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NASA NTRSDate not supplied

A Crew Seat for Human Exploration in Multiple Gravity Environments

This work attempts to develop a single crew seating solution that is applicable across a range of gravity environments encountered by spacecraft proposed in several conceptual spacecraft architectures. All of these spacecraft will need to provide some sort of stationary accommodation for the crew for performing various activities such as work in science laboratories, maintenance and repair facilities, medical care facilities, and spacecraft operations centers, as well as for basic habitation in crew quarters, entertainment / relaxation facilities, and crew dining facilities. Depending on the spacecraft or architecture, this stationary accommodation may be experienced continuously in microgravity, such as would be the case for the Deep Space Exploration Vehicle. Alternately, it could be in continuous lunar or Martian gravity, such as the Common Habitat base camps. It could experience fractional gravity, such as a Pressurized Rover for In-Space Missions at a Near Earth Asteroid or one of the Martian moons. It could alternate between artificial gravity and microgravity, such as the Nautilus-X. It could alternate between microgravity and lunar or Martian gravity, such as the SpaceX Starship Human Landing System or the Blue Origin Blue Moon Block 2 Human Landing System. Or it could be in continuous Earth gravity, such as ground trainer systems. Prior human spaceflight systems for stationary accommodation have been focused on microgravity applications. These systems have their own limitations and cannot be used in a gravity environment. A public crowdsourcing campaign generated dozens of ideas, which ultimately generated a Gecko Mobility Aids system for crew translation and the Multi-Gravity Crew Seat (MGCS) for stationary accommodation. The MGCS functions in gravity as a traditional terrestrial seat, performing functions of load for the overall body and forearms, as well as head and neck load relief while positioning the body within range of an intended task. In microgravity, the MGCS functions as a body restraint, securing the body against inadvertent drifting by applying a restraining pressure at the front and back of the thighs, shoulders, and back. The initial MGCS concept was developed in a NASA hackathon and was refined through a review of dozens of terrestrial seating styles. Additionally, a review of anthropometry and biomechanics data related to the neutral body posture was conducted to help inform the microgravity configuration of the MGCS. A series of CAD models were iteratively developed, with subject matter expert reviews leading to design improvements. A scale model was constructed and used with a humanoid model to demonstrate MGCS accommodation of a human-like body in both gravity and microgravity modes. Work to develop a full-scale protype of the MGCS is discussed, including design and fabrication of the headrest, arm rest, seat back, seat pan, seat base, and the conversion mechanisms. A 1-g human-in-the-loop evaluation of the prototype assessed the acceptability of performing seated activities in the MGCS, collecting data on the usability, comfort, and ease of ingress/egress. Based on the evaluation results, design modifications needed for reduced gravity testing are documented and initial work is indicated for a reduced gravity test plan.

Restraints and Mobility Aids↗

NASA NTRS2022

A Multimodel Investigation of Asian Summer Monsoon UTLS Transport Over the Western Pacific

The Asian summer monsoon (ASM) as a chemical transport system is investigated using a suite of models in preparation for an airborne field campaign over the Western Pacific. Results show that the dynamical process of anticyclone eddy shedding in the upper troposphere rapidly transports convectively uplifted Asian boundary layer air masses to the upper troposphere and lower stratosphere over the Western Pacific. The models show that the transported air masses contain significantly enhanced aerosol loading and a complex chemical mixture of trace gases that are relevant to ozone chemistry. The chemical forecast models consistently predict the occurrence of the shedding events, but the predicted concentrations of transported trace gases and aerosols often differ between models. The airborne measurements to be obtained in the field campaign are expected to help reduce the model uncertainties. Furthermore, the large-scale seasonal chemical structure of the monsoon system is obtained from modeled carbon monoxide, a tracer of the convective transport of pollutants, which provides a new perspective of the ASM circulation, complementing the dynamical characterization of the monsoon.

