion sickness susceptibility questionnaires including the Pensacola Diagnostic Rating Scale and the Simulator Sickness Questionnaire. Even though symptoms are easily identified by such questionnaires, they commonly are subjective. Tools such as these questionnaires for screening individuals susceptible to motion sickness are useful, however, they are only mildly predictive. Moreover, models for predicting motion sickness, which have largely been developed for sea sickness, do not consider task characteristics. Predictions of motion sickness rates and prevalence for Urban Air Mobility (UAM) vehicles are not possible at present because data from actual flight or full-fidelity simulation are simply not yet available. Extrapolation from other modes of transportation (i.e., automobiles, buses, trains, boats, other types of aircraft) is difficult because of differences in the motion stimulus experienced, trip duration, and other factors. How UAM vehicles will change the social dynamics of passenger interaction and vehicle interior design changes (e.g., seat orientations) is unknown. Should motion sickness prove to be an issue, vehicle design modifications such as having passengers face forward, providing additional seat recline, giving each person their own climate control for airflow, perhaps ensuring the horizon is visible to all passengers (reducing visual occlusion by the headrest) and visually stabilizing displays on carry-on devices (smart phones, tablets, etc.) may benefit passengers. Several commercial companies provide wearable devices for physiological monitoring that have been validated and are suitable for use with passengers in UAM vehicles or high-fidelity simulators. Potential countermeasures for motion sickness include user-worn devices, anti-motion sickness medications, and non-pharmacological approaches such as biofeedback and Autogenic Feedback Training Exercise. Both simulator and in-vehicle UAM research is needed to evaluate the effectiveness of any potential countermeasure.

motion sickness↗
NASA NTRS1988

Construction and analysis of simulated Venera and Magellan images of Venus

The 1-3 km resolution Venera 15 and 16 images of Venus and the expected 120-300 m resolution Magellan mission image data are presently simulated through a digital processing of Seasat radar images covering a desert dune complex in the Gran Desierto of Sonora, accreted terranes in the central interior of Alaska, and the Appalachian Valley and Ridge Province. The simulations suggest that the nature and extent of terrain modification on Venus by such exogenic processes as atmosphere-surface weathering, erosion, and deposition, will remain uncertain, since the length scale of features indicative of such processes may be too small to be discerned from Venera data; Magellan data may provide this critical fine-scale morphological data, however, and thereby allow the testing of the two competing resurfacing scenarios.

Arvidson, R. E.↗
NASA NTRS2018

Probing Supraglacial Debris on Mars 2: Crater Morphology

Lobate debris aprons (LDA), lineated valley fill (LVF), and concentric crater fill (CCF) on Mars, interpreted to bedebris-covered glaciers, possess craters with a suite of distinct interior landforms (called "ring-mold craters")that have been attributed to the presence of glacial ice at depth or surface modification processes. We testedcurrent hypotheses for the formation of ring-mold craters by conducting a comprehensive analysis of the size andmorphology of 16,457 impact craters 125m in diameter formed within glacial deposits in DeuteronilusMensae. Two major groups, bowl-shaped craters and ring-mold craters, are found, with at least nine distinctcrater types. While there is statistical difference in median diameters between these crater types, this differenceis relatively small and is within the estimated uncertainty in diameter measurements and may be related to moreenhanced erosion of the rims of ring-mold craters. Clear degradation sequences are observed, supporting a rolefor post-impact modification in producing at least some of the diversity in crater landforms. The spatial densityof ring-mold craters is also directly correlated with the development of LDA, LVF, and CCF surface textures. Flowlineations cross-cut two ring-mold crater types but they maintain their circular planforms in some cases, suggestingthat the craters initially formed completely within mantling layers deposited after glacial flow hadceased. We also find analogous craters in non-glacial units; glacial ice is therefore not required to form theobserved morphologic diversity. Our observations are most consistent with formation of crater landforms byemplacement and modification of at least two depositional episodes of icy dust (i.e., "mantle"). This mantle wasinitially tens of meters in thickness to support crater formation, and has experienced much downwasting anderosion since emplacement. Derived crater retention ages of 460 Ma for LDA, LVF, and CCF features in the regiontherefore reflect deposition of mantle units and only give a very minimum age for the formation of LDA, LVF, andCCF

