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  • Lunar and Planetary Science and Exploration  (1,839)
  • Spacecraft Design, Testing and Performance  (864)
  • Geophysics  (667)
  • Aerodynamics
  • General Chemistry
  • Inorganic Chemistry
  • Life and Medical Sciences
  • 2005-2009  (3,708)
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  • 1
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    WSEAS Press
    Publication Date: 2017-04-04
    Description: For Geosystemics we define the science that studies the Earth system from a holistic point of view. Earth is thus considered as a whole and unique far-from-the equilibrium complex system, formed by numerous different parts (sub-systems), which do not act independently but interact each other continuously. Most interactions are nonlinear, so that we can usually say that “resultant is more than the sum of the parts”. Interactions are not only in terms of contrasts but, and mostly, cooperative and mutual organizations. We will see some aspects and properties of this approach with a few examples.
    Description: Published
    Description: Cambridge, UK, February 24-26, 2009
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: open
    Keywords: Geosystemics ; Earth system ; Nonlinear Analysis ; Entropy ; Geophysics ; 03. Hydrosphere::03.03. Physical::03.03.01. Air/water/earth interactions ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 2
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    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2001
    Description: Half of the ocean crust is formed at spreading centers with total opening rates less than 40 km/Myr. The objective of this Thesis is to investigate temporal variations in active ridge processes and crustal aging at slow-spreading centers by comparing axial crustal structure with that on conjugate flanks of the slow-spreading Mid-Atlantic Ridge (MAR) (full rate, 20 km/Myr) and the ultra-slow spreading Southwest Indian Ridge (SWIR) (full rate, 14 km/Myr). Seismic refraction data collected along the rift valley and flanking rift mountains of the OH-l segment (35°N) at the MAR show that the entire crustal section is constructed within a zone that is less than 5 km wide. Shallow-level hydrothermal circulation within the axial valley is suggested by the rift mountain seismic profiles, which show that the upper crust is 20% thinner and 16% faster along strike than zero-age crust. These effects probably result from fissure sealing within the extrusive crust. Deeper crustal velocities remain relatively constant at the segment midpoint within the first 2 Myr, but are reduced near the segment offsets presumably by faulting and fracturing associated with uplift out of the rift valley. A temporal variation in axial melt supply is suggested by a 15% difference in along-strike crustal thickness between the rift valley and rift mountains, with relatively less melt supplied today than 2 Ma. Crustal accretion at the SWIR appears to occur in a similar manner as at the MAR, although gravity and seismic data indicate that the average crustal thickness is 2-4 km less at the ultra-slow spreading SWIR. A 25 Myr record on both flanks of the ridge shows that seafloor spreading has been highly asymmetric through time, with 35% faster crustal accretion on the Antarctic (south) plate. A small-offset non-transform discontinuity between two ridge segments is just as stable as two neighboring transform discontinuities, although a single mantle Bouguer gravity anomaly centered over the non-transform offset indicates that this boundary does not significantly perturb underlying mantle flow. Off-axis magnetic anomalies are recorded with high fidelity despite the very low spreading rates and the absence of a basaltic upper crust in one area. The lower crust may be the dominant off-axis carrier of the magnetic signal, contrary to traditional models of crustal magnetic structure. Morphological and gravity data show evidence of asymmetric crustal accretion across the SWIR ridge axis, with slightly warmer mantle temperatures beneath the slower-spreading African (north) plate.
    Description: Funding was provided by the National Science Foundation through Contract No. OCE-9300450 and by the Joint Oceanographic Institutions through Subcontract No. JSC1-00.
    Keywords: Earth ; Crust ; Geophysics ; Maurice Ewing (Ship) Cruise EW96-08 ; Yokosuka (Ship) Cruise ; Kairei (Ship) Cruise ; Conrad (Ship) Cruise RC2709
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 3
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 60-46, series later renamed WHOI-.
    Description: National Science Foundation under Research Grant NSF 12556
    Keywords: Geophysics ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 4
    Publication Date: 2022-05-26
    Description: The (Lagrangian) motion of a fluid particle was contrasted with the (Eulerian) flow past a fixed point in space during this twenty-fourth summer program in geophysical fluid dynamics at the Woods Hole Oceanographic Institution.
    Description: Office of Naval Research under Contract N00014-82-G-0079 and National Science Foundation Grant MCS-82-00450. Partial support from the Center for Analysis of Marine Systems (CAMS) at Woods Hole Oceanographic Institution.
    Keywords: Geophysics ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 5
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 60-46, series later renamed WHOI-.
    Description: This ten-week work-study-discussion program is centered about a formal course called Geophysical Fluid Dynamics. Eight participants are selected from graduate and postgraduate applicants. In the discussions emphasis is placed on the formulation of tractable research problems in geophysics. The participants are encouraged to work on satisfactory problems thus formulated and to continue with their research after returning to their respective institutions.
    Description: National Science Foundation under Research Grant NSF 12556
    Keywords: Geophysics ; Fluid models ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 6
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 59-53, series later renamed WHOI-.
    Description: This ten-week work-study-discussion program is centered about a formal course called Geophysical Fluid Dynamics. Eight participants are selected from graduate and postgraduate applicants. In the discussions emphasis is placed on the formulation of tractable research problems in geophysics. The participants are encouraged to work on satisfactory problems thus formulated and to continue with their research after returning to their respective institutions.
    Description: National Science Foundation under Research Grant NSF G-9125
    Keywords: Fluid dynamics ; Geophysics ; Fluid models
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 7
    Publication Date: 2022-05-26
    Description: Originally issued as Reference no. 61-39, series later renamed WHOI-.
    Description: National Science Foundation under Research Grant NSF G-16973
    Keywords: Geophysics ; Fluid models ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 8
    Publication Date: 2022-05-26
    Description: Four principal lecturers shored the task of presenting the subject "Coherent Features in Geophysical Flows" to the participants of the twenty-second geophysical fluid dynamics summer program. Glenn Flierl introduced the topic and the Kortweg-de Vries equation via a model of finite amplitude motions on the beta plane. He extended the analysis to more complex flows in the ocean and the atmosphere and in the process treated motions of very large amplitude. Larry Redekopp's three lectures summarized an extensive body of the mathematical literature on coherent features. Andrew Ingersoll focussed on the many fascinating features in Jupiter's atmosphere. Joseph Keller supplemented an interesting summary of laboratory observations with suggestive models for treating the flows.
    Description: Office of Naval Research under Contract N00014-79-C-0671
    Keywords: Geophysics ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 9
    Publication Date: 2022-05-26
    Description: Those attending G.F.D. 1984 were introduced to the novel topic of Geological Fluid Mechanics by our Principal Lecturer, Herbert Huppert. He presented his studies both as a discipline with recent fascinating successes, and as a challenge to his listeners to further isolate mathematically tractable examples of these multi-component flows. Geological Fluid Mechanics has been the responsible process for the formation and modification of most of the geological objects studied today. The dynamics of fluid mixtures in magma chambers, the changing fluid boundary conditions and composition during selective crystallization of parts of the melt, and the separation of fluid fractions of different density and viscosity all represent areas in which quantitative theories are currently being tested. However, equally many areas, including convection mechanisms in the Earth's core and quantitative predictions for upper mantle motion, resist simplistic modeling.
    Description: Office of Naval Research under contract N00014-82-G-0079 and the National Science Foundation under Grant MCS-82-800450. Partial support acknowledged from the Center for Anatysis of Marine Systems (CAMS) at the Woods Hole Oceanographic Institution. CAMS is supported by The Exxon Foundation, Mobil Foundation, Inc., The Ambrose Monell Foundation, The R. R. Mellon Family Foundation., the Atlantic Richfield Foundation, and by an anonymous donor.
    Keywords: Geophysics ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
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  • 10
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: The explosive growth of dynamieal systems theory in the past two decades stems in large part from the realization that it is applicable to many natural phenomena. Indeed, much o f the theoretical development has been sparked by numerical and laboratory experiments which exhibit ordered sequences of behavior that call for a general framework of interpretation We have been fortunate this summer to have had in residence both pioneers and developers of dynamical systems theory and its applications to fluid mechanics. Several recent texts contain the basic principles that Ed Spiegel used as a springboard for five lectures in which he exposed us to elementary examples of bifurcation and chaos, to symmetry breaking, normal forms and temporal and spatial disorder, as well as to pertinent fluid mechanical and astrophysical phenomena. Yves Pomeau continued the development with an elegant summary of different types of intermittency . Stephan Fauve agree to write up his impressive seminars on phase instability and turbulence as an extension of the lecture series. Many of the remaining seminars introduced new concepts in the theory, some with specific examples, others via mathematical development, and still others through ways of interpreting the data that emerge from calculations and experiments. As an outstanding example of this, Albert Libchaber has demonstrated the fascinating correspondence between the frequencies observed in one of his recent fluid mechanics experiments and results from number theory relating the Fibonacci series to the golden mean.
    Description: Office of Naval Research under contract NO0014-82-6-0079 and the National Science Foundation under Grants MCS-82-000450 and DMS-85-04166.
    Keywords: Geophysics ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 11
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 63-34, series later renamed WHOI-.
    Description: This year's lectures by Derek Moore form a detailed report of investigations on the fluid motion caused by the motion of a body in a homogeneous rotating fluid. The emphasis has been on the significance of the Taylor-Proudman theorem and the departure of the fluid from the behavior described by the Taylor-Proudman theorem. The plan was to probe deeply into one problem and thereby acquire information in a wider area of study of rotating fluids.
    Description: National Science Foundation under Research Grant NSF GE-15l8
    Keywords: Geophysics
    Repository Name: Woods Hole Open Access Server
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  • 12
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 66-46, series later renamed WHOI-.
    Description: The lecturers, Drs. Howard, Stern and Veronis, have introduced the participants to several aspects of geophysical fluid dynamics at the frontiers of current research. Their choice of topic and its development was to serve, on one hand, a pedagogic function and, on the other, to suggest a variety of allied unsolved problems.
    Description: National Science Foundation
    Keywords: Geophysics
    Repository Name: Woods Hole Open Access Server
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  • 13
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 65-51, series later renamed WHOI-.
    Description: National Science Foundation
    Keywords: Geophysics
    Repository Name: Woods Hole Open Access Server
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  • 14
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 68-72, series later renamed WHOI-.
    Description: The general circulation of the oceans was the topic of concentration for the 1968 WHOI Summer Program in Geophysical Fluid Dynamics
    Description: National Science Foundation
    Keywords: Ocean circulation ; Geophysics ; Fluid models
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 15
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 69-41, series later renamed WHOI-.
    Description: The principal theme of this eleventh Summer Program has been Astrophysical Fluid Dynamics. As in the past, we have explored the region of overlap in technique and theory of our summer theme and other aspects of Fluid Dynamics. An interesting example of this overlap is the application of the physics of salt-finger instability, a significant oceanographic process, to instabilities due to differential rotation in the sun, a critical problem in stellar evolution.