Laura L. Pan↗

NASA NTRS1992

Quantitative analysis of surface characteristics and morphology in Death Valley, California using AIRSAR data

The Jet Propulsion Laboratory Airborne Synthetic Aperture Radar (JPL-AIRSAR) is used to collect full polarimetric measurements at P-, L-, and C-bands. These data are analyzed using the radar analysis and visualization environment (RAVEN). The AIRSAR data are calibrated using in-scene corner reflectors to allow for quantitative analysis of the radar backscatter. RAVEN is used to extract surface characteristics. Inversion models are used to calculate quantitative surface roughness values and fractal dimensions. These values are used to generate synthetic surface plots that represent the small-scale surface structure of areas in Death Valley. These procedures are applied to a playa, smooth salt-pan, and alluvial fan surfaces in Death Valley. Field measurements of surface roughness are used to verify the accuracy.

Kierein-Young, K. S.↗

NASA NTRS1984

Impact of fuselage incidence on the supersonic aerodynamics of two fighter configurations

The results of experimental and theoretical investigations into the effect of fuselage upwash on fighter aircraft wing performance are reported. Wind tunnel trials were performed on 4 percent scale models of two supersonic fighters. The trials were run at Mach 1.6-2.0, an Re of 2,000,000 and at angles of attack (AOA) of -4 to 20 deg. Measurements were made of lift, drag and pitching moments. Two linearized theory supersonic aerodynamic prediction codes, PAN AIR and the SDAS lift analysis, were used to predict the same aerodynamic coefficients. The fuselage AOA augmented the lift and pitching moment at 0, 2 and 5 deg. The contribution mainly arose from the fuselage-induced upwash. The PAN AIR code gave superior data for the fuselage aerodynamics and effects, although both codes accurately predicted the overall lift and moment increments due to the fuselage AOA.

Wood, R. M.↗

NASA NTRS2005

Gases and Aerosols over North America and the Atlantic: First results from INTEX-A

Intercontinental Chemical Transport Experiment (INTEX; http://cloud1.arc.nasa.gov) is an ongoing two-phase integrated atmospheric field experiment being performed over North America (NA). Its first phase (INTEX-A) was performed in the summer of 2004 and the second phase (INTEX-B) is planned for the early spring of 2006. The main goal is to characterize the sources and distribution of gases and aerosols over NA and to understand their transport and transformation on transcontinental/intercontinental scales in order to assess their impact on air quality and climate. Central to achieving this goal is the need to relate space-based observations with those from airborne and surface platforms. During JNTEX-A, NASA s DC-8 was joined by some dozen other aircraft from a large number of European (U. K., France, and Germany) and North American partners to explore the composition of the troposphere over NA and the Atlantic in a coordinated manner. Global and regional models along with satellite observations were extensively used to plan, coordinate, and implement this field mission. Aircraft were instrumented to measure a comprehensive suite of gases and aerosols utilizing in-situ and remote sensors. The NASA DC-8 alone was equipped with some 20 instruments capable of measuring species at concentrations as low as 10(exp -15) v/v. Measurements included major atmospheric gaseous constituents (O3, NO(x), HNO3, HNO4, PANS, SO2, VOC/OVOC, CO, and CO2), free radicals and precursors (OH, HO2, H2O2, HCHO), aerosols and radiation (microphysics, composition, optical depth, radiative flux), as well as multiple tracers of pollution. Validation of instruments aboard Terra, Aqua, and Envisat satellites was given high priority. Some of the highest pollution levels were present in the upper troposphere due to widespread deep convection. Although unexpected, frequent instances of Asian pollution over NA were encountered during these summer months. The soil uptake of CO2 over NA was characterized over large regions of NA helping to understand the continents CO2-sink potential. DC-8 sampling of smoke from Alaskan fires and formaldehyde over forested regions, and simultaneous satellite observations of these provided excellent opportunities for the interplay of these platforms. Outflow of pollution from NA was sampled again over the Atlantic after several days to assess its evolution during transport. Models of chemistry and radiation are presently being employed to help in the interpretation of JNTEX-A data. The planning for INTEX-B (spring 2006) is currently underway. First results from INTEX-A and plans for INTEX-B will be discussed

