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  • Lunar and Planetary Science and Exploration  (5,287)
  • Astrophysics  (2,594)
  • Cell & Developmental Biology
  • General Chemistry
  • Spacecraft Propulsion and Power
  • United States
  • 2015-2019  (3,634)
  • 2000-2004  (7,817)
  • 1945-1949  (1,249)
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  • 1
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    Unknown
    Temporal and spatial interactions between river bed roughness, geometry, bedload transport and flow hydraulics in mountain streams (2019)
    Inst. für Geograph. Wiss. der Freien Univ., Berlin
    In:  Herausgeberexemplar (FU Berlin) | ZB 20559:59
    Details
    Publication Date: 2021-03-29
    Description: The study explores the influence of bedload transport and flow hydraulics on the spatial and temporal dynamics of bed roughness and geometry in mountain streams. In order to investigate these complex interrelationships, each topic is treated separately. A new relative roughness coefficient, K3, is applied in the spatial and temporal roughness analyses. Detailed analyses of the highly variable natural fluid and sedimentary interactions are performed in the three mountain streams instead of using an estimated mean shear stress value to predict and describe river bed dynamics. Finally, the spatial and temporal interrelationships between roughness, geometry, flow dynamics and bedload transport are summarised in the new F.A.S.T. (Fluid And Sediment Transfer) model.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 910.02 ; Hydrodynamik, Strömungslehre {Hydrologie, Flüsse} ; Flow Dynamics ; Flow Hydraulics ; Bedload ; Bed Roughness ; Mountain Stream ; Germany ; United States
    Language: English
    Type: monograph_digi
    Format: 232
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  • 2
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    Die Stauanlagen der mittleren Vereinigten Staaten (2019)
    Reimer, Berlin
    In:  Herausgeberexemplar (FU Berlin) | 4 Z GEOGR 107:1
    Details
    Publication Date: 2021-03-29
    Description: Das Schwergewicht der wenigen geographischen Arbeiten über Stauanlagen lag bisher in der Aufdeckung allgemeiner, meist vom Zwecke der Anlagen losgelöster Zusammenhänge und Forderungen des Talsperrenbaus. Untersuchungen über die geographisch bedingte Zielsetzung und damit Verbreitung der Anlagen über den Raum und ihre Auswirkungen, vor allem wirtschaftsgeographischer Art, liegen dagegen nur ganz vereinzelt vor. Demgegenüber soll es das Ziel dieser Arbeit sein, diesen geographisch bedingten Zwecken und den unendlich mannigfaltigen Einwirkungen der Stauanlagen auf die Wirtschafts- und Kulturlandschaft nachzugehen und aus der Fülle der Verknüpfungen das für den jeweiligen Raum Entscheidende aufzudecken. Es sind also die Fragen der oben zitierten zweiten, bedeutenderen geographischen Fragestellung („die Untersuchung der geographischen Bedingtheit der Zielsetzungen der Talsperren und, nach deren Erreichen, ihres Einflusses auf die Landschaft“), auf die für den Raum der zentralen Landschaften der USA eine Antwort zu geben versucht werden soll.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 910 ; Oberflächenwasser {Hydrologie, USA} ; Geografie ; Stauanlagen ; United States ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 104
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  • 3
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    Journal of Geophysics - Zeitschrift für Geophysik 40 (2019)
    Springer, Berlin
    In:  SUB Göttingen | 8 Z NAT 2148:40
    Details
    Publication Date: 2021-03-29
    Description: Dieser Band enthält 134 Artikel zu Themengebieten der Seismologie, Erdmagnetismus und Gesteinsphysik veröffentlicht durch die Deutsche Geophysikalische Gesellschaft in dem Jahr 1974.
    Description: Inhaltsverzeichnis: Journal of Geophysics 40 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0010.pdf"〉Seegravimetrie〈/a〉〈br〉 (Fleischer, U.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0014.pdf"〉Statistical analysis of the pitch angle distribution of magnetospheric solar protons during geomagnetic activity〈/a〉〈br〉 (Scholer, M., Morfill, G., Hovestadt, D.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0016.pdf"〉Viscosity-depth-structure of different tectonic units and possible consequences for the upper part of converging plates〈/a〉〈br〉 (Meissner, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0017.pdf"〉Die Magnetisierung von Bohrkernen aus einem Serpentinit-Vorkommen bei Erbendorf (Oberpfalz) (Schult, A.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0018.pdf"〉Estimates of in situ thermal diffusivity of the Ore-Bearing Rocks in some drillholes in the Skellefte Field (N. Sweden) using the annual temperature wave〈/a〉〈br〉 (Parasnis, D. S.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0019.pdf"〉Geophysical exploration for groundwater in the Lusaka District, Republic of Zambia〈/a〉〈br〉 (Töpfer, K.D., Legg, C. A.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0021.pdf"〉Neuere Versuche zum Dipol-Induktionsverfahren〈/a〉〈br〉 (Leppin, M.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0022.pdf"〉A field evaluation of Caner's broad-band geomagnetic induction instrumentation〈/a〉〈br〉 (Dragert, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0025.pdf"〉Seismic noise at 2 Hz in Europe〈/a〉〈br〉 (Plešinger, A.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0026.pdf"〉Crustal structure under the Ionian Sea〈/a〉〈br〉 (Weigel, W.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0028.pdf"〉Heat-Flow Measurements in Swiss Lakes〈/a〉〈br〉 (Von Herzen, R. P.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0029.pdf"〉Makroseismische Abschätzungen von Herdparametern österreichischer Erdbeben aus den Jahren 1905 - 1973〈/a〉〈br〉 (Franke, A., Gutdeutsch, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0030.pdf"〉Long range propagation of seismic energy in the lower lithosphere〈/a〉〈br〉 (Kind, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0033.pdf"〉Palaeomagnetism of tertiary volcanic rocks from the Ethiopian southern plateau and the Danakil Block〈/a〉〈br〉 (Schult, A.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0034.pdf"〉Calculation of the shape and position of the last closed field line boundary and the coordinates of the magnetopause neutral points in a theoretical magnetospheric field model〈/a〉〈br〉 (Voigt, G.-H.))〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0037.pdf"〉Doppler shift of auroral backscatter signals〈/a〉〈br〉 (Czechowsky, P.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0038.pdf"〉Spherical harmonic analysis of the DS-field during magnetic storms〈/a〉〈br〉 (Schreiber, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0041.pdf"〉Note on determining hourly mean values〈/a〉〈br〉 (Larsen, J. C.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0042.pdf"〉Seismic observations in Germany of a 10 t explosion off Scotland〈/a〉〈br〉 (Bonjer, K.-P., Kaminski, W., Kind, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0044.pdf"〉A method to reduce the measuring time for spinner magnetometers〈/a〉〈br〉 (Hummervoll, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0045.pdf"〉Book Reviews〈/a〉〈br〉 (Mayer, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0046.pdf"〉Transverse plasma waves in the solar wind close to the proton gyrofrequency〈/a〉〈br〉 (Rehn, H. W.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0047.pdf"〉Die magnetische Anomalie der Ivreazone〈/a〉〈br〉 (Albert, G.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0052.pdf"〉Second meeting of the European Geophysical Society〈/a〉〈br〉〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0053.pdf"〉On a high-frequency method for the measurement of susceptibilities and hysteresis losses of rocks and minerals between nitrogen temperature and 700 °C〈/a〉〈br〉 (Markert, H., Trissl, K.-H., Zimmermann, G. J.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0054.pdf"〉Kinetics of oxidation processes in titanomagnetites〈/a〉〈br〉 (Kropáček, V.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0056.pdf"〉Ultra sound absorption measurements in rock samples at low temperatures〈/a〉〈br〉 (Herminghaus, Ch., Berckhemer, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0058.pdf"〉Recordings with the Askania borehole tiltmeter (vertical pendulum) in the frequency range of earth's free oscillations〈/a〉〈br〉 (Flach, D., Große-Brauckmann, W.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0060.pdf"〉Heat flow measurements in northern Italy and heat flow maps of Europe〈/a〉〈br〉 (Haenel, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0062.pdf"〉Die Bestimmung der Transmissivität von Grundwasserleitern aus dem Einschwingverhalten des Brunnen-Grundwasserleitersystems〈/a〉〈br〉 (Krauss, I.