    Description: National Science Foundation
    Keywords: Geophysics ; Ocean circulation
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 16
    Publication Date: 2022-05-26
    Description: The central topic of this seventeenth Geophysical Fluid Dynamics program was fluid motion in the earth's mantle and core. Our principal lecturer, Dan McKenzie, first addressed himself to the task of separating solid behavior of the mantle from fluid behavior. When the level of protest diminished Dan advanced to his numerical studies of mantle convection. The relationship of these numerical experiments and geophysical observables was impressive indeed for this first generation of mantle modeling. Intertwined seminars from P. Molnar, B. Parsons, J. Sclater and T. Atwater exposed us to data gathering and its rationale at the frontiers of geophysics. The fluid properties of the core may be less suspect than those of the mantle, but how and why the core fluid moves is still a mystery. Our associate principal lecturer, Fritz Busse, discussed the geomagnetic evidence for core motion. Then moving quickly to the more abstract problems of model geodynamos, Fritz described in five lectures his achievement of a first complete dynamic dynamo driven by convection.
    Description: National Science Foundation
    Keywords: Geophysics
    Repository Name: Woods Hole Open Access Server
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  • 17
    Publication Date: 2022-05-26
    Description: This was the twentieth Geophysical Fluid Dynamics program at Woods Hole. Stephen Childress of the Courant Institute was our principal lecturer. Dynamo theory, with all its interdisciplinary facets was our central theme. Geomagnetism and the solar magnetic cycle were brought closer to comprehension, yet none claimed a detailed predictive theory was near at hand. Perhaps J. Keller's lecture, entitled "Smooth equations for rough problems", best characterized the nature of these studies. Even then, the smooth equations are quite nonlinear, with Finite-amplitude magnetic solutions yet to be explored. Lectures intertwined with those of Childress exposed us to topics beside and outside his emphasis on a convective geodynamo.
    Description: Office of Naval Research under Contract N00014-78-G0072
    Keywords: Geophysics ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
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  • 18
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 61-39, series later renamed WHOI-.
    Description: This ten-week work-study-discussion program was centered about a formal course called Geophysical Fluid Dynamics. Sixteen participants were selected from graduate and postgraduate applicants. In the discussions emphasis was placed on the formulation of tractable research problems in geophysics. The participants were encouraged to work on satisfactory problems thus formulated and to continue with their research after returning to their respective institutions.
    Description: National Science Foundation under Research Grant NSF G-16973
    Keywords: Geophysics ; Fluid models ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
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  • 19
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 62-33, series later renamed WHOI-.
    Description: National Science Foundation under Research Grant NSF22332
    Keywords: Geophysics ; Fluid dynamics
    Repository Name: Woods Hole Open Access Server
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  • 20
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 62-38, series later renamed WHOI-.
    Description: Includes the preprint "Mixing-length Analyses of Turbulent Thermal Convection at Arbitrary Prandtl Number" - R. Kraichnan (1962). N.Y.U. Research Report No. HSN-6.
    Description: National Science Foundation under Research Grant NSF22332
    Keywords: Geophysics ; Fluid dynamics
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  • 21
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 64-46, series later renamed WHOI-.
    Description: Two distinctive features of large-scale geophysical flows are that they are dominated by the earth's rotation and that they are turbulent. This year's lecture program was an exploration of recent achievements in the study of, first, the simplest examples of turbulence, and second, the rotational constraint.
    Description: National Science Foundation and Travelers' Research Center, Inc
    Keywords: Geophysics
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  • 22
    Publication Date: 2022-05-26
    Description: Nonlinear wave interactions formed the theme of the fifteenth summer program in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution. Owen Phillips was our principal lecturer on this subject, He chose to emphasize interactions among small numbers of discrete wave modes, including both internal and surface gravity waves in his discussions. His lectures provided a stimulating introduction to this important subject. Phillips' lectures were supplemented by a lecture by William Simmons on experiments with interacting internal waves, and a lecture by Carl Wunsch on internal waves in the ocean. Later in the summer, Wunsch gave us a lecture series on practical time-series analysis.
    Description: We thank the National Science Foundation for their continuing support.
    Keywords: Geophysics ; Fluid models
    Repository Name: Woods Hole Open Access Server
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  • 23
    Publication Date: 2022-05-26
    Description: The effect of gravity on fluids of varying density is of fundamental importance in natural flows. This subject formed the topic of concentration for the fourteenth summer program in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution. We had the good fortune to hear Stewart Turner lecture on stratified flows just after he had completed the manuscript for his book on the subject. Turner chose to emphasize nonlinear and turbulent aspects of stratified flows and, therefore, had to give up the deductive approach in favor of treatments based on dimensional analysis and similarity arguments. This summary of the many experimental studies of these flows increased our awareness of the fascinating variety of phenomena in which stratification plays so vital a role.
    Description: Supported by the Division of Fluid Dynamics, Oceanography and Applied Mathematics of the Office of Naval Research.
    Keywords: Geophysics
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  • 24
    Publication Date: 2022-05-26
    Description: This year the central topic was the general circulation of the oceans. Some of the basic ideas used in wind-driven and thermohaline studies were presented in the introductory course of lectures and simple models that have guided our thinking in the development of the topic were discussed. As part of the introductory lectures Peter Niiler developed a model of the mixed layer, exploring the reasoning and the parameterization behind the theories of this important boundary region at the surface of the ocean. Dennis Moore gave a careful account of transient flows in equatorial regions and showed how dynamical conditions on the eastern and western boundaries are satisfied by a superposition of planetary, Kelvin and Yanai waves. Peter Rhines concluded the series with a discussion of topographically induced low frequency motions. At the request of the students Joseph B. Keller gave a lecture on "Solution of Partial Differential Equations by Ray Theory".
    Description: National Science Foundation
    Keywords: Geophysics
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  • 25
    Publication Date: 2013-04-10
    Description: This presentation reviews the International Lunar Network (ILN) mission, a cooperative effort designed to coordinate individual lunar landers in a geophysical network on the lunar surface. The presentation also includes information on the geophysical network, mission operations, and recent accomplishments.
    Keywords: Lunar and Planetary Science and Exploration
    Type: M09-0817 , NLSI Lunar Science Forum; 21-23 Jul. 2009; Moffett Field, CA; United States
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  • 26
    Publication Date: 2018-06-06
    Description: Amino acid analysis of a meteorite fragment of asteroid 2008 TC(sub 3) called Almahata Sitta was carried out using reverse-phase high-perfo rmance liquid chromatography coupled with UV fluorescence detection a nd time-of-flight mass spectrometry (HPLC-FD/ToF-MS) as part of a sam ple analysis consortium. HPLC analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to six-carbon aliph atic amino acids and one- to three carbon amines with abundances rang ing from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, Beta-amino-n-butyric acid (Beta-ABA), 2-amino-2- methylbutanoic acid (isovaline), and 2-aminopentanoic acid (no rvaline) in the meteorite were racemic (D/L approximately 1), indicat ing that these amino acids are indigenous to the meteorite and not te rrestrial contaminants. Several other non-protein amino acids were also identified in the meteorite above background levels including alpha -aminoisobutyric acid (alpha-AIB), 4-amino-2- methybutanoic acid, 4-a mino-3-methylbutanoic acid, and 3-, 4-, and 5-aminopentanoic acid. Th e total abundances of isovaline and AlB in Almahata Sitta are approximately 1000 times lower than the abundances of these amino acids found in the CM carbonaceous meteorite Murchison. The extremely love abund ances and unusual distribution of five carbon amino acids in Almahata Sitta compared to Cl, CM, and CR carbonaceous meteorites and may be due to extensive thermal alteration of amino acids on the parent aster oid by partial melting during formation or impact shock heating.
    Keywords: Lunar and Planetary Science and Exploration
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  • 27
    Publication Date: 2018-06-06
    Description: The distribution and enantiomeric composition of the 5-carbon (C(sub 5)) amino acids found in Cl-, CM-, and CR-type carbonaceous meteorites were investigated by using liquid chromatography fluorescence detection/TOF-MS coupled with o-phthaldialdehyde/Nacetyl- l-cysteine derivatization. A large L-enantiomeric excess (ee) of the a-methyl amino acid isovaline was found in the CM meteorite Murchison (L(sub ee) = 18.5 +/- 2.6%) and the Cl meteorite Orguell (L(sub ee) = 15.2 +/- 4.0%). The measured value for Murchison is the largest enantiomeric excess in any meteorite reported to date, and the Orgueil measurement of an isovaline excess has not been reported previously for this or any Cl meteorite. The L-isovaline enrichments in these two carbonaceous meteorites cannot be the result of interference from other C(sub 5) amino acid isomers present in the samples, analytical biases, or terrestrial amino acid contamination. We observed no L-isovaline enrichment for the most primitive unaltered Antarctic CR meteorites EET 92042 and QUE 99177. These results are inconsistent with UV circularly polarized light as the primary mechanism for L-isovaline enrichment and indicate that amplification of a small initial isovaline asymmetry in Murchison and Orgueil occurred during an extended aqueous alteration phase on the meteorite parent bodies. The large asymmetry in isovaline and other alpha-dialkyl amino acids found in altered Ct and CM meteorites suggests that amino acids delivered by asteroids, comets, and their fragments would have biased the Earth's prebiotic organic inventory with left-handed molecules before the origin of life.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Proceedings of the National Academy of Sciences of the United States of America (PNAS); Volume 106; No. 14; 5487-5492
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  • 28
    Publication Date: 2018-06-06
    Description: We present the mass X-ray observable scaling relationships for clusters of galaxies using the XMM-Newton cluster catalog of Snowden et al. Our results are roughly consistent with previous observational and theoretical work, with one major exception. We find 2-3 times the scatter around the best fit mass scaling relationships as expected from cluster simulations or seen in other observational studies. We suggest that this is a consequence of using hydrostatic mass, as opposed to virial mass, and is due to the explicit dependence of the hydrostatic mass on the gradients of the temperature and gas density profiles. We find a larger range of slope in the cluster temperature profiles at radii 500 than previous observational studies. Additionally, we find only a weak dependence of the gas mass fraction on cluster mass, consistent with a constant. Our average gas mass fraction results also argue for a closer study of the systematic errors due to instrumental calibration and modeling method variations between analyses. We suggest that a more careful study of the differences between various observational results and with cluster simulations is needed to understand sources of bias and scatter in cosmological studies of galaxy clusters.
    Keywords: Lunar and Planetary Science and Exploration
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  • 29
    Publication Date: 2018-06-06
    Description: The direct and semi-direct effects of aerosols produced by Indonesian biomass burning (BB) during August November 2006 on tropical dynamics have been examined using NASA's Goddard Earth Observing System, Version 5 (GEOS-5) atmospheric general circulation model (AGCM). The AGCM includes CO, which is transported by resolved and sub-grid processes and subject to a linearized chemical loss rate. Simulations were driven by two sets of aerosol forcing fields calculated offline, one that included Indonesian BB aerosol emissions and one that did not. In order to separate the influence of the aerosols from internal model variability, the means of two ten-member ensembles were compared. Diabatic heating from BB aerosols increased temperatures over Indonesia between 150 and 400 hPa. The higher temperatures resulted in strong increases in upward grid-scale vertical motion, which increased water vapor and CO over Indonesia. In October, the largest increases in water vapor were found in the mid-troposphere (~25%) while the largest increases in CO occurred just below the tropopause (80 ppbv or ~50%). Diabatic heating from the Indonesian BB aerosols caused CO to increase by 9% throughout the tropical tropopause layer in November and 5% in the lower stratosphere in December. The results demonstrate that aerosol heating plays an important role in the transport of BB pollution and troposphere-to-stratosphere transport. Changes in vertical motion and cloudiness induced by aerosol heating can also alter the transport and phase of water vapor in the upper troposphere/lower stratosphere.