Singh, Hanwant B.↗

NASA NTRS2005

Solar System Visualizations

Solar System Visualization products enable scientists to compare models and measurements in new ways that enhance the scientific discovery process, enhance the information content and understanding of the science results for both science colleagues and the public, and create.visually appealing and intellectually stimulating visualization products. Missions supported include MER, MRO, and Cassini. Image products produced include pan and zoom animations of large mosaics to reveal the details of surface features and topography, animations into registered multi-resolution mosaics to provide context for microscopic images, 3D anaglyphs from left and right stereo pairs, and screen captures from video footage. Specific products include a three-part context animation of the Cassini Enceladus encounter highlighting images from 350 to 4 meter per pixel resolution; Mars Reconnaissance Orbiter screen captures illustrating various instruments during assembly and testing at the Payload Hazardous Servicing Facility at Kennedy Space Center; and an animation of Mars Exploration Rover Opportunity's 'Rub al Khali' panorama where the rover was stuck in the deep fine sand for more than a month. This task creates new visualization products that enable new science results and enhance the public's understanding of the Solar System and NASA's missions of exploration.

Brown, Alison M.↗

NASA NTRS2015

Upper Stage Engine Composite Nozzle Extensions

Carbon-carbon (C-C) composite nozzle extensions are of interest for use on a variety of launch vehicle upper stage engines and in-space propulsion systems. The C-C nozzle extension technology and test capabilities being developed are intended to support National Aeronautics and Space Administration (NASA) and United States Air Force (USAF) requirements, as well as broader industry needs. Recent and on-going efforts at the Marshall Space Flight Center (MSFC) are aimed at both (a) further developing the technology and databases for nozzle extensions fabricated from specific CC materials, and (b) developing and demonstrating low-cost capabilities for testing composite nozzle extensions. At present, materials development work is concentrating on developing a database for lyocell-based C-C that can be used for upper stage engine nozzle extension design, modeling, and analysis efforts. Lyocell-based C-C behaves in a manner similar to rayon-based CC, but does not have the environmental issues associated with the use of rayon. Future work will also further investigate technology and database gaps and needs for more-established polyacrylonitrile- (PAN-) based C-C's. As a low-cost means of being able to rapidly test and screen nozzle extension materials and structures, MSFC has recently established and demonstrated a test rig at MSFC's Test Stand (TS) 115 for testing subscale nozzle extensions with 3.5-inch inside diameters at the attachment plane. Test durations of up to 120 seconds have been demonstrated using oxygen/hydrogen propellants. Other propellant combinations, including the use of hydrocarbon fuels, can be used if desired. Another test capability being developed will allow the testing of larger nozzle extensions (13.5- inch inside diameters at the attachment plane) in environments more similar to those of actual oxygen/hydrogen upper stage engines. Two C-C nozzle extensions (one lyocell-based, one PAN-based) have been fabricated for testing with the larger-scale facility.

Valentine, Peter G.↗

NASA NTRS2006

2D/3D Visual Tracker for Rover Mast

A visual-tracker computer program controls an articulated mast on a Mars rover to keep a designated feature (a target) in view while the rover drives toward the target, avoiding obstacles. Several prior visual-tracker programs have been tested on rover platforms; most require very small and well-estimated motion between consecutive image frames a requirement that is not realistic for a rover on rough terrain. The present visual-tracker program is designed to handle large image motions that lead to significant changes in feature geometry and photometry between frames. When a point is selected in one of the images acquired from stereoscopic cameras on the mast, a stereo triangulation algorithm computes a three-dimensional (3D) location for the target. As the rover moves, its body-mounted cameras feed images to a visual-odometry algorithm, which tracks two-dimensional (2D) corner features and computes their old and new 3D locations. The algorithm rejects points, the 3D motions of which are inconsistent with a rigid-world constraint, and then computes the apparent change in the rover pose (i.e., translation and rotation). The mast pan and tilt angles needed to keep the target centered in the field-of-view of the cameras (thereby minimizing the area over which the 2D-tracking algorithm must operate) are computed from the estimated change in the rover pose, the 3D position of the target feature, and a model of kinematics of the mast. If the motion between the consecutive frames is still large (i.e., 3D tracking was unsuccessful), an adaptive view-based matching technique is applied to the new image. This technique uses correlation-based template matching, in which a feature template is scaled by the ratio between the depth in the original template and the depth of pixels in the new image. This is repeated over the entire search window and the best correlation results indicate the appropriate match. The program could be a core for building application programs for systems that require coordination of vision and robotic motion.