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0063.pdf"〉Symposium on "Geomagnetic Anomalies, Rock Magnetism and Petrography"〈/a〉〈br〉 (Hahn, A., Hall, D. H., Dunlop, D. J., Kobayashi, Kazuo, Nomura, Masafumi, Lidiak, E. G.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0090.pdf"〉The AEROS mission〈/a〉〈br〉 (Lämmerzahl, P., Bauer, S. J.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0091.pdf"〉The AEROS-EUV Spectrometer〈/a〉〈br〉 (Schmidtke, G., Schweizer, W., Knothe, M.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0092.pdf"〉The retarding potential analyzer on AEROS-B〈/a〉〈br〉 (Spenner, K., Dumbs, A.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0094.pdf"〉Impedance probe. The AEROS-B electron density experiment〈/a〉〈br〉 (Neske, E., Kist, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0095.pdf"〉The AEROS neutral and ion mass-spectrometer〈/a〉〈br〉 (Krankowsky, D., Lämmerzahl, P., Bonner, F., Wieder, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0096.pdf"〉The neural atmosphere temperature experiment〈/a〉〈br〉 (Spencer, N. W., Pelz, D. T., Niemann, H. B.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0097.pdf"〉Atmospheric drag analysis with the AEROS Satellite〈/a〉〈br〉 (Roemer, Max, Wulf-Mathies, Carsten)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0098.pdf"〉Electromagnetic reflections in salt deposits〈/a〉〈br〉 (Thierbach, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0100.pdf"〉The structure of the Ries crater from geoelectric depth soundings〈/a〉〈br〉 (Ernstson, K.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0102.pdf"〉Measurements of magnetic total field anomalies in the Hon Graben, Libya〈/a〉〈br〉 (Schult, A.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0103.pdf"〉Correction〈/a〉〈br〉〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0104.pdf"〉Book reviews〈/a〉〈br〉 (Theile, B.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0105.pdf"〉Interplanetary magnetic fields and the propagation of cosmic rays〈/a〉〈br〉 (Wibberenz, G.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0106.pdf"〉Intensity and energy spectrum of electrons accelerated in the earth's bow shock〈/a〉〈br〉 (Anderson, K. A.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0107.pdf"〉Evidence from particle precipitation of two-way-convection in auroral latitudes〈/a〉〈br〉 (Hultqvist, B.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0110.pdf"〉Investigation of electron dynamics in the magnetosphere with electron beams injected from sounding rockets〈/a〉〈br〉 (Winckler, J. R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0113.pdf"〉Cosmic ray electrons in the atmosphere〈/a〉〈br〉 (Fulks, G., Meyer, P.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0114.pdf"〉Cosmic rays underground and the interplanetary magnetic field〈/a〉〈br〉 (Regener, Victor H., Regener, Eric)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0115.pdf"〉Harmonic temperature waves in a horizontally layered medium〈/a〉〈br〉 (Mundry, E.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0118.pdf"〉No transform faults on the moon〈/a〉〈br〉 (Stegena, L., Bérczi, Sz.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0121.pdf"〉Dominating trends of the anomalies of the gravity and magnetic fields in NE France and SW Germany〈/a〉〈br〉 (Edel, J. B.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0040/LOG_0122.pdf"〉Book Reviews〈/a〉〈br〉 (Strobach, K., Petersen, Nikolai)〈/a〉〈/li〉 〈/body〉 〈/html〉
    Description: research
    Description: DGG, DFG, SUB Göttingen
    Keywords: 550 ; Aeronomy ; AEROS (satellite) ; Africa ; Alps ; Applied Geophysics ; Aurora ; Austria ; Bow Shock of Earth ; Canada ; Cosmic Rays ; Crustal Structure ; Earthquakes ; Europe ; France ; Free Oscillation of Earth ; Geoelectrics ; Geomagnetic Anomalies ; Geomagnetic Deep Sounding ; Geomagnetic Secular Variation ; Geomagnetic Time Variations ; Gravity Anomalies ; Gravity ; Geothermics ; Germany ; Great Britain ; Heat Flow ; Hydrology ; Interplanetary Magnetic Field ; Ionian Sea ; Ionosphere ; Italy ; Lunar Seismology ; Lunar Tectonism ; Macquarie-Inseln ; Magnetosphere ; Mantle of Earth ; Marine Geophysics ; Pacific Ocean ; Paleomagnetism ; Particle Acceleration ; Plasma Waves ; Radio Waves ; Ries Crater ; Rock Magnetism ; Rock Physics ; Salt Deposits ; Seismic Deep Sounding ; Seismic Noise ; Seismic Refraction Measurements ; Seismic Wave Absorption ; Seismology ; Solar EUV Radiation ; Solar Wind ; Switzerland ; Tectonophysics ; Tiltmeter ; United States ; USSR ; Viscosity of Earth ; FID-GEO-DE-7
    Language: German , English
    Type: anthology_digi
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  • 4
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    Die Entwicklung der Wirtschaftsstruktur einer traditionellen Sozialgruppe (2019)
    Reimer, Berlin
    In:  Herausgeberexemplar (FU Berlin) | QA = 4 Z GEOGR 107:27
    Details
    Publication Date: 2021-03-29
    Description: Die vorliegende Arbeit "Die Entwicklung der Wirtschaftsstruktur einer traditionellen Sozialgruppe – Das Beispiel der Old Order Amish in Ohio, Indiana und Pennsylvania, USA" erwuchs aus meiner langjährigen Beschäftigung mit dieser Sozialgruppe. […] Dabei wurde festgestellt, dass diese Sozialgruppe bisher wenig Beachtung in der geographischen Forschung fand und eine Entwicklung ihrer Wirtschaftsstruktur in der Literatur gar keine Erwähnung findet. Es erhob sich die Frage, ob eine Entwicklung der Wirtschaftsstruktur tatsächlich bisher nicht stattgefunden hat. Dies schien bei einer vergleichenden Betrachtung der US-amerikanischen Agrarwirtschaft und deren Entwicklung undenkbar. Aufgrund dieser Überlegung wurde die Theorie aufgestellt, dass eine Entwicklung der Wirtschaftsstruktur der Old Order Amish stattgefunden haben muss. Verschiedene Hypothesen wurden formuliert, gemäß derer eine Entwicklung verlaufen sein könnte. Sie wurden in den USA auf ihre Gültigkeit überprüft.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 910 ; Nordöstliche Mitte {Geographie} ; Midwest ; Old Order Amish ; United States ; Agrarwirtschaft ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 176
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  • 5
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    Giant Planet Effects on Terrestrial Planet Formation and System Architecture (2019)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Using an updated collision model, we conduct a suite of high-resolution N-body integrations to probe the relationship between giant planet mass and terrestrial planet formation and system architecture. We vary the mass of the planets that reside at Jupiter's and Saturn's orbit and examine the effects on the interior terrestrial system.We find that massive giant planets are more likely to eject material from the outer edge of the terrestrial disc and produce terrestrial planets that are on smaller, more circular orbits. We do not find a strong correlation between exterior giant planet mass and the number of Earth analogues (analogous in mass and semi-major axis) produced in the system. These results allow us to make predictions on the nature of terrestrial planets orbiting distant Sun-like star systems that harbour giant planet companions on long orbits - systems that will be a priority for NASA's upcoming Wide-Field Infrared Survey Telescope (WFIRST) mission.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN69989 , Monthly Notices of the Royal Astronomical Society (ISSN 0035-8711) (e-ISSN 1365-8711); 485; 1; 541–549
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    NASA TECHNICAL REPORTS
  • 6
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    Confirming Interstellar C60(+) Using the Hubble Space Telescope (2019)
    In:  Other Sources
    Details
    Publication Date: 2019-05-21
    Description: Recent advances in laboratory spectroscopy lead to the claim of ionized Buckminsterfullerene (C60(+)) as the carrier of two diffuse interstellar bands (DIBs) in the near-infrared. However, irrefutable identication of interstellar C60(+) requires a match between the wavelengths and the expected strengths of all absorption features detectable in the laboratory and in space. Here we present Hubble Space Telescope (HST) spectra of the region covering the C60(+) 9348, 9365, 9428, and 9577 absorption bands toward seven heavily reddened stars. We focus in particular on searching for the weaker laboratory C60(+) bands, the very presence of which has been a matter for recent debate. Using the novel STIS-scanning technique to obtain ultra-high signal-to-noise spectra without contamination from telluric absorption that aficted previous ground-based observations, we obtained reliable detections of the (weak) 9365, 9428 and (strong) 9577 C60(+) bands. The band wavelengths and strength ratios are sufciently similar to those determined in the latest laboratory experiments that we consider this the rst robust identication of the 9428 band, and a conclusive conrmation of interstellar C60(+).