    Keywords: Geophysics
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  • 30
    Publication Date: 2018-06-06
    Description: We used the seasonality of a combination of atmospheric trace gases and idealized tracers to examine stratosphere-to-troposphere transport and its influence on tropospheric composition in the Arctic. Maximum stratosphere-to-troposphere transport of CFCs and O3 occurs in April as driven by the Brewer-Dobson circulation. Stratosphere-troposphere exchange (STE) occurs predominantly between 40 deg N to 80 deg N with stratospheric influx in the mid-latitudes (30-70 deg N) accounting for 67.81 percent of the air of stratospheric origin in the Northern Hemisphere extratropical troposphere. Transport from the lower stratosphere to the lower troposphere (LT) takes three months on average, one month to cross the tropopause, the second month to travel from the upper troposphere (UT) to the middle troposphere (MT), and the third month to reach the LT. During downward transport, the seasonality of a trace gas can be greatly impacted by wet removal and chemistry. A comparison of idealized tracers with varying lifetimes suggests that when initialized with the same concentrations and seasonal cycles at the tropopause, trace gases that have shorter lifetimes display lower concentrations, smaller amplitudes, and earlier seasonal maxima during transport to the LT. STE contributes to O3 in the Arctic troposphere directly from the transport of O3 and indirectly from the transport of NOy . Direct transport of O3 from the stratosphere accounts for 78 percent of O3 in the Arctic UT with maximum contributions occurring from March to May. The stratospheric contribution decreases significantly in the MT/LT (20.25 percent of total O3) and shows a very weak March.April maximum. Our NOx budget analysis in the Arctic UT shows that during spring and summer, the stratospheric injection of NO y-rich air increases NOx concentrations above the 20 pptv threshold level, thereby shifting the Arctic UT from a regime of net photochemical ozone loss to one of net production with rates as high as +16 ppbv/month.
    Keywords: Geophysics
    Type: Atmospheric Chemistry and Physics; Volume 9; 3011-2025
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  • 31
    Publication Date: 2018-06-06
    Description: Gross primary production (GPP) is a key terrestrial ecophysiological process that links atmospheric composition and vegetation processes. Study of GPP is important to global carbon cycles and global warming. One of the most important of these processes, plant photosynthesis, requires solar radiation in the 0.4-0.7 micron range (also known as photosynthetically active radiation or PAR), water, carbon dioxide (CO2), and nutrients. A vegetation canopy is composed primarily of photosynthetically active vegetation (PAV) and non-photosynthetic vegetation (NPV; e.g., senescent foliage, branches and stems). A green leaf is composed of chlorophyll and various proportions of nonphotosynthetic components (e.g., other pigments in the leaf, primary/secondary/tertiary veins, and cell walls). The fraction of PAR absorbed by whole vegetation canopy (FAPAR(sub canopy)) has been widely used in satellite-based Production Efficiency Models to estimate GPP (as a product of FAPAR(sub canopy)x PAR x LUE(sub canopy), where LUE(sub canopy) is light use efficiency at canopy level). However, only the PAR absorbed by chlorophyll (a product of FAPAR(sub chl) x PAR) is used for photosynthesis. Therefore, remote sensing driven biogeochemical models that use FAPAR(sub chl) in estimating GPP (as a product of FAPAR(sub chl x PAR x LUE(sub chl) are more likely to be consistent with plant photosynthesis processes.
    Keywords: Geophysics
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  • 32
    Publication Date: 2018-06-06
    Description: The Global Land Survey (GLS) 2005 is a cloud-free, orthorectified collection of Landsat imagery acquired during the 2004-2007 epoch intended to support global land-cover and ecological monitoring. Due to the numerous complexities in selecting imagery for the GLS2005, NASA and the U.S. Geological Survey (USGS) sponsored the development of an automated scene selection tool, the Large Area Scene Selection Interface (LASSI), to aid in the selection of imagery for this data set. This innovative approach to scene selection applied a user-defined weighting system to various scene parameters: image cloud cover, image vegetation greenness, choice of sensor, and the ability of the Landsat 7 Scan Line Corrector (SLC)-off pair to completely fill image gaps, among others. The parameters considered in scene selection were weighted according to their relative importance to the data set, along with the algorithm's sensitivity to that weight. This paper describes the methodology and analysis that established the parameter weighting strategy, as well as the post-screening processes used in selecting the optimal data set for GLS2005.
    Keywords: Geophysics
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  • 33
    Publication Date: 2018-06-06
    Description: The Soil Moisture Experiments conducted in Iowa in the summer of 2002 (SMEX02) had many remote sensing instruments that were used to study the spatial and temporal variability of soil moisture. The sensors used in this paper (a subset of the suite of sensors) are the AQUA satellite-based AMSR-E (Advanced Microwave Scanning Radiometer- Earth Observing System) and the aircraft-based PSR (Polarimetric Scanning Radiometer). The SMEX02 design focused on the collection of near simultaneous brightness temperature observations from each of these instruments and in situ soil moisture measurements at field- and domain- scale. This methodology provided a basis for a quantitative analysis of the soil moisture remote sensing potential of each instrument using in situ comparisons and retrieved soil moisture estimates through the application of a radiative transfer model. To this end, the two sensors are compared with respect to their estimation of soil moisture.
    Keywords: Geophysics
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  • 34
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    Publication Date: 2018-06-06
    Description: Titan displays seasonal changes in the distribution of gas and hazes in its atmosphere, in the character of its methane clouds, and in its temperatures and winds. While Cassini has observed some of these cha rges in detail, some are observable from Earth, and the period of mos t rapid change may be just about to begin in the years after equinox,
    Keywords: Lunar and Planetary Science and Exploration
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  • 35
    Publication Date: 2018-06-06
    Description: Titan, after Venus, is the second example in the solar system of an atmosphere with a global cyclostrophic circulation, but in this case a circulation that has a strong seasonal modulation in the middle atmosphere. Direct measurement of Titan's winds, particularly observations tracking the Huygens probe at 10 deg S, indicate that the zonal winds are mostly in the sense of the satellite's rotation. They generally increase with altitude and become cyclostrophic near 35 km above the surface. An exception to this is a sharp minimum centered near 75 km, where the wind velocity decreases to nearly zero. Zonal winds derived from temperatures retrieved from Cassini orbiter measurements, using the thermal wind equation, indicate a strong winter circumpolar vortex, with maximum winds of 190 m/s at mid northern latitudes near 300 km. Above this level, the vortex decays. Curiously, the stratospheric zonal winds and temperatures in both hemispheres are symmetric about a pole that is offset from the surface pole by about 4 deg. The cause of this is not well understood, but it may reflect the response of a cyclostrophic circulation to the onset between the equator, where the distance to the rotation axis is greatest, and the seasonally varying subsolar latitude. The mean meridional circulation can be inferred from the temperature field and the meridional distribution of organic molecules and condensates and hazes. Both the warm temperatures near 400 km and the enhanced concentration of several organic molecules suggest subsidence in the north polar region during winter and early spring. Stratospheric condensates are localized at high northern latitudes, with a sharp cut-off near 50 deg N. Titan's winter polar vortex appears to share many of the same characteristics of isolating high and low-latitude air masses as do the winter polar vortices on Earth that envelop the ozone holes. Global mapping of temperatures, winds, and composition in the troposphere, by contrast, is incomplete. The few suitable discrete clouds that have been found for tracking indicate smaller velocities than aloft, consistent: with the Huygens measurements, Along the descent trajectory, the Huygens measurements indicate eastward zonal winds down to 7 km, where they shift westward, and then eastward again below 1 km dawn to the surface. The low-latitude dune fields seen in Cassini RADAR images have been interpreted as longitudinal dunes occurring in a mean eastward zonal wind. This is not like Earth, where the low-latitude winds are westward above the surface. Because the net zonal-mean time-averaged torque exerted by the surface on the atmosphere should vanish, there must be westward flow over part of the surface; the question is where and when. The meridional contrast in tropospheric temperatures deduced from radio occultations at low, mid, and high latitudes. is small, approximately 5 K at the tropopause and approximately 3 K at the surface. This implies efficient heat transport, probably by axisymmetric meridional circulations. The effect of the methane "hydrological" cycle on the atmospheric circulation is not well constrained by existing measurements, Understanding the mature of the surface-atmosphere coupling will be critical to elucidating the atmospheric transports of momentum, heat, and volatiles.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Titan from Cassini-Huygens
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  • 36
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    In:  Other Sources
    Publication Date: 2018-06-06
    Description: The Moon is our closest planetary neighbor and the only extraterrestrial body to which humans have traveled, yet many questions about its origin and early history remain unanswered. Four papers published in this issue by scientific teams of the Japanese SELENE (Kaguya) mission offer a new global view of the Moon that helps to elucidate how the Moon evolved to its present state. The Moon is lopsided: Its visible nearside (tidally locked to face the Earth) is covered with smooth, dark volcanic mare, whereas the farside mainly consists of more heavily cratered, bright highland material. The differences in crustal thickness and density, apparent surface age, composition, and volcanic activity between the two sides are variously ascribed to external causes (such as a giant impact) or to internal causes (such as core formation, mantle convection, and crustal differentiation). The key to resolving these questions will be better data.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Science; Volume 323; No. 5916; 885-887
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  • 37
    Publication Date: 2018-06-06
    Description: The combined use of altimetry, Earth-based Doppler and Earth-based range measurements in the lunar reconnaissance orbiter (LRO) mission (Chin et al. in Space Sci Rev 129:391-419, 2007) has been examined in a simulation study. It is found that in the initial phases of the mission orbit and altimeter geolocation accuracies should be better than 10m in the radial component and 60m overall. It is demonstrated that LRO's precise 1-way laser range measurement from Earth-based stations (Smith et al. in Proceedings of the 15th International Laser Ranging Workshop, Canberra, Australia, October 15-20, 2006) will be useful for gravity recovery. The advantages of multiple laser beams are demonstrated for altimeter calibration, orbit determination and gravity recovery in general planetary settings as well as for LRO.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Journal of Geodesy; Volume 83; No. 8; 709-721
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  • 38
    Publication Date: 2018-06-06
    Description: We use the global magnetohydrodynamic (MHD) code BATS-R-US to model multipoint observations of Flux Transfer Event (FTE) signatures. Simulations with high spatial and temporal resolution predict that cavities of weak magnetic field strength protruding into the magnetosphere trail FTEs. These predictions are consistent with recently reported multi-point Cluster observations of traveling magnetopause erosion regions (TMERs).
    Keywords: Geophysics
    Type: Geophysical Research Letters (ISSN 0094-8276); Volume 36
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  • 39
    Publication Date: 2018-06-06
    Description: We present an analytical model for the magnetic field perturbations associated with flux transfer events (FTEs) on the dayside magnetopause as a function of the shear between the magnetosheath and magnetospheric magnetic fields and the ratio of their strengths. We assume that the events are produced by component reconnection along subsolar reconnection lines with tilts that depend upon the orientation of the interplanetary magnetic field (IMF), and show that the amplitudes of the perturbations generated during southward IMF greatly exceed those during northward IMF As a result, even if the distributions of magnetic reconnection burst durations/event dimensions are identical during periods of northward and southward IMF orientation, events occurring for southward IMF orientations must predominate in surveys of dayside events. Two factors may restore the balance between events occurring for northward and southward IMF orientations on the flanks of the magnetosphere. Events generated on the dayside magnetopause during periods of southward IMF move poleward, while those generated during periods of northward IMF slip dawnward or duskward towards the flanks. Due to differing event and magnetospheric magnetic field orientations, events that produce weak signatures on the dayside magnetopause during intervals of northward IMF orientation may produce strong signatures on the flanks.