Geological↗
DOE OSTI2020

Structural Modifications of Single-Crystal Aragonite CaCO 3 Beginning at ~15 GPa: In Situ Vibrational Spectroscopy and X-Ray Diffraction Evidence

The structural chemistry of carbonates under mantle conditions facilitates our understanding of carbon recycling pathways in the earth’s interior. It also has impacts on the dynamics of mantle–slab interactions. Aragonite is a common calcium carbonate mineral in pelagic marine sediments. The structural chemistry of single-crystal aragonite during successive compression and the behavior of a structural H+ have been investigated by micro-vibrational spectroscopy and synchrotron X-ray diffraction techniques in diamond anvil cells. We describe a reduction of the b-axial compressibility beginning at ~15 GPa, and the related discontinuities in the first-order derivatives of the vibrational modes. The structural modifications of aragonite are manifested by mutations occurring in the pressure relations of the wavenumbers of the O-C-O bending modes, and of the bandwidth and band intensities of the measured internal and external modes. These anomalies are indicative of changes occurring in the force constant of the C-O bonds, and possibly a second-order phase transition. Besides, the [CaO 9 ] polyhedra begin to deform, possibly with some Ca-O bonds becoming elongated and the others shortening. An increase in the co-ordination number for the Ca 2+ sites could be expected under higher pressures. Additionally, the weakening of the OH modes may imply H + -loss from the aragonite lattice above 11.5 GPa.

58 GEOSCIENCES↗
NASA NTRS1989

Crater formation and modification on the icy satellites of Uranus and Saturn - Depth/diameter and central peak occurrence

Fresh crater shapes, in particular crater depth/diameter ratios d/D, have been measured for craters on nine of the icy satellites. Crater depths were determined from photoclinometry plus some shallow measurements. Interior morphology, including rimwall slope, was also examined from photoclinometry profiles. Central peak statistics and the characteristic break in slope of d/D curves were determined in order to estimate the transition diameter from simple to complex craters. Crater morphology and transition diameters on the icy satellites were then compared with crater morphology on the terrestrial rocky planets in order to separate or evaluate the relative importance and similarity of surface gravity and target characteristics in controlling crater formation and modification in icy and rocky targets. Estimates of effective rheologies of the target materials were also obtained based on morphologic changes.

Schenk, Paul M.↗
NASA NTRS2020

Modification of Caloris ejecta blocks by long-lived mass-wasting: A volatile-driven process?

The Caloris basin is the largest well-preserved impact basin on Mercury. As such, Caloris ejecta afford us an opportunity to study material from Mercury's deep interior with remote sensing. We have made observations of the geomorphology, colour, distribution, and flank slopes of the circum-Caloris knobs. Our observations suggest that these circum-Caloris knobs are modified ejecta blocks from the Caloris impact. High-resolution MESSENGER images show that knobs are conical and relatively uncratered compared with the surrounding plains, which implies the knobs have undergone resurfacing. We have observed material that has sloughed off knobs superposing impact craters that demonstrably postdate the Caloris impact, which requires some knob modification to have been more recent. We have observed hollows, depressions in Mercury's surface generally believed to have been caused by volatile-loss, on and closely associated with several knobs, which indicates that many knobs contain volatile material and that knob modification could extend into Mercury's recent past. Our measurements show that knob flanks typically have slopes of ∼21°, which is steep for a mound of unconsolidated material that was originally emplaced ∼3.8 Ga. The conical shape of knobs, their steep slopes, the dearth of superposed craters on knobs, and knob superposition relationships with other landforms suggest that Caloris ejecta blocks of arbitrary original shape were modified into their present shapes by long-lived mass-wasting. Mass-wasting must have dominated over impact gardening, which would have produced domal morphologies only. We suggest that mass-wasting was probably driven by volatile-loss, in a manner analogous to terrestrial landforms called ‘molards’. If the circum-Caloris knobs are analogous to molards, then they represent a landform and a process hitherto undocumented on Mercury, with implications for the volatile content of the planet's interior. These knobs therefore are prime targets for BepiColombo, which could search for fresh failures and volatile exposures in the knobs.