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN68405 , Astrophysical Journal Letters (ISSN 2041-8205) (e-ISSN 2041-8213); 875; 2; L28
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Consequences of Tidal Dissipation in a Putative Venusian Ocean (2019)
    In:  CASI
    Details
    Publication Date: 2019-05-25
    Description: The solar tide in an ancient Venusian ocean is simulated using a dedicated numerical tidal model. Simulations with varying ocean depth and rotational periods ranging from minus 243 to 64 sidereal Earth days are used to calculate the tidal dissipation rates and associated tidal torque. The results show that the tidal dissipation could have varied by more than 5 orders of magnitude, from 0.001 to 780 gigawatts (GW), depending on rotational period and ocean depth. The associated tidal torque is about 2 orders of magnitude below the present day Venusian atmospheric torque, and could change the Venusian daylength by up to 72 days per million years depending on rotation rate. Consequently, an ocean tide on ancient Venus could have had significant effects on the rotational history of the planet. These calculations have implications for the rotational periods of similarly close-in exoplanetary worlds and the location of the inner edge of the liquid water habitable zone.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN68852 , The Astrophysical Journal Letters (ISSN 2041-8205) (e-ISSN 2041-8213); 876; 2; L22
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    Impulsively Reflected Ions: A Plausible Mechanism for Ion Acoustic Wave Growth in Collisionless Shocks (2019)
    In:  Other Sources
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    Publication Date: 2019-05-22
    Description: We present recent high time resolution observations from an oblique (43 deg) shock crossing from the Magnetospheric Multiscale mission. Short-duration bursts between 10 and 100 ms of ion acoustic waves are observed in this event alongside a persistent reflected ion population. High time resolution (150 ms) particle measurements show strongly varying ion distributions between successive measurements, implying that they are bursty and impulsive by nature. Such signatures are consistent with ion bursts that are impulsively reflected at various points within the shock. We find that, after instability analysis using a Fried-Conte dispersion solver, the insertion of dispersive ion bursts into an already stable ion distribution can lead to wave growth in the ion acoustic mode for short durations of time. We find that impulsively reflected ions are a plausible mechanism for ion acoustic wave growth in the terrestrial bow shock and, furthermore, suggest that wave growth can lead to a small but measurable momentum exchange between the solar wind ions and the reflected population.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN68433 , Journal of Geophysical Research: Space Physics (e-ISSN 2169-9402); 124; 3; 1855-1865
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  • 9
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    Correlation between SFR Surface Density and Thermal Pressure of Ionized Gas in Local Analogs of High-redshift Galaxies (2019)
    In:  Other Sources
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    Publication Date: 2019-06-29
    Description: We explore the relation between the star formation rate (SFR) surface density (integration of SFR) and the interstellar gas pressure for nearby compact starburst galaxies. The sample consists of 17 green peas and 19 Lyman break analogs (LBAs). Green peas are nearby analogs of Ly alpha emitters at high redshift and LBAs are nearby analogs of Lyman break galaxies at high redshift. We measure the sizes of green peas using Hubble Space Telescope Cosmic Origins Spectrograph near-UV images with a spatial resolution of approximately 0.05 arcsec. We estimate the gas thermal pressure in H II regions by P equals N (sub total)Tk (sub B) approximately or equal to 2n (sub e)Tk (sub B). The electron density is derived using the [S II] doublet at 6716,6731 Angstroms and the temperature is calculated from the [O III] lines. The correlation is characterized by the integration of SFR equals 2.40 times 10 (sup -3) times solar mass per year per square kiloparsec times ((P divided by k (sub B)) divided by (10 ( sup 4) per cubic centimeter times K)) times (sup 1.33). Green peas and LBAs have high integration of SFR up to 1.2 solar masses per year per square kiloparsec and high thermal pressure in the H II region up to P divided by k (sub B) approximating 10 (sup 7.2) K cubic centimeters. These values are at the highest end of the range seen in nearby starburst galaxies. The high gas pressure and the correlation are in agreement with those found instar-forming galaxies at redshift approximating 2.5. These extreme pressures are shown to be responsible for driving galactic winds in nearby starbursts. These outflows may be crucial in enabling Ly alpha and Lyman-continuum to escape.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN67881 , Astrophysical Journal (ISSN 2041-8205) (e-ISSN 2041-8213); 872; 2; 146
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    A Limited Habitable Zone for Complex Life (2019)
    In:  CASI
    Details
    Publication Date: 2019-06-29
    Description: The habitable zone (HZ) is commonly defined as the range of distances from a host star within which liquid water, a key requirement for life, may exist on a planet's surface. Substantially more CO2 than present in Earth's modern atmosphere is required to maintain clement temperatures for most of the HZ, with several bars required at the outer edge. However, most complex aerobic life on Earth is limited by CO2 concentrations of just fractions of a bar. At the same time, most exoplanets in the traditional HZ reside in proximity to M dwarfs, which are more numerous than Sun-like G dwarfs but are predicted to promote greater abundances of gases that can be toxic in the atmospheres of orbiting planets, such as carbon monoxide (CO). Here we show that the HZ for complex aerobic life is likely limited relative to that for microbial life. We use a 1D radiative-convective climate and photochemical models to circumscribe a Habitable Zone for Complex Life (HZCL) based on known toxicity limits for a range of organisms as a proof of concept. We find that for CO2 tolerances of 0.01, 0.1, and 1 bar, the HZCL is only 21%, 32%, and 50% as wide as the conventional HZ for a Sun-like star, and that CO concentrations may limit some complex life throughout the entire HZ of the coolest M dwarfs. These results cast new light on the likely distribution of complex life in the universe and have important ramifications for the search for exoplanet biosignatures and technosignatures.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN70116 , The Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 878; 1; 19
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    GRAIL-Identified Gravity Anomalies in Oceanus Procellarum: Insight into Subsurface Impact and Magmatic Structures on the Moon (2019)
    In:  Other Sources
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    Publication Date: 2019-06-29
    Description: Four, quasi-circular, positive Bouguer gravity anomalies (PBGAs) that are similar in diameter (~90-190 km) and gravitational amplitude (〉 140 mGal contrast) are identified within the central Oceanus Procellarum region of the Moon. These spatially associated PBGAs are located south of Aristarchus Plateau, north of Flamsteed crater, and two are within the Marius Hills volcanic complex (north and south). Each is characterized by distinct surface geologic features suggestive of ancient impact craters and/or volcanic/plutonic activity. Here, we combine geologic analyses with forward modeling of high-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) mission in order to constrain the subsurface structures that contribute to these four PBGAs. The GRAIL data presented here, at spherical harmonic degrees 6660, permit higher resolution analyses of these anomalies than previously reported, and reveal new information about subsurface structures. Specifically, we find that the amplitudes of the four PBGAs cannot be explained solely by mare-flooded craters, as suggested in previous work; an additional density contrast is required to explain the high-amplitude of the PBGAs. For Northern Flamsteed (190 km diameter), the additional density contrast may be provided by impact-related mantle uplift. If the local crust has a density ~2800 kg/cu.m, then ~7 km of uplift is required for this anomaly, although less uplift is required if the local crust has a lower mean density of ~2500 kg/cu.m. For the Northern and Southern Marius Hills anomalies, the additional density contrast is consistent with the presence of a crustal complex of vertical dikes that occupies up to ~50% of the regionally thin crust. The structure of Southern Aristarchus Plateau (90 km diameter), an anomaly with crater-related topographic structures, remains ambiguous. Based on the relatively small size of the anomaly, we do not favor mantle uplift; however, understanding mantle response in a region of especially thin crust needs to be better resolved. It is more likely that this anomaly is due to subsurface magmatic material given the abundance of volcanic material in the surrounding region. Overall, the four PBGAs analyzed here are important in understanding the impact and volcanic/plutonic history of the Moon, specifically in a region of thin crust and elevated temperatures characteristic of the Procellarum KREEP Terrane.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN69978 , Icarus (ISSN 0019-1035); 331; 192-208