Bajracharya, Max↗

NASA NTRS1993

Simulation of summertime ozone over North America

The concentrations of O3 and its precursors over North America are simulated for three summer months with a 3D, continental-scale photochemical model using meteorological input from the Goddard Institute for Space Studies (GISS) GCM. The model has 4 x 5 deg grid resolution and represents nonlinear chemistry in urban and industrial plumes with a subgrid nested scheme. Simulated median afternoon O3 concentrations at rural U.S. sites are within 5 ppb of observations in most cases, except in the south central U.S., where concentrations are overpredicted by 15-20 ppb. The model captures successfully the development of regional high-O3 episodes over the northeastern United States on the back side of weak, warm, stagnant anticyclones. Simulated concentrations of CO and nonmethane hydrocarbons are generally in good agreement with observations, concentrations of NO(x) are underpredicted by 10-30 percent, and concentrations of PANs are overpredicted by a factor of 2 to 3. The overprediction of PANs is attributed to flaws in the photochemical mechanism, including excessive production from oxidation of isoprene, and may also reflect an underestimate of PANs deposition. Subgrid nonlinear chemistry as captured by the nested plumes scheme decreases the net O3 production computed in the U.S. boundary layer by 8 percent on average.

Jacob, Daniel J.↗

NASA NTRS2001

Airborne spectral Measurements of Surface-Atmosphere Anisotropy for Several Surfaces and Ecosystem over Southern Africa

The Cloud Absorption Radiometer (CAR) was flown aboard the University of Washington Convair CV-580 research aircraft and took measurements on 23 flights between August 15 and September 16. On 12 of those flights, BRF measurements were obtained over different natural surfaces and ecosystem in southern Africa. The BRF measurements were done to characterize surface anisotropy in support of SAFARI 2000 science objectives principally to validate products from NASA's EOS satellites, and to parameterize and validate BRF models. In this paper we present results of BRFs taken over two EOS validation sites: Skukuza tower, South Africa (25.0 deg S, 31.5 deg E) and Mongu tower, Zambia (15.4 deg S, 23.3 deg E). Additional sites are also considered and include, Maun tower, Botswana (20.0 deg S, 23.5 deg E), Sowa Pan, Botswana (20.6 deg S, 26.2 deg E) and Etosha Pan, Namibia (19.0 deg S, 16.0 deg E). The CAR is capable of measuring scattered light in fourteen spectral bands. The scan mirror, rotating at 100 rpm, directs the light into a Dall-Kirkham telescope where the beam is split into nine paths. Eight light beams pass through beam splitters, dichroics, and lenses to individual detectors (0.34-1.27 micrometers), and finally are registered by eight data channels. They are sampled simultaneously and continuously. The ninth beam passes through a spinning filter wheel to an InSb detector cooled by a Stirling cycle cooler. Signals registered by the ninth data channel are selected from among six spectral channels (1.55-2.30 micrometers). The filter wheel can either cycle through all six spectral bands at a prescribed interval (usually changing filter every fifth scan line), or lock onto any one of the six spectral bands and sample it continuously. To measure the BRF of the surface-atmosphere system, the University of Washington CV-580 had to bank at a comfortable roll angle of approximately 20 degrees and fly in a circle about 3 km in diameter above the surface for roughly two minutes. Replicated observations (multiple circular orbits) were acquired over selected surfaces so that average BRF smooth out small-scale surface and atmospheric inhomogeneities. At an altitude of 600 m above the targeted surface area and with a 1 deg IFOV, the pixel resolution is about 10 m at nadir and about 270 m at an 80 deg viewing angle from the CAR.