Mercury; Caloris basin; impact ejecta; volatiles; ↗
NASA NTRS2016

Formation of Oxides in the Interior of Friction Stir Welds

In friction stir welding (FSWing) the actual solid state joining takes place between the faying surfaces which form the weld seam. Thus the seam trace is often investigated for clues when the strength of the weld is reduced. Aluminum and its alloys are known to form a native, protective oxide on the surface. If these native surface oxides are not sufficiently broken up during the FSW process, they are reported to remain in the FSW interior and weaken the bond strength. This type of weld defect has been referred to as a lazy "S", lazy "Z", joint line defect, kissing bond, or residual oxide defect. Usually these defects are mitigated by modification of the process parameters, such as increased tool rotation rate, which causes a finer breakup of the native oxide particles. This study proposes that there may be an alternative mechanism for formation of oxides found within the weld nugget. As the oxidation rate increases at elevated temperatures above 400ºC, it may be possible for enhanced oxidation to occur on the interior surfaces during the FSW process from entrained air entering the seam gap. Normally, FSWs of aluminum alloys are made without a purge gas and it is unknown how process parameters and initial fit up could affect a potential air path into the interior during the processing. In addition, variations in FSW parameters, such as the tool rotation, are known to have a strong influence on the FSW temperature which may affect the oxidation rate if internal surfaces are exposed to entrained air. A series of FSWs were made in 3 different thickness panels of AA2219 (0.95, 1.27 and 1.56 cm) at 2 different weld pitches. As the thickness of the panels increased, there was an increased tendency for a gap to form in advance of the weld tool. If sufficient air is able to enter the workpiece gap prior to consolidation, the weld temperature can increase the oxidation rate on the interior surfaces. These oxidation rates would also be accelerated in areas of localized liquation. Metallographs from the weld panels showed indications of liquation at the grain boundaries. In FSWs of thicker panels, these regions of liquation were found to be heavily oxidized. The quality of the FSWs was evaluated from tensile testing at room temperature. As the panel thickness increased, a slight decrease in tensile strength was observed which was attributed to the presence of oxides. No oxide formation was observed in the thinner workpieces, although there were indications of localized liquation at the grain boundaries. Results from this study will assist in a better understand of the mechanisms of oxide formation in FSW interiors and provide methodology for minimizing their occurrence.

Schneider, Judy↗
NASA NTRS1977

C-shaped specimen plane strain fracture toughness tests

Test equipment, procedures, and data obtained in the evaluation of C-shaped specimens are presented. Observations reported on include: specimen preparation and dimensional measurement; modifications to the standard ASTM E 399 displacement gage, which permit punch mark gage point engagement; and a measurement device for determining the interior and exterior radii of ring segments. Load displacement ratios were determined experimentally which agreed with analytically determined coefficients for three different gage lengths on the inner surfaces of radially-cracked ring segments.

Buzzard, R. T.↗
NASA NTRS1979

STS mission duration enhancement study: (orbiter habitability)

Habitability improvements for early flights that could be implemented with minimum impact were investigated. These included: (1) launching the water dispenser in the on-orbit position instead of in a locker; (2) the sleep pallet concept; and (3) suction cup foot restraints. Past studies that used volumetric terms and requirements for crew size versus mission duration were reviewed and common definitions of key habitability terms were established. An accurately dimensioned drawing of the orbiter mid-deck, locating all of the known major elements was developed. Finally, it was established that orbiter duration and crew size can be increased with minimum modification and impact to the crew module. Preliminary concepts of the aft med-deck, external versions of expanded tunnel adapters (ETA), and interior concepts of ETA-3 were developed and comparison charts showing the various factors of volume, weight, duration, size, impact to orbiter, and number of sleep stations were generated.