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    Mutual Orbit Orientations of Transneptunian Binaries (2019)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: We present Keplerian orbit solutions for the mutual orbits of 17 transneptunian binary systems (TNBs). For ten of them, the orbit had not previously been known: 60458 2000 CM (sub 114), 119979 2002 WC (sub 19), 160091 2000 OL (sub 67), 160256 2002 PD (sub 149), 469514 2003 QA (sub 91), 469705 Kagara, 508788 2000 CQ (sub 114), 508869 2002 VT (sub 130), 1999 RT (sub 214), and 2002 XH (sub 91). Seven more are systems where the size, shape, and period of the orbit had been published, but new observations have now eliminated the sky plane mirror ambiguity in its orientation: 90482 Orcus, 120347 Salacia-Actaea, 1998 WW (sub 31), 1999 OJ (sub 4), 2000 QL (sub 251), 2001 XR (sub 254), and 2003 TJ (sub 58). The dynamical masses we obtain from TNB mutual orbits can be combined with estimates of the objects' sizes from thermal observations or stellar occultations to estimate their bulk densities. The Kagara system is currently undergoing mutual events in which one component casts its shadow upon the other and/or obstructs the view of the other. Such events provide valuable opportunities for further characterization of the system. Combining our new orbits with previously published orbits yields a sample of 35 binary orbits with known orientations that can provide important clues about the environment in which outer solar system planetesimals formed, as well as their subsequent evolutionary history. Among the relatively tight binaries, with semimajor axes less than about 5 percent of their Hill radii, prograde mutual orbits vastly outnumber retrograde orbits. This imbalance is not attributable to any known observational bias. We suggest that this distribution could be the signature of planetesimal formation through gravitational collapse of local density enhancements such as caused by the streaming instability. Wider binaries, with semimajor axes greater than 5 percent of their Hill radii, are somewhat more evenly distributed between prograde and retrograde orbits, but with mutual orbits that are aligned or anti-aligned with their heliocentric orbits. This pattern could perhaps result from Kozai-Lidov cycles coupled with tidal evolution eliminating high inclination wide binaries.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN68830 , Icarus (ISSN 0019-1035) (e-ISSN 1090-2643)
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    A New Model of the Crustal Magnetic Field of Mars Using MGS and MAVEN (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-02
    Description: While devoid of an active magnetic dynamo field today, Mars possesses a remanent magnetic field that may reach several thousand nanoteslas locally. The exact origin and the events that have shaped the crustal magnetization remain largely enigmatic. Three magnetic field data sets from two spacecraft collected over 13 cumulative years have sampled the Martian magnetic field over a range of altitudes from 90 up to 6,000 km: (a) Mars Global Surveyor (MGS) magnetometer (19972006), (b) MGS Electron Reflectometer (19992006), and (c) Mars Atmosphere and Volatile EvolutioN (MAVEN) magnetometer (2014 to today). In this paper we combine these complementary data sets for the first time to build a new model of the Martian internal magnetic field. This new model improves upon previous ones in several aspects: comprehensive data coverage, refined data selection scheme, modified modeling scheme, discrete-to-continuous transformation of the model, and increased model resolution. The new model has a spatial resolution of 160 km at the surface, corresponding to spherical harmonic degree 134. It shows small scales and well-defined features, which can now be associated with geological signatures.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN70068 , Journal of Geophysical Research: Planets
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    Emission-Line Metallicities from the Faint Infrared Grism Survey and VLT/MUSE (2019)
    In:  Other Sources
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    Publication Date: 2019-07-02
    Description: We derive direct-measurement gas-phase metallicities of 7.4 〈 12 + log(O/H) 〈 8.4 for 14 low-mass emission- line galaxies at 0.3 〈 z 〈 0.8 identied in the Faint Infrared Grism Survey. We use deep slitless G102 grism spectroscopy of the Hubble Ultra Deep Field, dispersing light from all objects in the eld at wavelengths between 0.85 and 1.15 m. We run an automatic search routine on these spectra to robustly identify 71 emission-line sources, using archival data from Very Large Telescope (VLT)/Multi-Unit Spectroscopic Explorer (MUSE) to measure additional lines and conrm redshifts. We identify 14 objects with 0.3 〈 z 〈 0.8 with measurable [O III] 4363 emission lines in matching VLT/MUSE spectra. For these galaxies, we derive direct electron-temperature gas-phase metallicities with a range of 7.4 〈 12 + log(O/H) 〈 8.4. With matching stellar masses in the range of 10(exp 7.9) Solar Mass 〈 M(sub *) 〈 10(exp 10.4) Solar Mass, we construct a massmetallicity (MZ) relation and nd that the relation is offset to lower metallicities compared to metallicities derived from alternative methods (e.g., R(sub 23), O3N2, N2O2) and continuum selected samples. Using star formation rates derived from the H emission line, we calculate our galaxies position on the Fundamental Metallicity Relation, where we also nd an offset toward lower metallicities. This demonstrates that this emission-line-selected sample probes objects of low stellar masses but even lower metallicities than many comparable surveys. We detect a trend suggesting galaxies with higher Specic Star Formation (SSFR) are more likely to have lower metallicity. This could be due to cold accretion of metal-poor gas that drives star formation, or could be because outows of metal-rich stellar winds and SNe ejecta are more common in galaxies with higher SSFR.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN68614 , Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 874; 2; 125
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    Nuclear Thermal Propulsion (NTP) In-Space Propulsion Demo Formulation (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-02
    Description: No abstract available
    Keywords: Spacecraft Propulsion and Power
    Type: MSFC-E-DAA-TN70022
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    Direct Te Metallicity Calibration of R23 in Strong Line Emitters (2019)
    In:  Other Sources
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    Publication Date: 2019-07-02