Gatebe, Charles K.↗

NASA NTRS1991

Properties of novel CVD graphite fibers and their bromine intercalation compounds

A hybrid fiber with a PAN core surrounded by a vapor grown carbon fiber (VGCF) sheath was fabricated using a proprietary process. The density, ultimate tensile strength, Young's modulus, and resistivity of pristine and bromine intercalated fibers made by this technique having diameters varying from 5 to 50 microns were compared with the values predicted from the rule of mixtures model. For both the pristine and intercalated fibers, the density, ultimate tensile strength, and Young's modulus of the fibers were lower than predicted, but the resistivity was measured to be consistent with predictions. The lower than theoretical mechanical properties may be evidence of a low density disordered interface between the core and the sheath which would lower the density and degrade the mechanical properties, but would leave the resistivity nearly unaffected. Intercalation had little if any effect on the ultimate tensile strength and Young's modulus, but raised the density by about 11 pct., and lowered the resistivity by an order of magnitude. The diameter dependence of the resistivity showed evidence of a depletion layer of the type found in VGCF.

Gaier, James R.↗

NASA NTRS1991

Strontium isotopic variations of Neoproterozoic seawater - Implications for crustal evolution

High-precision Sr isotopic data were obtained on carbonate samples from the Neoproterozoic Shaler Group, Victoria Island (Canada). Results indicate that, between ca. 790 and 850 Ma, the Sr-87/Sr-86 ratio of seawater varied betweeen 0.70676 and 0.70561, with the minimum value at about 830 Ma. A curve of the Sr-87/Sr-86 seawater ratio vs. age showed that the new data substantially improve the existing isotopic record of Sr in seawater for the period 790-850 Ma. The Sr isotopic system data were coupled with data for the Nd isotopic system to model changes in the seafloor spreading rates (hydrothermal flux) and the continental erosion for the period 500-900 Ma. Results indicate that hydrothermal flux reached a maximum value at ca. 830 Ma, while a maximum in erosion rate occurred at ca. 570 Ma. These peaks are considered to be related to the developments in the Pan-African and related orogenic events.

Asmerom, Yemane↗

NASA NTRS1992

Properties of hybrid CVD/PAN graphite fibers and their bromine intercalation compounds

Gaier, James R.↗

NASA NTRSDate not supplied

Update on AeroCom Biomass Burning Emission Injection Height experiment (BBEIH)

In BBEIH, we introduced the biomass burning injection heights based on MISR stereo-derived plume-height retrievals (Val Martin et al., 2010; 2018) in four participating CTMs. Specifically, we proposed 4 simulations for the year 2008: 1) BASE: using the biomass burning emissions from Global Fire Emissions Database version 4 with small ﬁres (GFED4s) and the model default fire emission injection height; 2) BBIH: Same as BASE, but using the injection height derived from the seasonally and regionally varying MISR-retrieved plume heights; 3) NOBB: no fire emission; 4) Same as BASE, but using Fire Energetics and Emissions Research version 1.0 (FEER 1.0). We will address the following scientific questions: 1) To what extent are the model simulations sensitive to the assumed biomass burning injection height? 2) In which regions/seasons/surface-types are the aforementioned sensitivities most important? We will update the multi-model inter-comparison with a focus on the vertical aerosol distribution in near-source characteristics and downwind plume evolution." In order to test the sensitivity of model results to smoke injection height, we proposed the biomass burning emission injection height experiment (BBEIH) in the AeroCom 2019 workshop. The description of implementation methods and input data for BBEIH can be found in https://wiki.met.no/aerocom/phase3-experiments#biomass_burning_emission_injection_height_experiment_bbeih.