    Keywords: Geophysics
    Type: Annales Geophysicae; Volume 27; No. 2; 895-903
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  • 40
    Publication Date: 2018-08-10
    Description: Tracking of the Mars Global Surveyor spacecraft has been used to measure changes in the long-wavelength gravity field of Mars and to estimate the seasonal mass of carbon dioxide that is deposited in the polar regions each fall and winter and sublimed back into the atmosphere every spring and summer. Observations spanning 4 Mars years have been analyzed. A clear and well-defined seasonal signal, composed of annual and semiannual periods, is seen in the lowest odd degree 3 coefficient but with less confidence in the lowest even degree 2, which is expected to be smaller and is also much more difficult to observe. Direct estimation of the seasonal mass exchange employing a simple, seasonally varying model of the size and height of each cap provides values that indicate some systematic departures from the deposition predicted by a general circulation model. Estimates are also obtained for the precession and nutation of the pole of rotation of Mars, the degree 2 tidal Love number, k2, and the mass of Phobos, the larger of Mars' two natural satellites.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Journal of Geophysical Research; Volume 114
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  • 41
    facet.materialart.
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    In:  CASI
    Publication Date: 2018-06-28
    Description: This chapter provides a brief wrap-up of the task group report and focuses on the overall conclusions and recommendations for future work for the CAWAPI and VFE-2 facets beyond the task group. The overall conclusion is that the Technology Readiness Level (TRL) of CFD solvers has been improved in predicting the flow-physics of vortex-dominated flows during the work of the task group, by having flight and wind-tunnel data available for comparison. Moreover, like all good scientific studies, this task group has identified flight conditions on the F-16XL airplane or wind-tunnel test conditions for a specific leading-edge radius on the 65 delta-wing model where the TRL still needs to be increased.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 37-1 - 37-4; RTO-TR-AVT-113
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  • 42
    Publication Date: 2018-06-28
    Description: This chapter identifies the benefits that occurred to the AVT-113 task group members and the resulting progress made to two separate vortical flow proposals for task group status being combined into one. Both of these proposals dealt with multiple-vortices, and though they shared different focuses, the general topic, as well as the specific features of this flow, made it of great interest to each sub-task or facet member. The joint meetings increased our overall understanding of vortical flow and the synergistic benefits are summarized in terms of experimental and computational data, virtual laboratory usage, dissemination of results, and career development.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 36-1 - 36-4; RTO-TR-AVT-113
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  • 43
    Publication Date: 2018-06-28
    Description: Nine groups participating in the CAWAPI project have contributed steady and unsteady viscous simulations of a full-scale, semi-span model of the F-16XL aircraft. Three different categories of flight Reynolds/Mach number combinations were computed and compared with flight-test measurements for the purpose of code validation and improved understanding of the flight physics. Steady-state simulations are done with several turbulence models of different complexity with no topology information required and which overcome Boussinesq-assumption problems in vortical flows. Detached-eddy simulation (DES) and its successor delayed detached-eddy simulation (DDES) have been used to compute the time accurate flow development. Common structured and unstructured grids as well as individually-adapted unstructured grids were used. Although discrepancies are observed in the comparisons, overall reasonable agreement is demonstrated for surface pressure distribution, local skin friction and boundary velocity profiles at subsonic speeds. The physical modeling, be it steady or unsteady flow, and the grid resolution both contribute to the discrepancies observed in the comparisons with flight data, but at this time it cannot be determined how much each part contributes to the whole. Overall it can be said that the technology readiness of CFD-simulation technology for the study of vehicle performance has matured since 2001 such that it can be used today with a reasonable level of confidence for complex configurations.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 16-1 - 16-35; RTO-TR-AVT-113
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  • 44
    Publication Date: 2018-06-28
    Description: In support of the Cranked Arrow Wing Aerodynamic Project International (CAWAPI) with its goal of improving the Technology Readiness Level of flow solvers by comparing results with measured F-16XL-1 flight data, NASA Langley employed the TetrUSS unstructured grid solver, USM3D, to obtain solutions for all seven flight conditions of interest. A newly available solver version that incorporates a number of turbulence models, including the two-equation linear and non-linear k- , was used in this study. As a first test, a choice was made to utilize only a single grid resolution with the solver for the simulation of the different flight conditions. Comparisons are presented with three turbulence models in USM3D, flight data for surface pressure, boundary-layer profiles, and skin-friction distribution, as well as limited predictions from other solvers. A result of these comparisons is that the USM3D solver can be used in an engineering environment to predict vortex-flow physics on a complex configuration at flight Reynolds numbers with a two-equation linear k- turbulence model.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 15-1 - 15-35; RTO-TR-AVT-113
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  • 45
    Publication Date: 2018-06-28
    Description: A review is presented of the initial experimental results and analysis that formed the basis the Vortex Flow Experiment 2 (VFE-2). The focus of this work was to distinguish the basic effects of Reynolds number, Mach number, angle of attack, and leading edge bluntness on separation-induced leading-edge vortex flows that are common to slender wings. Primary analysis is focused on detailed static surface pressure distributions, and the results demonstrate significant effects regarding the onset and progression of leading-edge vortex separation.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 18-1 - 18-22; RTO-TR-AVT-113
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  • 46
    Publication Date: 2018-06-28
    Description: In this chapter numerical simulations of the flow around F-16XL are performed as a contribution to the Cranked Arrow Wing Aerodynamic Project International (CAWAPI) using the PAB3D CFD code. Two turbulence models are used in the calculations: a standard k-epsilon model, and the Shih-Zhu-Lumley (SZL) algebraic stress model. Seven flight conditions are simulated for the flow around the F-16XL where the free stream Mach number varies from 0.242 to 0.97. The range of angles of attack varies from 0 deg to 20 deg. Computational results, surface static pressure, boundary layer velocity profiles, and skin friction are presented and compared with flight data. Numerical results are generally in good agreement with flight data, considering that only one grid resolution is utilized for the different flight conditions simulated in this study. The Algebraic Stress Model (ASM) results are closer to the flight data than the k-epsilon model results. The ASM predicted a stronger primary vortex, however, the origin of the vortex and footprint is approximately the same as in the k-epsilon predictions.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 7-1 - 7-29; RTO-TR-AVT-113
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  • 47
    Publication Date: 2018-06-28
    Description: The objective of the Cranked-Arrow Wing Aerodynamics Project International (CAWAPI) was to allow a comprehensive validation of Computational Fluid Dynamics methods against the CAWAP flight database. A major part of this work involved the generation of high-quality computational grids. Prior to the grid generation an IGES file containing the air-tight geometry of the F-16XL aircraft was generated by a cooperation of some of the CAWAPI partners. Based on this geometry description both structured and unstructured grids have been generated. The baseline structured (multi-block) grid (and a family of derived grids) has been generated by the National Aerospace Laboratory (NLR). The baseline all-tetrahedral and hybrid unstructured grids were generated at the NASA Langley Research Center and the U.S. Air Force Academy, respectively. To provide more geometrical resolution, additional unstructured grids were generated at EADS-MAS, the UTSimCenter, and Boeing Phantom Works. All the grids generated within the framework of CAWAPI will be discussed.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 4-1 - 4-17; RTO-TR-AVT-113
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  • 48
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    In:  CASI
    Publication Date: 2018-06-28
    Description: The RTO Task Group AVT-113 "Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft" was established in April 2003. Two facets of the group, "Cranked Arrow Wing Aerodynamic Project International (CAWAPI)" and "Vortex Flow Experiment-2 (VFE-2)", worked closely together. However, because of the different requirements of each part, the CAWAPI facet concluded its work earlier (December 2006) than the VFE-2 facet (December 2007). In this first chapter of the Final Report of the Task Group an overview on its work is given, and the objectives for the Task Group are described.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 1-1 - 1-5; RTO-TR-AVT-113
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  • 49
    Publication Date: 2018-06-28
    Description: Flight surface flow data of various types for the F-16XL-1 aircraft, employed in the Cranked Arrow Wing Aerodynamics Project (CAWAP), are available.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; A2-1; RTO-TR-AVT-113
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  • 50
    Publication Date: 2018-06-28
    Description: The Virtual Laboratory (VL) was to be an integral part of the database service that NASA provided to the international community, and for a brief period the VL was fully operational in the CAWAPI facet of the AVT-113 task group. This chapter details how one can construct a VL and also some of the lessons learned along the way that required changes to be made. The VL was to support both the CAWAPI and VFE-2 facets but due to the lack of funding and sufficient Information Technology (IT) support people with the right skills, the VFE-2 facet only reached the advanced planning stage with little software in place. However, both efforts point out the value of a VL in a task group like AVT-113 and illustrate that there needs to be a budgeted item for the IT effort to bring the VL to full operational status in each application.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 2-1 - 2-10; RTO-TR-AVT-113
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  • 51
    Publication Date: 2018-06-28
    Description: In the present paper the main results of the new experiments from VFE-2 are summarized. These include some force and moment results, surface and off-body measurements, as well as steady and fluctuating quantities. Some critical remarks are added, and an outlook for future investigations is given.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 24-1 - 24-27; RTO-TR-AVT-113
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  • 52
    Publication Date: 2018-06-28
    Description: This paper provides a brief history of the F-16XL-1 aircraft, its role in the High Speed Research (HSR) program and how it was morphed into the Cranked Arrow Wing Aerodynamics Project (CAWAP). Various flight, wind-tunnel and Computational Fluid Dynamics (CFD) data sets were generated during the CAWAP. These unique and open flight datasets for surface pressures, boundary-layer profiles and skin-friction distributions, along with surface flow data, are described and sample data comparisons given. This is followed by a description of how the project became internationalized to be known as Cranked Arrow Wing Aerodynamics Project International (CAWAPI) and is concluded by an introduction to the results of a 5-year CFD predictive study of data.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; 3-1 - 3-32; RTO-TR-AVT-113
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  • 53
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    In:  CASI
    Publication Date: 2018-06-28
    Description: In this Appendix, sample data are provided in support of Chapter 18. Links and references are also provided.
    Keywords: Aerodynamics
    Type: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft; A3.1-1 - A3.1-4; RTO-TR-AVT-113
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  • 54
    Publication Date: 2018-06-28
    Description: A computational fluid dynamics (CFD) method has been employed to compute vortical flows around slender wing/body configurations. The emphasis of the paper is on the effectiveness of an adaptive grid procedure in "capturing" concentrated vortices generated at sharp edges or flow separation lines of lifting surfaces flying at high angles of attack. The method is based on a tetrahedral unstructured grid technology developed at the NASA Langley Research Center. Two steady-state, subsonic, inviscid and Navier-Stokes flow test cases are presented to demonstrate the applicability of the method for solving vortical flow problems. The first test case concerns vortex flow over a simple 65 delta wing with different values of leading-edge radius. Although the geometry is quite simple, it poses a challenging problem for computing vortices originating from blunt leading edges. The second case is that of a more complex fighter configuration. The superiority of the adapted solutions in capturing the vortex flow structure over the conventional unadapted results is demonstrated by comparisons with the wind-tunnel experimental data. The study shows that numerical prediction of vortical flows is highly sensitive to the local grid resolution and that the implementation of grid adaptation is essential when applying CFD methods to such complicated flow problems.