    Description: The gas metallicity of galaxies is often estimated using strong emission lines such as the optical lines of [O iii] and [O ii]. The most common measure is "R23," defined as ([O ii]3726, 3729 + [O iii]4959,5007)/H. Most calibrations for these strong-line metallicity indicators are for continuum selected galaxies. We report a new empirical calibration of R23 for extreme emission-line galaxies using a large sample of about 800 star-forming green pea galaxies with reliable Te -based gas-phase metallicity measurements. This sample is assembled from Sloan Digital Sky Survey (SDSS) Data Release 13 with the equivalent width of the line [O iii]5007 〉 300 or the equivalent width of the line H 〉 100 in the redshift range 0.011 〈 z 〈 0.411. For galaxies with strong emission lines and large ionization parameter (which manifests as log [O iii]4959,5007/[O ii]3726,3729 0.6), R23 monotonically increases with log(O/H) and the double-value degeneracy is broken. Our calibration provides metallicity estimates that are accurate to within ~0.14 dex in this regime. Many previous R23 calibrations are found to have bias and large scatter for extreme emission-line galaxies. We give formulae and plots to directly convert R23 and [O iii]4959,5007/[O ii]3726,3729 to log(O/H). Since green peas are best nearby analogs of high-redshift Ly emitting galaxies, the new calibration offers a good way to estimate the metallicities of both extreme emission-line galaxies and high-redshift Ly emitting galaxies. We also report on 15 galaxies with metallicities less than 1/12 solar, with the lowest metallicities being 12+log(O/H) = 7.25 and 7.26.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN67882 , Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 872; 2; 145
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    Electric Propulsion and the Gateway: Sustainable Exploration of Cis-Lunar Space (2019)
    In:  CASI
    Details
    Publication Date: 2019-05-23
    Description: NASA is committed to a sustainable return of humans to the Moon for long-term exploration and utilization. Gateway will enable this sustained cis-lunar presence and provide the capabilities necessary to develop and deploy critical infrastructure.
    Keywords: Spacecraft Propulsion and Power
    Type: GRC-E-DAA-TN67049
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    The Refractive Index of Amorphous and Crystalline Water Ice in the UV-vis (2019)
    In:  Other Sources
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    Publication Date: 2019-05-18
    Description: Amorphous solid water (ASW) is found on icy dust grains in the interstellar medium (ISM), as well as on comets and other icy objects in the outer solar system. The optical properties of ASW are thus relevant for many astrophysical environments, but in the ultravioletvisible (UVvis), its refractive index is not well constrained. Here, we introduce a new method based on UVvis broadband interferometry to measure the wavelength dependent refractive index n() of amorphous water ice from 10 to 130 K, i.e., for different porosities, in the wavelength range of 210757 nm. We also present n() for crystalline water ice at 150 K, which allows us to compare our new method with literature data. Based on this, a method to calculate n(, ) as a function of wavelength and porosity is reported. This new approach carries much potential and is generally applicable to pure and mixed ice, both amorphous and crystalline. The astronomical and physicalchemical relevance and future potential of this work are discussed.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN68160 , The Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 875; 2
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    High-Resolution, Lightweight, and Low-cost X-Ray Optics for the Lynx Observatory (2019)
    In:  CASI
    Details
    Publication Date: 2019-05-18
    Description: We describe an approach to build an x-ray mirror assembly that can meet Lynxs requirements of high-angular resolution, large effective area, light weight, short production schedule, and low-production cost. Adopting a modular hierarchy, the assembly is composed of 37,492 mirror segments, each of which measures 100 mm 100 mm 0.5 mm. These segments are integrated into 611 modules, which are individually tested and qualified to meet both science performance and spaceflight environment requirements before they in turn are integrated into 12 metashells. The 12 metashells are then integrated to form the mirror assembly. This approach combines the latest precision polishing technology and the monocrystalline silicon material to fabricate the thin and lightweight mirror segments. Because of the use of commercially available equipment and material and because of its highly modular and hierarchical building-up process, this approach is highly amenable to automation and mass production to maximize production throughput and to minimize production schedule and cost. As of fall 2018, the basic elements of this approach, including substrate fabrication, coating, alignment, and bonding, have been validated by the successful building and testing of single-pair mirror modules. In the next few years, the many steps of the approach will be refined and perfected by repeatedly building and testing mirror modules containing progressively more mirror segments to fully meet science performance, spaceflight environments, as well as programmatic requirements of the Lynx mission and other proposed missions, such as AXIS.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN68353 , Journal of Astronomical Telescopes, Instruments, and Systems; 5; 2; 021012
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    The Distribution, Composition, and Particle Properties of Mars Mesospheric Aerosols: an Analysis of CRISM Visible/near-IR Limb Spectra with Context from Near-Coincident MCS and MARCI Observations (2019)
    In:  Other Sources
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    Publication Date: 2019-05-18
    Description: The Compact Reconnaissance Imaging Spectral Mapper (CRISM) onboard the Mars Reconnaissance Orbiter (MRO) obtains pole-to-pole observations (i.e., full MRO orbits) of vertical profiles for visible/near-IR spectra (=0.44.0 m), which are ideally suited to identifying the composition and particle sizes of Mars ice and dust aerosols over 50100 km altitudes in the Mars mesosphere. Within the coverage limitations of the CRISM limb data set, a distinct compositional dichotomy is found in Mars mesospheric ice aerosols. CO2 ice clouds appear during the aphelion period of Mars orbit (Solar Longitudes, Ls0160) at low latitudes (20S10N) over specific longitude regions (Meridiani, Valles Marineris) and at typical altitudes of 5575 km. Apart from faint water ice hazes below 55 km, mesospheric H2O ice clouds are primarily restricted to the perihelion orbital range (Ls160 350) at northern and southern mid-to-low latitudes with less apparent longitudinal dependences. Mars mesospheric CO2 clouds are presented in CRISM spectra with a surprisingly large range of particle sizes (cross section weighted radii, Reff=0.3 to 2.2 m). The smaller particle sizes (Reff 1 m) appear concentrated near the spatial (latitude and altitude) boundaries of their global occurrences. CRISM spectra of mesospheric CO2 clouds also show evidence of iridescence, indicating very narrow particle size distributions (effective variance, Veff0.03) and so very abrupt CO2 cloud nucleation. Furthermore, these clouds are sometimes accompanied by altitude coincident peaks in 1.27 m O2 dayglow, which indicates very dry, cold regions of formation. Mesospheric water ice clouds generally exhibit small particle sizes (Reff=0.10.3 m), although larger particle sizes (Reff=0.40.7 m) appear infrequently. On average, water ice cloud particle sizes decrease with altitude over 5080 km in the perihelion mesosphere. Water ice mass appears similar in clouds over a large range of observed cloud particle sizes, with particle number densities increasing to 10 cm3 for Reff=0.2 m. Near coincident Mars Climate Sounder (MCS) temperature and aerosol profile measurements for a subset of CRISM mesospheric aerosol measurements indicate near saturation (H2O and CO2) conditions for ice clouds and distinct mesospheric temperature increases associated with mesospheric dust loading. Dayside (3 pm) mesospheric CO2 clouds with larger particle sizes (Reff 0.5 m) scatter surface infrared emission in MCS limb infrared radiances, as well as solar irradiance in the MCS solar band channel. Scattering of surface infrared emission is most strikingly presented in nighttime (3 am) MCS observations at 5560 km altitudes, indicating extensive mesospheric nighttime CO2 clouds with considerably larger particle sizes (Reff7 m). Mesospheric CO2 ice clouds present cirrus-like waveforms over extensive latitude and longitude regions (1010), as revealed in coincident Mars Color Imager (MARCI) nadir imaging. Solar tides, gravity waves, and the large orbital variation of the extended thermal structure of the Mars atmosphere influence all of these behaviors. Mesospheric dust aerosols appear infrequently over the non-global (planet encircling) dust storm era of the CRISM limb data set (20092016), and exhibit smaller particle sizes (Reff=0.20.7 m) relative to dust in the lower atmosphere. One isolated case of an aphelion (Ls=96) mesospheric dust layer with large dust particle sizes (Reff 2 m) over Syria Planum may reflect high altitude, non-local transport of dust over elevated regions.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN68079 , Icarus (ISSN 0019-1035); 328; 246-273