Xiaohua Pan↗

NASA NTRS2007

Summertime Influence of Asian Pollution in the Free Troposphere over North America

We analyze aircraft observations obtained during INTEX-A (1 July 14 - August 2004) to examine the summertime influence of Asian pollution in the free troposphere over North America. By applying correlation analysis and Principal Component Analysis (PCA) to the observations between 6-12 km, we find dominant influences from recent convection and lightning (13 percent of observations), Asia (7 percent), the lower stratosphere (7 percent), and boreal forest fires (2 percent), with the remaining 71 percent assigned to background. Asian airmasses are marked by high levels of CO, O3, HCN, PAN, acetylene, benzene, methanol, and SO4(2-). The partitioning of reactive nitrogen species in the Asian plumes is dominated by peroxyacetyl nitrate (PAN) (approximately 600 pptv), with varying NO(x)/HNO3 ratios in individual plumes consistent with different plumes ages ranging from 3 to 9 days. Export of Asian pollution in warm conveyor belts of mid-latitude cyclones, deep convection, and lifting in typhoons all contributed to the five major Asian pollution plumes. Compared to past measurement campaigns of Asian outflow during spring, INTEX-A observations display unique characteristics: lower levels of anthropogenic pollutants (CO, propane, ethane, benzene) due to their shorter summer lifetimes; higher levels of biogenic tracers (methanol and acetone) because of a more active biosphere; as well as higher levels of PAN, NO(x), HNO3, and O3 (more active photochemistry possibly enhanced by injection of lightning NO(x)). The high delta O3/delta CO ratio (0.76 mol mol(exp -1)) of Asian plumes during INTEX-A is due to a combination of strong photochemical production and mixing with stratospheric air along isentropic surfaces. The GEOS-Chem global chemical transport model captures the timing and location of the Asian plumes remarkably well. However, it significantly underestimates the magnitude of the enhancements.

Liang, Q.↗

NASA NTRS1983

Low-noise 115-GHz receiver using superconducting tunnel junctions

A 110-118-GHz receiver based on a superconducting quasiparticle tunnel junction mixer is described. The single-sideband noise temperature is as low as 68 + or - 3 K. This is nearly twice the sensitivity of any other receiver at this frequency. The receiver was designed using a low-frequency scale model in conjunction with the quantum mixer theory. A scaled version of the receiver for operation at 46 GHz has a single-sideband noise temperature of 55 K. The factors leading to the success of this design are discussed.

Pan, S.-K.↗

NASA NTRS2011

Satellite-Derived Distributions, Inventories and Fluxes of Dissolved and Particulate Organic Matter Along the Northeastern U.S. Continental Margin

Estuaries and the coastal ocean experience a high degree of variability in the composition and concentration of particulate and dissolved organic matter (DOM) as a consequence of riverine and estuarine fluxes of terrigenous DOM, sediments, detritus and nutrients into coastal waters and associated phytoplankton blooms. Our approach integrates biogeochemical measurements, optical properties and remote sensing to examine the distributions and inventories of organic carbon in the U.S. Middle Atlantic Bight and Gulf of Maine. Algorithms developed to retrieve colored DOM (CDOM), Dissolved (DOC) and Particulate Organic Carbon (POC) from NASA's MODIS-Aqua and SeaWiFS satellite sensors are applied to quantify the distributions and inventories of DOC and POC. Horizontal fluxes of DOC and POC from the continental margin to the open ocean are estimated from SeaWiFS and MODIS-Aqua distributions of DOC and POC and horizontal divergence fluxes obtained from the Northeastern North Atlantic ROMS model. SeaWiFS and MODIS imagery reveal the importance of estuarine outflow to the export of CDOM and DOC to the coastal ocean and a net community production of DOC on the shelf.

Mannino, A.↗

NASA NTRS2014

Modeling Approaches in Planetary Seismology

Of the many geophysical means that can be used to probe a planet's interior, seismology remains the most direct. Given that the seismic data gathered on the Moon over 40 years ago revolutionized our understanding of the Moon and are still being used today to produce new insight into the state of the lunar interior, it is no wonder that many future missions, both real and conceptual, plan to take seismometers to other planets. To best facilitate the return of high-quality data from these instruments, as well as to further our understanding of the dynamic processes that modify a planet's interior, various modeling approaches are used to quantify parameters such as the amount and distribution of seismicity, tidal deformation, and seismic structure on and of the terrestrial planets. In addition, recent advances in wavefield modeling have permitted a renewed look at seismic energy transmission and the effects of attenuation and scattering, as well as the presence and effect of a core, on recorded seismograms. In this chapter, we will review these approaches.

Weber, Renee↗