    Keywords: Aerodynamics
    Type: Vortex Breakdown Over Slender Delta Wings; 11-1 - 11-36; AC/323(AVT-080)TP/253
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  • 55
    Publication Date: 2018-06-28
    Description: An experimental investigation for the flow about a 65 deg. delta wing has been conducted in the NASA Langley National Transonic Facility (NTF). The tests were conducted at Reynolds numbers, based on the mean aerodynamic chord, ranging from 6 million to 120 million and at Mach numbers ranging from 0.4 to 0.9. The model incorporated four different leading-edge bluntness values. The data include detailed static surfacepressure distributions as well as normal-force and pitching-moment coefficients. The test program was designed to quantify the effects of Mach number, Reynolds number, and leading-edge bluntness on the onset and progression of leading-edge vortex separation.
    Keywords: Aerodynamics
    Type: Vortex Breakdown Over Slender Delta Wings; 4-1 - 4-20; AC/323(AVT-080)TP/253
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  • 56
    Publication Date: 2018-06-06
    Description: An analysis of twentieth century tide gauge records reveals that the solar semidiurnal tide S, has been decreasing in amplitude along the eastern coast of North America and at the mid-ocean site Bermuda. In relative terms the observed rates are unusually large, of order 10% per century. Periods of greatest change, however, are inconsistent among the stations, and roughly half the stations show increasing amplitude since the late 1990s. Excepting the Gulf of Maine, lunar tides are either static or slightly increasing in amplitude; a few stations show decreases. Large changes in solar, but not lunar, tides suggest causes related to variable radiational forcing, but the hypothesis is at present unproven. Citation: Ray, R. D. (2009), Secular changes in the solar semidiurnal tide of the western North Atlantic Ocean
    Keywords: Geophysics
    Type: Geophysical Research Letters; Volume 36; L19601
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  • 57
    Publication Date: 2018-06-06
    Description: Mars may possess a global sub-surface groundwater table as an integral part of its current hydrological system, However, the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the 'Mars Express (MEx) spacecraft has yet to make a definitive detection of such a body of liquid water. In this work, we quantify. the conditions that would allow a detection of a deep aquifer and demonstrate that the lack of radar detection doses not uniquely role out the presence of such a body. Specifically, if the overlying crustal material has a conductivity above approximately 10(exp -5) S/m (equivalent to a loss tangent of 0.008), a radar echo frown an aquifer could be sufficiently attenuated by the intetvening medium to prevent its detection by MARSIS. As such, the lack of direct detection by MARSIS -- a "null result" does not rule out the possibility of the water table's existence.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Geophysical Research Letters; Volume 36
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  • 58
    Publication Date: 2018-06-06
    Description: On 12 March 2008, the Cassini spacecraft made a close encounter with the Saturnian moon Enceladus, passing within 52 km of the moon. The spacecraft trajectory was intentionally-oriented in a southerly direction to create a close alignment with the intense water-dominated plumes emitted from the south polar region. During the passage, the Cassini Radio and Plasma Wave System (RPWS) detected two distinct radio signatures: 1) Impulses associated with small water-ice dust grain impacts and 2) an upper hybrid (UH) resonance emission that both intensified and displayed a sharp frequency decrease in the near-vicinity of the moon. The frequency decrease of the UH emission is associated with an unexpectedly sharp decrease in electron density from approximately 90 el/cubic cm to below 20 el/cubic cm that occurs on a time scale of a minute near the closest encounter with the moon. In this work, we consider a number of scenarios to explain this sharp electron dropout, but surmise that electron absorption by ice grains is the most likely process.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Geophysical Research Letters; Volume 36; L10203
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  • 59
    Publication Date: 2018-06-06
    Description: We use infrared images obtained by the Thermal Emission Imaging System (THEMIS) instrument on-board Mars Odyssey to retrieve the optical depth of dust and water ice aerosols over more than 3.5 martian years between February 2002 (MY 25, Ls=330 ) and December 2008 (MY 29, Ls=183). These data provide an important bridge between earlier TES observations and recent observations from Mars Express and Mars Reconnaissance Orbiter. An improvement to our earlier retrieval to include atmospheric temperature information from THEMIS Band 10 observations leads to much improved retrievals during the largest dust storms. The new retrievals show moderate dust storm activity during Mars Years 26 and 27, although details of the strength and timing of dust storms is different from year to year. A planet-encircling dust storm event was observed during Mars Year 28 near Southern Hemisphere Summer solstice. A belt of low-latitude water ice clouds was observed during the aphelion season during each year, Mars Years 26 through 29. The optical depth of water ice clouds is somewhat higher in the THEMIS retrievals at approximately 5:00 PM local time than in the TES retrievals at approximately 2:00 PM, suggestive of possible local time variation of clouds.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Icarus; Volume 202; Iss. 2; 444-452
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  • 60
    Publication Date: 2018-06-06
    Description: We have integrated the Fok radiation belt environment (RBE) model into the space weather modeling framework (SWMF). RBE is coupled to the global magnetohydrodynamics component (represented by the Block-Adaptive-Tree Solar-wind Roe-type Upwind Scheme, BATS-R-US, code) and the Ionosphere Electrodynamics component of the SWMF, following initial results using the Weimer empirical model for the ionospheric potential. The radiation belt (RB) model solves the convection-diffusion equation of the plasma in the energy range of 10 keV to a few MeV. In stand-alone mode RBE uses Tsyganenko's empirical models for the magnetic field, and Weimer's empirical model for the ionospheric potential. In the SWMF the BATS-R-US model provides the time dependent magnetic field by efficiently tracing the closed magnetic field-lines and passing the geometrical and field strength information to RBE at a regular cadence. The ionosphere electrodynamics component uses a two-dimensional vertical potential solver to provide new potential maps to the RBE model at regular intervals. We discuss the coupling algorithm and show some preliminary results with the coupled code. We run our newly coupled model for periods of steady solar wind conditions and compare our results to the RB model using an empirical magnetic field and potential model. We also simulate the RB for an active time period and find that there are substantial differences in the RB model results when changing either the magnetic field or the electric field, including the creation of an outer belt enhancement via rapid inward transport on the time scale of tens of minutes.
    Keywords: Geophysics
    Type: Journal of Atmospheric and Solar-Terrestrial Physics; Volume 71; Issue 16; 1653-1663
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  • 61
    Publication Date: 2018-06-06
    Description: Stratospheric ozone is expected to increase during the 21st century as the abundance of halogenated ozone-depleting substances decrease to 1960 values. However, climate change will likely alter this "recovery" of stratospheric ozone by changing stratospheric temperatures, circulation, and abundance of reactive chemical species. Here we quantity the contribution of different mechanisms to changes in upper stratospheric ozone from 1960 to 2100 in the Goddard Earth Observing System Chemistry-Climate Model (GEOS CCM), using multiple linear regression analysis applied to simulations using either Alb or A2 greenhouse gas (GHG) scenarios. In both these scenarios upper stratospheric ozone has a secular increase over the 21st century. For the simulation using the Alb GHG scenario, this increase is determined by the decrease in halogen amounts and the greenhouse gas induced cooling, with roughly equal contributions from each mechanism. There is a larger cooling in the simulation using the A2 GHG scenario, but also enhanced loss from higher NOy and HOx concentrations, which nearly offsets the increase due to cooler temperatures. The resulting ozone evolutions are similar in the A2 and Alb simulations. The response of ozone due to feedbacks from temperature and HOx changes, related to changing halogen concentrations, are also quantified using simulations with fixed halogen concentrations.
    Keywords: Geophysics
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  • 62
    Publication Date: 2018-06-06
    Description: The Laser Interferometer Space Antenna (LISA) mission. a space based gravitational wave detector. uses laser metrology to measure distance fluctuations between proof masses aboard three spacecraft. LISA is unique from a mission design perspective in that the three spacecraft and their associated operations form one distributed science instrument. unlike more conventional missions where an instrument is a component of an individual spacecraft. The design of the LISA spacecraft is also tightly coupled to the design and requirements of the scientific payload; for this reason it is often referred to as a "sciencecraft." Here we describe some of the unique features of the LISA spacecraft design that help create the quiet environment necessary for gravitational wave observations.
    Keywords: Spacecraft Design, Testing and Performance
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  • 63
    Publication Date: 2018-06-06
    Description: Tectonic patterns on Europa are influenced by tidal stress. An important well-organized component is associated with the orbital eccentricity, which produces a diurnally varying stress as Jupiter's apparent position in Europa's sky oscillates in longitude. Cycloidal lineaments seem to have formed as cracks propagated in this diurnally varying stress field. Maps of theoretical cycloid patterns capture many of the characteristics of the observed distribution on Europa. However, a few details of the observed cycloids distribution have not reproduced by previous models. Recently, it has been shown that Europa has a finite forced obliquity, so Jupiter's apparent positon in Europa's sky will also oscillate in latitude. We explore this new type of diurnal effect on cycloid formation. We find that stress from obliquity may be the key to explaining several characteristics of observed cycloids such as the shape of equator-crossing cycloids and the shift in the crack patterns in the Argadnel Regio region. All of those improvements of the fit between observaiton and theory seem to require Jupiter crossing Europa's equatorial plane 45 deg. to 180 deg after perijove passage. Suggestive of complex orbital dynamics that lock the direction of Europe's pericenter with the direction of the ascending node at the time these cracks were formed.
    Keywords: Lunar and Planetary Science and Exploration
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  • 64
    Publication Date: 2018-06-06
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
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  • 65
    Publication Date: 2018-06-06
    Description: This paper describes the AIRS Science Team Version 5 retrieval algorithm in terms of its three most significant improvements over the methodology used in the AIRS Science Team Version 4 retrieval algorithm. Improved physics in Version 5 allows for use of AIRS clear column radiances in the entire 4.3 micron CO2 absorption band in the retrieval of temperature profiles T(p) during both day and night. Tropospheric sounding 15 micron CO2 observations are now used primarily in the generation of clear column radiances .R(sub i) for all channels. This new approach allows for the generation of more accurate values of .R(sub i) and T(p) under most cloud conditions. Secondly, Version 5 contains a new methodology to provide accurate case-by-case error estimates for retrieved geophysical parameters and for channel-by-channel clear column radiances. Thresholds of these error estimates are used in a new approach for Quality Control. Finally, Version 5 also contains for the first time an approach to provide AIRS soundings in partially cloudy conditions that does not require use of any microwave data. This new AIRS Only sounding methodology, referred to as AIRS Version 5 AO, was developed as a backup to AIRS Version 5 should the AMSU-A instrument fail. Results are shown comparing the relative performance of the AIRS Version 4, Version 5, and Version 5 AO for the single day, January 25, 2003. The Goddard DISC is now generating and distributing products derived using the AIRS Science Team Version 5 retrieval algorithm. This paper also described the Quality Control flags contained in the DISC AIRS/AMSU retrieval products and their intended use for scientific research purposes.