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    Co-orbital Asteroids as the Source of Venus's Zodiacal Dust Ring (2019)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Photometry from the Helios and STEREO spacecraft revealed regions of enhanced sky surface-brightness suggesting a narrow circumsolar ring of dust associated with Venus's orbit. We model this phenomenon by integrating the orbits of 10,000,000+ dust particles subject to gravitational and non-gravitational forces, considering several different kinds of plausible dust sources. We find that only particles from a hypothetical population of Venus co-orbital asteroids can produce enough signal in a narrow ring to match the observations. Previous works had suggested such objects would be dynamically unstable. However, we re-examined the stability of asteroids in 1:1 resonance with Venus and found that ~8% should survive for the age of the solar system, enough to supply the observed ring.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN67865 , The Astrophysical Journal Letters,; 2; 873; L16
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    A 3 Gyr White Dwarf with Warm Dust Discovered via the Backyard Worlds: Planet 9 Citizen Science Project (2019)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Infrared excesses due to dusty disks have been observed orbiting white dwarfs with effective temperatures between 7200 and 25,000 K, suggesting that the rate of tidal disruption of minor bodies massive enough to create a coherent disk declines sharply beyond 1 Gyr after white dwarf formation. We report the discovery that the candidate white dwarf LSPM J0207+3331, via the Backyard Worlds: Planet 9 citizen science project and Keck Observatory follow-up spectroscopy, is hydrogen dominated with a luminous compact disk (L IR/L star = 14%) and an effective temperature nearly 1000 K cooler than any known white dwarf with an infrared excess. The discovery of this object places the latest time for large-scale tidal disruption events to occur at ~3 Gyr past the formation of the host white dwarf, making new demands of dynamical models for planetesimal perturbation and disruption around post-main-sequence planetary systems. Curiously, the mid-infrared photometry of the disk cannot be fully explained by a geometrically thin, optically thick dust disk as seen for other dusty white dwarfs, but requires a second ring of dust near the white dwarf's Roche radius. In the process of confirming this discovery, we found that careful measurements of WISE source positions can reveal when infrared excesses for white dwarfs are co-moving with their hosts, helping distinguish them from confusion noise.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN67863 , The Astrophysical Journal Letters; 2; 872; L25
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    Expected Occurrence Rates and Types of Planets Possible in the Alpha Centauri AB System (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-31
    Description: Alpha Centauri AB system contains the closest Sun-like stars to the Sun, by a large margin (factor of 2.4). Thus, they are important targets for the search of Earth-like planets. A critical question is whether such planets can exist in the system, and what their expected occurrence rate is. This paper surveys the current knowledge of occurrence rates, limits from nondetections, constraints from observations, and dynamical stability simulations, in order to answer this question.
    Keywords: Astrophysics
    Type: ARC-E-DAA-TN69636 , AbSciCon 2019; Jun 24, 2019 - Jun 28, 2019; Bellevue, WA; United States
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    TESS Data Release Notes: Sector 9, DR11 (2019)
    In:  CASI
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    Publication Date: 2019-06-26
    Description: This release note discusses the science data products produced by the Science Processing Operations Center at Ames Research Center from Sector 9 observations made with the TESS spacecraft and cameras as a means to document instrument performance and data characteristics.
    Keywords: Astrophysics
    Type: ARC-E-DAA-TN69031
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    TESS Data Release Notes: Sector 10, DR14 (2019)
    In:  CASI
    Details
    Publication Date: 2019-06-26
    Description: This release note discusses the science data products produced by the Science Processing Operations Center at Ames Research Center from Sector 10 observations made with the TESS spacecraft and cameras as a means to document instrument performance and data characteristics.
    Keywords: Astrophysics
    Type: NASA/TM-2019-220220 , ARC-E-DAA-TN69634
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    Wrinkle Ridges on Mercury and the Moon Within and Outside of Mascons (2019)
    In:  Other Sources
    Details
    Publication Date: 2019-06-26
    Description: Found on all terrestrial planets, wrinkle ridges are anticlines formed by thrust faulting and folding resulting from crustal shortening. The MErcury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft's orbital phase returned high resolution images and topographic data of the previously unimaged northern high latitudes of Mercury where there are large expanses of smooth plains deformed by wrinkle ridges. Concurrently, the Lunar Reconnaissance Orbiter (LRO) is obtaining high resolution images and topographic data covering lunar mare wrinkle ridges. These data allow quantitative comparison of the scale of wrinkle ridges in smooth plains volcanic units on Mercury with mare wrinkle ridges. We evaluate the topographic relief of 300 wrinkle ridges within and outside of mascon basins on the Moon and Mercury. Measured wrinkle ridges range from ~112 to 776 m in relief with a mean of ~350 m (median = ~340 m, n = 150) on Mercury and from ~47 to 678 m in relief with a mean of ~198 m (median = ~168 m, n = 150) on the Moon. Wrinkle ridges on Mercury thus are approximately twice as large in mean relief compared to their counterparts on the Moon. The larger scale of Mercury's wrinkle ridges suggests that their formation can be attributed, in part, to global contraction. As global contraction on the Moon is estimated to be an order of magnitude smaller than on Mercury, the smaller scale of lunar wrinkle ridges suggests they most likely form primarily by load induced subsidence of the mare basalt. Wrinkle ridges located in lunar mascon basins and in the Caloris mascon on Mercury are not statistically significantly different in relief than ridges in non-mascon regions, suggesting comparable levels of contractional strain. The fact that mascon basins do not host wrinkle ridges with greater structural relief relative to non-mascon units may indicate the critical role lithospheric thickness plays in controlling subsidence and contraction of thick volcanic sequences on the Moon and Mercury.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN70101 , Icarus (e-ISSN 0019-1035); 331; 226-237
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    Mars Phoenix EDL Trajectory and Atmosphere Reconstruction Using NewSTEP (2019)
    In:  CASI
    Details
    Publication Date: 2019-06-20
    Description: This document describes the trajectory and atmosphere reconstruction of the Mars Phoenix Entry, Descent, and Landing using the New Statistical Trajectory Estimation Program. The approach utilizes a Kalman filter to blend inertial measurement unit data with initial conditions and radar altimetry to obtain the inertial trajectory of the entry vehicle. The nominal aerodynamic database is then used in combination with the sensed accelerations to obtain estimates of the atmosphere-relative state. The reconstructed atmosphere pro le is then blended with pre-flight models to construct an estimate of the as-flown atmosphere.