Carlson, A. D.↗
NASA NTRS2002

The SOFIA Aircraft and its Modification

The primary focus of this paper is to describe the challenges involved in creating this highly modified aircraft that carries a twenty ton telescope to the Stratosphere and then loiters at this desired altitude to act as the observatory "dome" or platform. When the aircraft has reached its nominal cruise condition in the stratosphere of Mach 0.84, a large cavity door opens (the dome opens), exposing a large portion of the interior of the fuselage containing the telescope optics, directly to the Universe. The breadth of topics covered in this paper includes; the relevant criteria and the evaluation process that resulted in the selection of a Boeing 747-SP, the evolution of the design concept, a description of the structural modification including the analysis methods and tools, the aerodynamic issues associated with an open port cavity and how they were addressed, the aero-loads/disturbances imparted to the telescope and how they were measured in the wind tunnel and extrapolated to full size. For completeness, this paper also provides a brief overview of the SOFIA project including the joint project arrangement between NASA and DLR, a top level overview of the science objectives and the resulting requirements, and finally the current project status.

Kunz, Nans↗
NASA NTRS1983

Computed tomographic analysis of meteorite inclusions

The feasibility of obtaining nondestructively a cross-sectional display of very dense heterogeneous rocky specimens, whether lunar, terrestrial or meteoritic, by using a fourth generation computed tomographic (CT) scanner, with modifications to the software only, is discussed. A description of the scanner, and of the experimental and analytical procedures is given. Using this technique, the interior of heterogeneous materials such as Allende can be probed nondestructively. The regions of material with high and low atomic numbers are displayed quickly; the object can then be cut to obtain for analysis just the areas of interest. A comparison of this technique with conventional industrial and medical techniques is made in terms of image resolution and density distribution display precision.

Arnold, J. R.↗
NASA NTRS1992

Toward the optimization of control of unsteady separation

Regardless of our understanding of the complicated physical process, means can always be found to alter the occurrence and development of unsteady separation. To be able to optimize the control of separation, however, requires the identification of the critical aspects to which the intervention may be focused and achieve the desired result with minimum waste of effort. The Lagrangian analysis of unsteady boundary-layer traces the trajectories of individual fluid particles and reveals the 'bad seeds' that, through extreme deformation in the direction normal to the wall, eventually develop into a virtual barrier and cause the ejection of boundary-layer material into the main stream. It follows logically that separation can be triggered or delayed most effectively by targeting these 'bad seeds.' Since they are normally interior points of the boundary layer, attempts to influence them through the boundary conditions are necessarily indirect. Furthermore, as the strategy has to be the modification of the growing process of the 'bad seeds,' whatever may be the intervention scheme, it needs to be strong enough and early enough. In Shen and Wu, examples of how acceleration/deceleration of the two dimensional body, as well as the moving wall of a rotating cylinder, may affect the development of the bad seed toward separation are shown. In fact it was mentioned therein that the results might be the first step for a feasibility study of the control of unsteady separation. Presented are additional results of applying suction to an impulsively started circular cylinder.

Shen, S. F.↗
NASA NTRS1989

Test of a geometric model for the modification stage of simple impact crater development

This paper presents a geometric model describing the geometry of the transient cavity of an impact crater and the subsequent collapse of its walls to form a crater filled by an interior breccia lens. The model is tested by comparing the volume of slump material calculated from known dimensional parameters with the volume of the breccia lens estimated on the basis of observational data. Results obtained from the model were found to be consistent with observational data, particularly in view of the highly sensitive nature of the model to input parameters.