    Keywords: Geophysics
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  • 66
    Publication Date: 2018-06-06
    Description: This paper presents a spherical harmonic analysis of the plasma velocity distribution function using high-angular, energy, and time resolution Cluster data obtained from the PEACE spectrometer instrument to demonstrate how this analysis models the particle distribution function and its moments and anisotropies. The results show that spherical harmonic analysis produced a robust physical representation model of the velocity distribution function, resolving the main features of the measured distributions. From the spherical harmonic analysis, a minimum set of nine spectral coefficients was obtained from which the moment (up to the heat flux), anisotropy, and asymmetry calculations of the velocity distribution function were obtained. The spherical harmonic method provides a potentially effective "compression" technique that can be easily carried out onboard a spacecraft to determine the moments and anisotropies of the particle velocity distribution function for any species. These calculations were implemented using three different approaches, namely, the standard traditional integration, the spherical harmonic (SPH) spectral coefficients integration, and the singular value decomposition (SVD) on the spherical harmonic methods. A comparison among the various methods shows that both SPH and SVD approaches provide remarkable agreement with the standard moment integration method.
    Keywords: Geophysics
    Type: Journal of Geophysical Research; Vol 114; A01105
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  • 67
    Publication Date: 2018-06-05
    Description: We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.
    Keywords: Geophysics
    Type: Geophysical Research Letters; Volume 36
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  • 68
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    Publication Date: 2018-06-11
    Description: No abstract available
    Keywords: Spacecraft Design, Testing and Performance
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  • 69
    Publication Date: 2019-07-27
    Description: Completed thermal-mechanical and mechanical load testing: a) 6 re-entry heating tests (3 with loading to 50% DLL), 3 hypersonic cruise tests with loading to 50% DLL and 4 high-temperature modal survey tests. b) 9 tests to 100% DLL. High-temperature modal survey results were inconclusive due to exceeding capability of some accelerometers. Overall good correlation between analysis and measured results for windward and leeward surface temperatures. Generally poor correlation between analysis and measured results for spindle area temperatures. Excellent test-to-test repeatability in strain and deflection data for 100% DLL testing. In-situ thermography images taken before and after thermal testing showed only minor changes in initial defects. Final detailed thermography tests scheduled for completion in Oct 09. In process of completing test documentation and test data analysis. Final reports complete by Dec 09. All analysis, test data, test plans, reports, photos, etc. will be made available to the technical community via the CMC Wiki.
    Keywords: Spacecraft Design, Testing and Performance
    Type: DFRC-1069 , 2009 Fundamental Aeronautics Program Annual Meeting; 29 Sep. 1 Oct. 2009; Atlanta, GA; United States
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  • 70
    Publication Date: 2019-07-19
    Description: The outermost layers of the Martian atmosphere are thought to be scientifically unique due to the large influences exerted by the highly dynamic lower atmosphere and the direct input of the solar wind from above. The nature of the solar wind interaction with the upper atmosphere is of particular interest because Mars lacks a global magnetic field, but is well shielded over some regions by strong crustal magnetic fields. Under such circumstances, the direct impact of solar wind plasma may have resulted in enhanced loss of volatiles over the ages including the components of water. The history of upper atmosphere and solar wind interaction measurements at Mars will be reviewed, recent results from the Mars Global Surveyor and Mars Express summarized, and prospects for new scientific advances enabled by the measurements that will be made by planned orbiter and penetrator missions. Special attention will be given to planetary magnetic field measurements, the measurement of ionospheric currents driven by the solar wind, and the role of space weather modeling and forecasting in the future of Mars exploration.
    Keywords: Lunar and Planetary Science and Exploration
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  • 71
    Publication Date: 2019-07-19
    Description: Field geologists routinely assign rocks to one of three basic petrogenetic categories (igneous, sedimentary or metamorphic) based on microtextural and mineralogical information acquired with a simple magnifying lens. Indeed, such observations often comprise the core of interpretations of geological processes and history. The Multispectral Microscopic Imager (MMI) uses multi-wavelength, light-emitting diodes (LEDs) and a substrate-removed InGaAs focal-plane array to create multispectral, microscale reflectance images of geological samples (FOV 32 X 40 mm). Each pixel (62.5 microns) of an image is comprised of 21 spectral bands that extend from 470 to 1750 nm, enabling the discrimination of a wide variety of rock-forming minerals, especially Fe-bearing phases. MMI images provide crucial context information for in situ robotic analyses using other onboard analytical instruments (e.g. XRD), or for the selection of return samples for analysis in terrestrial labs. To further assess the value of the MMI as a tool for lunar exploration, we used a field-portable, tripod-mounted version of the MMI to image a variety of Apollo samples housed at the Lunar Experiment Laboratory, NASA s Johnson Space Center. MMI images faithfully resolved the microtextural features of samples, while the application of ENVI-based spectral end member mapping methods revealed the distribution of Fe-bearing mineral phases (olivine, pyroxene and magnetite), along with plagioclase feldspars within samples. Samples included a broad range of lithologies and grain sizes. Our MMI-based petrogenetic interpretations compared favorably with thin section-based descriptions published in the Lunar Sample Compendium, revealing the value of MMI images for astronaut and rover-mediated lunar exploration.
    Keywords: Geophysics
    Type: JSC-CN-18454 , Lunar Science Forum; Jul 21, 2009 - Jul 23, 2009; Moffett Field, CA; United States
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  • 72
    Publication Date: 2019-07-19
    Description: Presolar grains were identified in meteorite residues 20 years ago based on their exotic isotopic compositions. Their study has provide new insights into stellar evolution and the first view of the original building blocks of the solar system. Organic matter in meteorites and IDPs is highly enriched in D/H and N-15/N-14 at micrometer scales, possibly due to presolar organic grains. These anomalies are ascribed to the partial preservation of presolar cold molecular cloud material. Identifying the carriers of these anomalies and elucidating their physical and chemical properties may give new views of interstellar chemistry and better understanding of the original components of the protosolar disk. However, identifying the carriers has been hampered by their small size and the inability to chemically isolate them. Thanks to immediate careful collection of Tagish Lake meteorite specimen, as well as major advances in nano-scale analytical techniques and advanced sample preparation, we were able to show that in the Tagish Lake meteorite, the principle carriers of these isotopic anomalies are sub-micrometer, hollow organic globules. The organic globules likely formed by photochemical processing of organic ices in a cold molecular cloud or the outermost regions of the protosolar disk. Organic globules with similar physical, chemical, and isotopic properties are also recently found from Bells CM2 carbonaceous chondrite, in IDPs and in the comet Wild-2 samples returned by Stardust. These results support the view that microscopic organic grains were widespread constituents of the protoplanetary disk. Their exotic isotopic compositions trace their origins to the outermost portions of the protosolar disk or a presolar cold molecular cloud.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-18214 , AGU 2009 Joint Assembly, Meeting of the Americas; May 24, 2009 - May 27, 2009; Toronto; Canada
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  • 73
    Publication Date: 2019-07-19
    Description: Minimizing mass and volume is critically important for space hardware. Microchannel technology can be used to decrease both of these parameters for heat exchangers. Working in concert with NASA, Pacific Northwest National Laboratories (PNNL) has developed a microchannel liquid/liquid heat exchanger that has resulted in significant mass and volume savings. The microchannel heat exchanger delivers these improvements without sacrificing thermal and pressure drop performance. A conventional heat exchanger has been tested and the performance of it recorded to compare it to the microchannel heat exchanger that PNNL has fabricated. The microchannel heat exchanger was designed to meet all of the requirements of the baseline heat exchanger, while reducing the heat exchanger mass and volume. The baseline heat exchanger was designed to have an transfer approximately 3.1 kW for a specific set of inlet conditions. The baseline heat exchanger mass was 2.7 kg while the microchannel mass was only 2.0 kg. More impressive, however, was the volumetric savings associated with the microchannel heat exchanger. The microchannel heat exchanger was an order of magnitude smaller than the baseline heat exchanger (2180cm3 vs. 311 cm3). This paper will describe the test apparatus designed to complete performance tests for both heat exchangers. Also described in this paper will be the performance specifications for the microchannel heat exchanger and how they compare to the baseline heat exchanger.
    Keywords: Spacecraft Design, Testing and Performance
    Type: International Conference on Environmental Systems; Jul 11, 2010 - Jul 15, 2010; Barcelona; Spain
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  • 74
    Publication Date: 2019-07-19
    Description: NASA's Constellation Program has been developed to successfully return humans to the Lunar surface prior to 2020. The Constellation Program includes several different project offices including Altair, which is the next generation Lunar Lander. The planned Altair missions are very different than the Lunar missions accomplished during the Apollo era. These differences have resulted in a significantly different thermal control system architecture. The Altair project has employed a rather unique development approach as compared with previous manned spacecraft programs. Altair started the design process by developing a single-string (no fault tolerance), minimum functionality design. This first design and analysis cycle resulted in the baseline design for the entire process. From this point of departure, Altair continued the development process by adding vehicle functionality for the purposes of minimizing the risk of Loss Of Crew (LOC) and Loss Of Mission (LOM). Through the subsequent design and analysis cycles, the project office compared the added mass associated with the reduction of LOC/LOM and selected the most mass efficient design solutions. The current paper will summarize the Altair mission profile, the operational phases, and the LOC/LOM decisions that were made during the various design cycles. The evolution of the thermal control system design through Lunar Design and Analysis Cycle 3 (LDAC-3) will also be described in this paper.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-CN-19167 , 40th International Conference on Environmental Systems; Jul 11, 2010 - Jul 15, 2010; Barcelona; Spain
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  • 75
    Publication Date: 2019-07-19
    Description: Recently proposed flight research at NASA Dryden Flight Research Center (DFRC) has prompted study into the aerodynamic effects of modifications made to the surfaces of laminar airfoils. The research is focused on the high-aspect ratio, laminar-flow type wings commonly found on UAVs and other aircraft with a high endurance requirement. A broad range of instrumentation possibilities, such as structural, pressure, and temperature sensing devices may require the alteration of the airfoil outer mold line as part of the installation process. This study attempts to characterize the effect of installing this additiona1 instrumentation on key airfoil performance factors, such as transition location, lift and drag curves, and stall point. In particular, the general case of an airfoil that is channeled in the spanwise direction is considered, and the impact on key performance characteristics is assessed. Particular attention is focused on exploring the limits of channel depth and low-Reynolds number on performance and stall characteristics. To quantify the effect of increased skin friction due to premature transition caused by protruding or recessed instrumentation, two simplified, conservative scenarios are used to consider two potential sources of diaturbance: A) that leading edge alterations would cause linearly expanding areas (triangles) of turbulent flow on both surfaces of the wing upstream of the natural transition point, and B) that a channel or bump on the upper surface would trip turbulent flow across the whole upper surface upstream of the natural transition point. A potentially more important consideration than the skin friction drag increment is the change in overall airfoil performance due to the installation of instrumentation along most of the wingspan. To quantify this effect, 2D CFD simulations of the flow over a representative mid-span airfoil section were conducted in order to assess the change in lift and drag curves for the airfoil in the presence of disturbed flow due to the installed instrumentation. A discussion as to the impact on high-altitude and low-speed operation of this and similar aircraft is provided.