    Keywords: Lunar and Planetary Science and Exploration
    Type: NASA/TM–2019–220282 , L-21028 , NF1676L-33202
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    Astro2020 Science White Paper: Prospects for Pulsar Studies at MeV Energies (2019)
    In:  CASI
    Details
    Publication Date: 2019-06-20
    Description: Enabled by the Fermi Large Area Telescope, we now know young and recycled pulsars fill the gamma-ray sky, and we are beginning to understand their emission mechanism and their distribution throughout the Galaxy. However, key questions remain: Is there a large population of pulsars near the Galactic center? Why do the most energetic pulsars shine so brightly in MeV gamma rays but not always at GeV energies? What is the source and nature of the pair plasma in pulsar magnetospheres, and what role does the polar cap accelerator play? Addressing these questions calls for a sensitive, wide-field MeV telescope, which can detect the population of MeV-peaked pulsars hinted at by Fermi and hard X-ray telescopes and characterize their spectral shape and polarization.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN69835
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    A Long-Term Vision for Space-Based Interferometry (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-03
    Description: The processes leading to the formation of planets; the extreme physics occurring near the event horizon of black holes; detailed studies of exoplanets through spectral-spatial mapping: new and unique insights into the physical processes involved across nearly the whole gamut of astrophysics await discovery at small angular scales. The fine spatial resolution needed to explore these processes, however, lies beyond the capabilities of current astronomical facilities and nearly all proposed future facilities. Interferometers can crack this angular resolution problem, and space-based interferometry missions promise to explore entirely new regions of scientific phase space, providing unique new insights into the physical processes lurking at small angular scales.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN70915
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    Lifetimes and Occurrence Rates of Dark Vortices on Neptune from 25 Years of Hubble Space Telescope Images (2019)
    In:  Other Sources
    Details
    Publication Date: 2019-06-13
    Description: We scoured the full set of blue-wavelength Hubble Space Telescope images of Neptune, finding one additional dark spot in new Hubble data beyond those discovered in 1989, 1994, 1996, and 2015. We report the complete disappearance of the SDS-2015 dark spot, using new Hubble data taken on 2018 September 910, as part of the Outer Planet Atmospheres Legacy (OPAL) program. Overall, dark spots in the full Hubble data set have lifetimes of at least one to two years, and no more than six years. We modeled a set of dark spots randomly distributed in time over the latitude range on Neptune that is visible from Earth, finding that the cadence of archival Hubble images would have detected about 70% of these spots if their lifetimes are only one year, or about 85%95% of simulated spots with lifetimes of two or more years. Based on the Hubble data set, we conclude that dark spots have average occurrence rates of one dark spot every four to six years. Many numerical models to date have simulated much shorter vortex lifetimes, so our findings provide constraints that may lead to improved understanding of Neptunes wind field, stratification, and humidity.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN68800 , Astronomical Journal (ISSN 0004-6256) (e-ISSN 1538-3881); 157; 4; 152; April 2019
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    Cross-Program Design Specification for Natural Environments (DSNE) (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-25
    Description: This document is derived from the former National Aeronautics and Space Administration (NASA) Constellation Program (CxP) document CxP 70023, titled The Design Specification for Natural Environments (DSNE), Revision C. The original document has been modified to represent updated Design Reference Missions (DRMs) for the NASA Exploration Systems Development (ESD) Programs.
    Keywords: Lunar and Planetary Science and Exploration
    Type: SLS-SPEC-159 Revision F , M19-7505
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    Picture this SELFI: Submillimeter Enceladus Life Fundamentals Instrument (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: The Submillimeter Enceladus Life Fundamentals Instrument (SELFI) is a passive remote sensing submillimeter heterodyne spectrometer being developed at NASA GSFC under NASA's Maturation of Instruments for Solar System Exploration (MatISSE) program. SELFI will advance submillimeter receiver technology by 1) investigating the chemical and isotopic compositions and corresponding densities of Enceladus' plume material, their vertical thermal structures, and the transport mechanisms within the plumes, and 2) characterizing the source regions from which the plumes emerge. The Enceladus plumes are important in the context of life and habitability of its subsurface ocean environment. SELFI remote sensing measurements will 1) measure the spatial and temporal variabilities in the plume chemical compositions, 2) provide insight in to Enceladus' subsurface ocean environment by monitoring H2O, HDO, d18O, and d17O, 3) constrain the oxidation state of the subsurface ocean using H2O2 and O3, and 4) utilize the SO2 and H2S spectral signatures to constrain the impact arising from both the sea-floor volcanoes and pre-biotic molecules. Moreover, the detection of the remaining molecular species (14 in total) is vital to improving the current state of knowledge of Enceladus' subsurface ocean habitability this also permits us to explore the chemical alteration processes arising from primordial volatiles that have been observed in comets. Lastly, SELFI's continuum observations enable the correlation between observed variations in plume activity with surface temperatures.SELFI is currently being developed under a technology maturation program that will advance the RF-to-digital electronics of a submillimeter-wave heterodyne spectrometer to simultaneously observe fourteen molecular species with resonances between 530 GHz and 600 GHz. SELFI will have fine radiometric resolution, high spectral resolution (resolving power R 〉 106), multiple continuum channels and a high dynamical range, necessary to map Enceladus across its 30 K to 250 K temperature range. Under the MatISSE program, SELFI will advance from TRL 4 to 6 four key technologies of the RF-to-digital subsystem, which are: 1) the RF low noise amplifier design; 2) the single-sideband (SSB) mixer and local oscillator; 3) the IF assembly down-converter that maps the fourteen species to 2 x 500 MHz bandwidth; and 4) the digital spectrometer electronics.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN64627 , National Radio Science Meeting (NRSM); Jan 09, 2019 - Jan 12, 2019; Boulder, CO; United States
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    The Mars Global Dust Storm of 2018 (2019)
    In:  CASI
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    Publication Date: 2019-07-17
    Description: Mars is a dusty planet. Wind often lifts dust from the surface into the air forming clouds of dust at different locations across Mars. These dust storms typically last up to a couple days and grow to a few hundred km in size. However, once in a long while when conditions are just right, localized dust storms can interact in a way that optically thick suspended dust covers nearly the entire planet remaining aloft for weeks to months. These global-scale dust storms are the most dramatic of all weather phenomena on Mars, greatly altering the thermal structure and dynamics of the Martian atmosphere and significantly changing the global distribution of surface dust. Such a global-scale dust storm occurred during the summer of 2018, the first such event since 2007. The global dust storm was observed by an international fleet of spacecraft in Mars orbit and on the surface of Mars providing an unprecedented view of the initiation, growth, and decay of the storm as well as the physical properties of the dust during the storm's evolution. The 2018 global-scale dust storm was observed to grow from several localized dust-lifting centers with wind-blown dust suspended in the atmosphere encircling Mars after about two weeks of activity. Dust column optical depths recorded by the Opportunity and Curiosity rovers on the surface were the highest ever recorded on Mars. Peak global intensity of the dust storm was reached in early July 2018. Over the next couple months, the dust settled out and the atmosphere returned to its climatological average. Only a small number of global-scale dust storms have been observed on Mars, and so detailed analysis of the observations of this storm will provide important new insight into how these events occur and their effect on the current Mars climate.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN69947 , International Conference on Environmental Systems; Jul 07, 2019 - Jul 11, 2019; Boston, MA; United States
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    3d Crystallographic Orientation of Olivine in Bjurble Chondrules (2019)
    In:  CASI
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    Publication Date: 2019-07-17
    Description: The crystallographic orientations of chondrule minerals can provide important insights into their formation and deformational history. For example, the orientations of the olivine bars and surrounding rim in barred olivine chondrules provide information and on the conditions of crystallization and the orientations and shapes of olivines within porphritic chondrules can record the reactions with the surrounding nebular gas during chondrule formation. Later deformation on the parent body can cause crystal-plastic deformation of chondrule minerals that is evident through their intracrystalline lattice misorientations. Typically these crystal orientations and lattice misorientations are determined using electron backscatter diffraction (EBSD) on thin sections but this gives only a 2D picture for what is actually a 3D texture. While it is possible to combine EBSD with serial sectioning to build a 3D dataset of texture, this is a destructive, time-intensive process. A recent technological development that enables non-destructive, 3D crystallographic orientation measurement is X-ray diffraction contrast tomography (DCT), which uses the X-ray diffraction of the crystal lattice to determine orientation. Originally only possible using monochromatic X-ray beams at 3rd generation synchrotron light sources, DCT has been recently adapted to polychromatic sources of laboratory X-ray microscopes (referred to as Lab-DCT). Up to this point LabDCT has only been applied to large, well-formed crystals of high symmetry (i.e., metals), but we recently acquired DCT datasets for a pair Bjurble chondrules to determine the applicability of the technique to natural, mutlimineralic samples composed predominately of olivine (i.e., chondrules).