Grieve, R. A. F.↗
DOE OSTI2020

Neodymium-iron-boron magnet with selective surface modification, and method of producing same

A bulk high performance permanent magnet comprising a neodymium-iron-boron core having an outer surface, and a coercivity-enhancing element residing on at least a portion of said outer surface, with an interior portion of said neodymium-iron-boron core not having said coercivity-enhancing element therein. Also described herein is a method for producing the high-coercivity bulk permanent magnet, the method comprising: (i) depositing a coercivity-enhancing element on at least a portion of an outer surface of a neodymium-iron-boron core substrate to form a coated permanent magnet; and (ii) subjecting the coated permanent magnet to a pulse thermal process that heats said outer surface to a substantially higher temperature than an interior portion of said neodymium-iron-boron core substrate, wherein said substantially higher temperature is at least 200° C. higher than said interior portion and is of sufficient magnitude to induce diffusion of said coercivity-enhancing element below said outer surface but outside of said interior portion.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1981

Energy absorption studied to reduce aircraft crash forces

The NASA/FAA aircraft safety reseach programs for general aviation aircraft are discussed. Energy absorption of aircraft subflooring and redesign of interior flooring are being studied. The testing of energy absorbing configurations is described. The three NASA advanced concepts performed at neary the maximum possible amount of energy absorption, and one of two minimum modifications concepts performed well. Planned full scale tests are described. Airplane seat concepts are being considered.

Source record↗
NASA NTRS1997

Physical Processing of Cometary Nuclei

Cometary nuclei preserve a cosmo-chemical record of conditions and processes in the primordial solar nebula, and possibly even the interstellar medium. However, that record is not perfectly preserved over the age of the solar system due to a variety of physical processes which act to modify cometary surfaces and interiors. Possible structural and/or internal processes include: collisional accretion, disruption, and reassembly during formation; internal heating by long and short-lived radionuclides; amorphous to crystalline phase transitions, and thermal stresses. Identified surface modification processes include: irradiation by galactic cosmic rays, solar protons, UV photons, and the Sun's T Tauri stage mass outflow; heating by passing stars and nearby supernovae; gardening by debris impacts; the accretion of interstellar dust and gas and accompanying erosion by hypervelocity dust impacts and sputtering; and solar heating with accompanying crust formation. These modification processes must be taken into account in both the planning and the interpretation of the results of a Comet Nucleus Sample Return Mission. Sampling of nuclei should be done at as great a depth below the surface crust as technically feasible, and at vents or fissures leading to exposed volatiles at depth. Samples of the expected cometary crust and near-surface layers also need to be returned for analysis to achieve a better understanding of the effects of these physical processes. We stress that comets are still likely less modified dm any other solar system bodies, but the degree of modification can vary greatly from one comet to the next.

Weissman, Paul R.↗
NASA NTRS2022

Thermal Stress Weathering of Boulders on Airless Bodies

Rock boulders are considerably typical of airless rocky bodies throughout the inner solar system, so their environments prove useful to understanding the rates of surface-modification processes and “survival times” of these boulders. On the Moon, there are meter-sized boulders on the rims of small lunar carters of some known age, so modeling the rock destruction is applied. Interior and exterior stresses must be considered, including thermal day-night cycling of the regolith and sub-regolith, and solar wind.

Caitlin Ahrens↗
NASA NTRS2020

Science of the Moon

Science of the Moon discusses the present state of knowledge of the Moon, as well as the scientific questions remaining about the Moon's history and current attributes. This chapter covers events in lunar history, the geology of the Moon, properties and modification of the lunar regolith, the effects of radiation on the lunar surface, volatiles including those in the lunar Permanently Shadowed Regions, as well as the lunar seismic environment and what it indicates about the lunar interior. The chapter also lists instruments that, when deployed on the Moon or utilized in a lunar sample analysis facility in a lunar base, contribute to knowledge of the Moon. Presented within the chapter are unanswered questions regarding cratering on the lunar surface, the transition from bedrock to regolith, lunar tectonism, the crustal structure and composition of the Moon, reserve potential for in-situ resources, and the nature of the volatiles on the Moon.

Lunar science, Moon, geology, geophysics↗