    Keywords: Aerodynamics
    Type: DFRC-847A , 47th AIAA Aerospace Sciences Meeting and Exhibit; Jan 05, 2009; Orlando, FL; United States
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  • 76
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    Publication Date: 2019-07-19
    Description: As envisaged by the 2000 astrophysics decadal survey panel: The main goal of Terrestrial Planet Finder (TPF) is nothing less than to search for evidence of life on terrestrial planets around nearby stars . Here, we consider how an optical telescope paired with a free-flying occulter blocking light from the star can reach this goal directly, without knowledge of results from prior astrometric, doppler, or transit exoplanet observations. Using design reference missions and other simulations, we explore the potential of TPF-O to find planets in the habitable zone around their central stars, to spectrally characterize the atmospheres of detected planets, and to obtain rudimentary information about their orbits. We emphasize the importance of ozone absorption in the UV spectrum of a planet as a marker of photosynthesis by plants, algae, and cyanobacteria.
    Keywords: Lunar and Planetary Science and Exploration
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  • 77
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    Publication Date: 2019-07-19
    Description: The LISA Technology Package (LTP) is the payload of the European Space Agency's LISA Pathfinder mission. LISA Pathfinder was instigated to test, in a flight environment, the critical technologies required by LISA; namely, the inertial sensing subsystem and associated control laws and micro-Newton thrusters required to place a macroscopic test mass in pure free-fall. The UP is in the late stages of development -- all subsystems are currently either in the final stages of manufacture or in test. Available flight units are being integrated into the real-time testbeds for system verification tests. This poster will describe the UP and its subsystems, give the current status of the hardware and test campaign, and outline the future milestones leading to the UP delivery.
    Keywords: Spacecraft Design, Testing and Performance
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  • 78
    Publication Date: 2019-07-19
    Description: Oort Cloud comets, as well as TNOs Makemake (2045 FYg), Quaoar, and Pluto, are known to contain ethane. However, even though this molecule is found on several outer Solar System objects relatively little information is available about its amorphous and crystalline phases. In new experiments, we have prepared ethane ices at temperatures applicable to the outer Solar System, and have heated and ion-irradiated these ices to study phase changes and ethane's radiation chemistry using mid-IR spectroscopy (2.2 - 16.6 microns). Included in our work is the meta-stable phase that exists at 35 - 55 K. These results, including newly obtained optical constants, are relevant to ground-based observational campaigns, the New Horizons mission, and supporting laboratory work. An improved understanding of solid-phase ethane may contribute to future searches for this and other hydrocarbons in the outer Solar System.
    Keywords: Geophysics
    Type: 41st annual meeting of the Division for Planetary Sciences (DPS) of the American Astronomical Society; Oct 05, 2009 - Oct 09, 2009; Fajardo; Puerto Rico
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  • 79
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    Publication Date: 2019-07-19
    Description: NASA's Fermi Observatory was launched June 11, 2009; the Fermi Gamma Ray Burst Monitor (GBM) began normal operations on July 14, about a month after launch, when the trigger algorithms were enabled. In the first year of operations we recorded emission from four magnetar sources; of these, only one was an old magnetar: SGR 1806+20. The other three detections were: SGR J0501+4516, newly discovered with Swift and extensively monitored with both Swift and GBM, SGR J1550-5418, a source originally classified as an Anomalous X-ray Pulsar (AXP) and a very recently discovered new source, SGR 0418+5729. I report below on the current status of the analyses efforts of the GBM data.
    Keywords: Lunar and Planetary Science and Exploration
    Type: M09-0711 , Scientific Organizing Committee; Sep 14, 2009 - Sep 18, 2009; Venice; Italy
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  • 80
    Publication Date: 2019-07-19
    Description: The Lunar Surface System Habitat Demonstration Unit (HDU) will require the project team to integrate a variety of contributions from NASA centers and potential outside collaborators and poses a challenge in integrating these disparate efforts into a cohesive architecture. To accomplish the development of the HDU from conception in June 2009 to rollout for operations in July 2010, the HDU team is using several strategies to mitigate risks and bring the separate efforts together. First, a set of design standards is being developed to define the interfaces between the various systems of HDU and to the payloads, such as the Geology Lab, that those systems will support. Scheduled activities such as early fit-checks and the utilization of a Habitat avionics test bed prior to equipment installation into HDU. A coordinated effort to establish simplified Computer Aided Design standards and the utilization of a modeling and simulation systems will aid in design and integration concept development. Finally, decision processes on the shell development including the assembly sequence and the transportation have been fleshed out early on HDU to maximize the efficiency of both integration and field operations.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-19096 , Earth and Space 2010; Mar 14, 2010 - Mar 17, 2010; Honolulu, HI; United States
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  • 81
    Publication Date: 2019-07-13
    Description: One of the goals of In-Situ Resource Utilization (ISRU) on the moon is to produce oxygen from the lunar regolith which is present in the form of Ilmenite (FeTi03) and other compounds. A reliable and attainable method of extracting some of the oxygen from the lunar regolith is to use the hydrogen reduction process in a hot reactor to create water vapor which is then condensed and electrolyzed to obtain oxygen for use as a consumable. One challenge for a production system is to reliably acquire the regolith with an excavator hauler mobility platform and then introduce it into the reactor inlet tube which is raised from the surface and above the reactor itself. After the reaction, the hot regolith (-1000 C) must be expelled from the reactor for disposal by the excavator hauler mobility system. In addition, the reactor regolith inlet and outlet tubes must be sealed by valves during the reaction in order to allow collection of the water vapor by the chemical processing sub-system. These valves must be able to handle abrasive regolith passing through them as well as the heat conduction from the hot reactor. In 2008, NASA has designed and field tested a hydrogen reduction system called ROxygen in order to demonstrate the feasibility of extracting oxygen from lunar regolith. The field test was performed with volcanic ash known as Tephra on Mauna Kea volcano on the Big Island of Hawai'i. The tephra has similar properties to lunar regolith, so that it is regarded as a good simulant for the hydrogen reduction process. This paper will discuss the design, fabrication, operation, test results and lessons learned with the ROxygen regolith feed system as tested on Mauna Kea in November 2008.
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-2009-006 , 2nd Symposium On Space Resource Utilization at 47th AIAA Aerospace Sciences Meeting; Jan 05, 2009 - Jan 08, 2009; Orlando, FL; United States
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  • 82
    Publication Date: 2019-07-13
    Description: The magnetosphere contains a significant amount of ionospheric O+, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multifluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single-fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multifluid MHD model (with outflow) gives comparable results to the multispecies MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multispecies and multifluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H+ and O+, which is not possible when utilizing the other techniques considered
    Keywords: Geophysics
    Type: Journal of Geophysical Research (ISSN 0148-0227); 114
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  • 83
    Publication Date: 2019-07-13
    Description: Component and system sensitivities of some design parameters of ISRU system components are analyzed. The differences between terrestrial and lunar excavation are discussed, and a qualitative comparison of large and small excavators is started. The effect of excavator size on the size of the ISRU plant's regolith hoppers is presented. Optimum operating conditions of both hydrogen and carbothermal reduction reactors are explored using recently developed analytical models. Design parameters such as batch size, conversion fraction, and maximum particle size are considered for a hydrogen reduction reactor while batch size, conversion fraction, number of melt zones, and methane flow rate are considered for a carbothermal reduction reactor. For both reactor types the effect of reactor operation on system energy and regolith delivery requirements is presented.
    Keywords: Lunar and Planetary Science and Exploration
    Type: E-18256 , 47th AIAA Aerospace Sciences Meeting; Jan 05, 2009 - Jan 08, 2009; Orlando, FL; United States
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  • 84
    Publication Date: 2019-07-13
    Description: Surface mining of coal and subsequent reclamation represent the dominant land use change in the central Appalachian Plateau (CAP) region of the United States. Hydrologic impacts of surface mining have been studied at the plot scale, but effects at broader scales have not been explored adequately. Broad-scale classification of reclaimed sites is difficult because standing vegetation makes them nearly indistinguishable from alternate land uses. We used a land cover data set that accurately maps surface mines for a 187-km2 watershed within the CAP. These land cover data, as well as plot-level data from within the watershed, are used with HSPF (Hydrologic Simulation Program-Fortran) to estimate changes in flood response as a function of increased mining. Results show that the rate at which flood magnitude increases due to increased mining is linear, with greater rates observed for less frequent return intervals. These findings indicate that mine reclamation leaves the landscape in a condition more similar to urban areas rather than does simple deforestation, and call into question the effectiveness of reclamation in terms of returning mined areas to the hydrological state that existed before mining.
    Keywords: Geophysics
    Type: Water Resources Reserach; 45
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  • 85
    Publication Date: 2019-07-13
    Description: Unsteady 3-D RANS simulations have been performed on a highly loaded transonic turbine stage and results are compared to steady calculations as well as to experiment. A low Reynolds number k-epsilon turbulence model is employed to provide closure for the RANS system. A phase-lag boundary condition is used in the tangential direction. This allows the unsteady simulation to be performed by using only one blade from each of the two rows. The objective of this work is to study the effect of unsteadiness on rotor heat transfer and to glean any insight into unsteady flow physics. The role of the stator wake passing on the pressure distribution at the leading edge is also studied. The simulated heat transfer and pressure results agreed favorably with experiment. The time-averaged heat transfer predicted by the unsteady simulation is higher than the heat transfer predicted by the steady simulation everywhere except at the leading edge. The shock structure formed due to stator-rotor interaction was analyzed. Heat transfer and pressure at the hub and casing were also studied. Thermal segregation was observed that leads to the heat transfer patterns predicted by steady and unsteady simulations to be different.
    Keywords: Aerodynamics
    Type: E-17373 , 2009 Annual Meeting Fundamental Aeronautics Program Subsonic Fixed Wing Project; Sep 29, 2009 - Oct 01, 2009; Atlanta, GA; United States
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  • 86
    Publication Date: 2019-07-13
    Description: Integrated testing (such as Multi-Element Integrated Test (MEIT)) is critical to reducing risks and minimizing problems encountered during assembly, activation, and on-orbit operation of large, complex manned spacecraft. Provides the best implementation of "Test Like You Fly:. Planning for integrated testing needs to begin at the earliest stages of Program definition. Program leadership needs to fully understand and buy in to what integrated testing is and why it needs to be performed. As Program evolves and design and schedules mature, continually look for suitable opportunities to perform testing where enough components are together in one place at one time. The benefits to be gained are well worth the costs.
    Keywords: Spacecraft Design, Testing and Performance
    Type: KSC-2009-196R , Aerospace Testing Seminar; Oct 13, 2009 - Oct 15, 2009; Manhattan Beach, CA; United States
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  • 87
    Publication Date: 2019-07-13
    Description: One of the primary objectives of NASA's Vision for Space Exploration is the creation of a permanently manned lunar outpost. Facing the challenge of establishing a human presence on the moon will require new innovations and technologies that will be critical to expanding this exploration to Mars and beyond. However, accomplishing this task presents an unprecedented set of obstacles, one of the more significant of which is the development of new strategies for ground test and verification. Present concepts for the Lunar Surface System (LSS) architecture call for the construction of a series of independent yet tightly coupled modules and elements to be launched and assembled in incremental stages. Many of these will be fabricated at distributed locations and delivered shortly before launch, precluding any opportunity for testing in an actual integrated configuration. Furthermore, these components must operate flawlessly once delivered to the lunar surface since there is no possibility for returning a malfunctioning module to Earth for repair or modification. Although undergoing continual refinement, this paper will present the current state of the plans and models that have been devised for meeting the challenge of ground based testing for Constellation Program LSS as well as the rationale behind their selection.
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-2009-196 , Aerospace Testing Seminar; Oct 13, 2009 - Oct 15, 2009; Manhattan Beach, CA; United States
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  • 88
    Publication Date: 2019-07-13
    Description: A lightweight bulldozer blade prototype has been designed and built to be used as an excavation implement in conjunction with the NASA Chariot lunar mobility platform prototype. The combined system was then used in a variety of field tests in order to characterize structural loads, excavation performance and learn about the operational behavior of lunar excavation in geotechnical lunar simulants. The purpose of this effort was to evaluate the feasibility of lunar excavation for site preparation at a planned NASA lunar outpost. Once the feasibility has been determined then the technology will become available as a candidate element in the NASA Lunar Surface Systems Architecture. In addition to NASA experimental testing of the LANCE blade, NASA engineers completed analytical work on the expected draft forces using classical soil mechanics methods. The Colorado School of Mines (CSM) team utilized finite element analysis (FEA) to study the interaction between the cutting edge of the LANCE blade and the surface of soil. FEA was also used to examine various load cases and their effect on the lightweight structure of the LANCE blade. Overall it has been determined that a lunar bulldozer blade is a viable technology for lunar outpost site preparation, but further work is required to characterize the behavior in 1/6th G and actual lunar regolith in a vacuum lunar environment.
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-2009-226 , AIAA 2009 Space Conference and Exposition; Sep 14, 2009 - Sep 17, 2009; Pasadena, CA; United States
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  • 89
    Publication Date: 2019-07-13
    Description: Particle removal during lunar exploration activities is of prime importance for the success of robotic and human exploration of the moon. We report on our efforts to use electrostatic and dielectrophoretic forces to develop a dust removal technology that prevents the accumulation of dust on solar panels and removes dust adhering to those surfaces. Testing of several prototypes showed solar shield output above 90% of the initial potentials after dust clearing.
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-2009-032 , 11th International Conference on Electrostatics 2009; May 26, 2009 - May 29, 2009; Valencia; Spain
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  • 90
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-13
    Description: Lunar Water Resource Demonstration (LWRD) is part of RESOLVE (Regolith and Environment Science & Oxygen and Lunar Volatile Extraction). RESOLVE is an ISRU ground demonstration: (1) A rover to explore a permanently shadowed crater at the south or north pole of the Moon (2) Drill core samples down to 1 meter (3) Heat the core samples to 150C (4) Analyze gases and capture water and/or hydrogen evolved (5) Use hydrogen reduction to extract oxygen from regolith
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-2008-282 , 47th AIAA Aerospace Sciences Meeting; Jan 05, 2009 - Jan 08, 2009; Orlando, FL; United States
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  • 91
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-2009-133 , International Mars Society Convention; Jul 30, 2009 - Aug 02, 2009; College Park, MD; United States
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  • 92
    Publication Date: 2019-07-13
    Description: The Mars Science Laboratory (MSL) is the next step in NASA's Mars Exploration Program, currently scheduled for 2011. The spacecraft's descent into the Martian atmosphere will be slowed from Mach 2 to subsonic speeds via a large parachute system with final landing under propulsive control. A Disk-Band-Gap (DBG) parachute will be used on MSL similar to the designs that have been used on previous missions, however; the DBG parachute used by MSL will be larger (21.5 m) than in any of the previous missions due to the weight of the payload and landing site requirements. The MSL parachute will also deploy at higher Mach number (M 2) than previous parachutes, which can lead to instabilities in canopy performance. Both the increased size of the DBG above previous demonstrated configurations and deployment at higher Mach numbers add uncertainty to the deployment, structural integrity and performance of the parachute. In order to verify the performance of the DBG on MSL, experimental testing, including acquisition of Stereo Particle Imaging Velocimetry (PIV) measurements were required for validating CFD predictions of the parachute performance. A rigid model of the DBG parachute was tested in the 10x10 foot wind tunnel at GRC. Prior to the MSL tests, a PIV system had never been used in the 10x10 wind tunnel. In this paper we discuss some of the technical challenges overcome in implementing a Stereo PIV system with a 750x400 mm field-of-view in the 10x10 wind tunnel facility and results from the MSL hardshell canopy tests.
    Keywords: Lunar and Planetary Science and Exploration
    Type: AIAA Paper 2007- 0070 , E-17866 , AIAA 47th Aerospace Sciences Meeting; Jan 05, 2009 - Jan 08, 2009; Orlando, FL; United States
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  • 93
    Publication Date: 2019-07-13
    Description: A simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate monthly carbon fluxes in terrestrial ecosystems of Brazilian Amazon and Cerrado regions over the period 2000-2004. Net ecosystem production (NEP) flux for atmospheric CO2 in the region for these years was estimated. Consistently high carbon sink fluxes in terrestrial ecosystems on a yearly basis were found in the western portions of the states of Acre and Rondonia and the northern portions of the state of Par a. These areas were not significantly impacted by the 2002-2003 El Nino event in terms of net annual carbon gains. Areas of the region that show periodically high carbon source fluxes from terrestrial ecosystems to the atmosphere on yearly basis were found throughout the state of Maranhao and the southern portions of the state of Amazonas. As demonstrated though tower site comparisons, NEP modeled with monthly MODIS Enhanced Vegetation Index (EVI) inputs closely resembles the measured seasonal carbon fluxes at the LBA Tapajos tower site. Modeling results suggest that the capacity for use of MODIS Enhanced Vegetation Index (EVI) data to predict seasonal uptake rates of CO2 in Amazon forests and Cerrado woodlands is strong.
    Keywords: Geophysics
    Type: ARC-E-DAA-TN2279 , Biogeosciences; 6; 937-945
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  • 94
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-13
    Description: Multiple sonic boom wind tunnel models were tested in the NASA Ames Research Center 9-by 7-Foot Supersonic Wind Tunnel to reestablish related test techniques in this facility. The goal of the testing was to acquire higher fidelity sonic boom signatures with instrumentation that is significantly more sensitive than that used during previous wind tunnel entries and to compare old and new data from established models. Another objective was to perform tunnel-to-tunnel comparisons of data from a Gulfstream sonic boom model tested at the NASA Langley Research Center 4-foot by 4-foot Unitary Plan Wind Tunnel.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN569 , 111th Supersonic Tunnel Association International Meeting; May 04, 2009; Albuquerque, NM; United States
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  • 95
    Publication Date: 2019-07-13
    Description: Observations of the equatorial lunar sodium emission are examined to quantify the effect of precipitating ions on source rates for the Moon's exospheric volatile species. Using a model of exospheric sodium transport under lunar gravity forces, the measured emission intensity is normalized to a constant lunar phase angle to minimize the effect of different viewing geometries. Daily averages of the solar Lyman alpha flux and ion flux are used as the input variables for photon-stimulated desorption (PSD) and ion sputtering, respectively, while impact vaporization due to the micrometeoritic influx is assumed constant. Additionally, a proxy term proportional to both the Lyman alpha and to the ion flux is introduced to assess the importance of ion-enhanced diffusion and/or chemical sputtering. The combination of particle transport and constrained regression models demonstrates that, assuming sputtering yields that are typical of protons incident on lunar soils, the primary effect of ion impact on the surface of the Moon is not direct sputtering but rather an enhancement of the PSD efficiency. It is inferred that the ion-induced effects must double the PSD efficiency for flux typical of the solar wind at 1 AU. The enhancement in relative efficiency of PSD due to the bombardment of the lunar surface by the plasma sheet ions during passages through the Earth's magnetotail is shown to be approximately two times higher than when it is due to solar wind ions. This leads to the conclusion that the priming of the surface is more efficiently carried out by the energetic plasma sheet ions.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC.JA.4597.2011 , Icarus (ISSN 0019-1035); 205; 2; 364-374
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  • 96
    Publication Date: 2019-07-13
    Description: Space Technology 5 (ST5) is a constellation mission consisting of three microsatellites. It provides the first multipoint magnetic field measurements in low Earth orbit, which enables us to separate spatial and temporal variations. In this paper, we present a study of the temporal variability of field-aligned currents using the ST5 data. We examine the field-aligned current observations during and after a geomagnetic storm and compare the magnetic field profiles at the three spacecraft. The multipoint data demonstrate that mesoscale current structures, commonly embedded within large-scale current sheets, are very dynamic with highly variable current density and/or polarity in approx.10 min time scales. On the other hand, the data also show that the time scales for the currents to be relatively stable are approx.1 min for mesoscale currents and approx.10 min for large-scale currents. These temporal features are very likely associated with dynamic variations of their charge carriers (mainly electrons) as they respond to the variations of the parallel electric field in auroral acceleration region. The characteristic time scales for the temporal variability of mesoscale field-aligned currents are found to be consistent with those of auroral parallel electric field.
    Keywords: Geophysics
    Type: GSFC.JA.4531.2011 , Journal of Geophysical Research; 114
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  • 97
    Publication Date: 2019-07-12
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: LEGNEW-OLDGSFC-GSFC-LN-1225
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  • 98
    Publication Date: 2019-07-12
    Description: CanSat is an international student design-build-launch competition organized by the American Astronautical Society (AAS) and American Institute of Aeronautics and Astronautics (AIAA). The competition is also sponsored by the Naval Research Laboratory (NRL), the National Aeronautics and Space Administration (NASA), AGI, Orbital Sciences Corporation, Praxis Incorporated, and SolidWorks. Specifically, the 2009 Virginia Tech CanSat Team is funded by BAE Systems, Incorporated of Manassas, Virginia. The objective of the 2009 CanSat competition is to complete remote sensing missions by designing a small autonomous sounding rocket payload. The payload designed will follow and perform to a specific set of mission requirements for the 2009 competition. The competition encompasses a complete life-cycle of one year which includes all phases of design, integration, testing, reviews, and launch.
    Keywords: Spacecraft Design, Testing and Performance
    Type: KSC-2009-092
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  • 99
    Publication Date: 2019-07-12
    Description: The Surface Systems team is working to learn about lunar regolith and how we can use it as a source of air, water, and fuel for spacecrafts. However, excavation of this valuable regolith is difficult because the robot has to conform to many specifications (mass limit, efficiency level, etc.). NASA has therefore decided to include college students and companies in the search to create the best robot by making it into a competition.
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-2009-149
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  • 100
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-12
    Description: The Lunar Regolith Excavation Competition is a new competition that needs graphics, logos, rules, as well as an arena. Although this is the first year of the competition, the competition is modeled after an existing competition, the Centennial Lunar Excavator Challenge. This competition however is aimed at college students. This makes the challenge identifying key aspects of the original competition and modeling them to fit into an easier task, and creating exciting advertisement that helps encourage participation. By using a youth focus group, young insight, as well as guiding advice from experts in the field, hopefully an arena can be designed and built, rules can be molded and created to fit, and alluring graphics can be printed to bring about a successful first year of the Lunar Regolith Excavation Competition.
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-2009-155
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