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN68323 , Annual Meeting of the Meteoritical Society; Jul 07, 2019 - Jul 12, 2019; Sapporo; Japan
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    Future Planetary Instrument Capabilities Made Possible by Micro- and Nanotechnology (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: A number of new instrument capabilities are currently in maturation for future in situ use on planetary science missions. Moving beyond the impressive in situ instrumentation already operating in planetary environments beyond Earth will enable the next step in scientific discovery. The approach for developing beyond current instrumentation requires a careful assessment of science-driven capability advancement. To this end, two examples of instrument technology development efforts that are leading to new and important analytical capabilities for in situ planetary science will be discussed: (1) an instrument prototype enabling the interface between liquid separation techniques and laser desorption/ionization mass spectrometry and (2) an addressable excitation source enabling miniaturized electron probe microanalysis for elemental mapping of light and heavy elements.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN67623 , SPIE Defense + Commercial Sensing; Apr 14, 2019 - Apr 18, 2019; Baltimore, MD; United States
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    Lynx: Simply Designed for Maximum Science Return (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Astrophysics
    Type: MSFC-E-DAA-TN64281 , Meeting of the American Astronomical Society; Jan 06, 2019 - Jan 10, 2019; Seattle, WA; United States
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    Solar Sails: Traveling the Solar System and Eventually to the Stars! (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Spacecraft Propulsion and Power
    Type: MSFC-E-DAA-TN63467 , Lecture at the International Space University; Jan 24, 2019; Strasbourg; France
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    Searching for the Origin of the High-Energy Emission from GRB 170817A (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Astrophysics
    Type: MSFC-E-DAA-TN64478 , American Astornomical Society (AAS) Meeting; Jan 06, 2019 - Jan 10, 2019; Seattle, WA; United States
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    Aqueous Alteration on Mars (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The occurrence of extensive valley networks and layered deposits of phyllosilicates and sulfates during the late Noachian/Hesperian periods (approx. 3-4 Gyrs) indicates a past martian climate that was capable of maintaining liquid water at the surface. The planets climate drastically changed after these early episodes of water to a drier and colder environment during the Amazonian period (past 3.0 Gyrs). The objective of this paper is to describe aqueous alteration/weathering scenarios on Mars based on observations returned by rover and lander missions. The chemistry of most outcrops, rocks, and soils that have interacted with water has not been extensively changed from average Mars crustal basaltic composition. Little chemical variation suggests closed hydrologic systems were prominent on early Mars and/or the water/rock ratios were low. Open hydrologic systems occur at local scales, e.g., high Si and Ti rocks and soil deposits around a volcanic feature in Gusev crater. Geochemical and mineralogical indicators for aqueous alteration include jarosite and other Fe-sulfates at several locations suggesting acid-sulfate alteration conditions. High Si and Ti rocks, sediments, and soil deposits are consistent with basaltic residues extenively leached by extremely acidic fluids. Variations in the Fe/Mn ratio of fracture veins infilled with sulfate-rich materials suggest changes in redox and/or pH conditions of the migrating fluids. The increase of nanophase iron oxides and salts with depth in several soil pits escavated by the Spirit rovers wheel in Gusev crater suggests the translocation/mobolization of these phases by liquid water. This pedogenic process is the result of limited water movement through the surface sediments during the Amazonian period; however, it is likely that paleosols exist on Mars that formed during the early wetter history of the planet. Soil scientists have the opportunity to continue to (and should) be involved in the exploration of the Red planet.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN63042 , 2018-2019 International Soils Meeting; Jan 06, 2019 - Jan 09, 2019; San Deigo, CA; United States
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    STROBE-X: X-ray Timing & Spectroscopy on Dynamical Timescales from Milliseconds to Years (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: We describe a probe-class mission concept that provides an unprecedented view of the X-ray sky, performing timing and 0.2-30 keV spectroscopy over timescales from microseconds to years. The Spectroscopic Time-Resolving Observatory for Broadband Energy X-rays (STROBE-X) has three key science drivers: (1) measuring the spin distribution of accreting black holes, (2) understanding the equation of state of dense matter, and (3) exploring the properties of the precursors and electromagnetic counterparts of gravitational wave sources. To perform these science investigations, STROBE-X comprises three primary instruments. The first uses an array of lightweight optics (3-m focal length) that concentrate incident photons onto solid state detectors with CCD-level (85-130 eV) energy resolution, 100 ns time resolution, and low background rates to cover the 0.2-12 keV band. This technology is scaled up from NICER, with enhanced optics to take advantage of the longer focal length of STROBE-X. The second uses large-area collimated silicon drift detectors, developed for ESA's LOFT, to cover the 2-30 keV band. These two instruments each provide an order of magnitude improvement in effective area compared with its predecessor (NICER and RXTE, respectively). Finally, a sensitive sky monitor triggers pointed observations, provides high duty cycle, high time resolution, high spectral resolution monitoring of the X-ray sky with ~20 times the sensitivity of the RXTE ASM, and enables multi-wavelength and multi-messenger studies on a continuous, rather than scanning basis. The STROBE-X mission concept is a rapidly repointable observatory in low-Earth orbit, similar to RXTE or Swift, and will be presented to the 2020 Astrophysics Decadal Survey for consideration as a probe-class mission.
    Keywords: Astrophysics
    Type: MSFC-E-DAA-TN64215 , Meeting of the American Astronomical Society (AAS); Jan 06, 2019 - Jan 10, 2019; Seattle,WA; United States
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    Mercury's Internal Structure (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: We describe the current state of knowledge about Mercury's interior structure. We review the available observationalconstraints, including mass, size, density, gravity eld, spin state, composition, and tidal response. These data enablethe construction of models that represent the distribution of mass inside Mercury. In particular, we infer radial prolesof the pressure, density, and gravity in the core, mantle, and crust. We also examine Mercury's rotational dynamicsand the inuence of an inner core on the spin state and the determination of the moment of inertia. Finally, we discussthe wide-ranging implications of Mercury's internal structure on its thermal evolution, surface geology, capture in aunique spin-orbit resonance, and magnetic eld generation.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN67157 , Mercury: The View after MESSENGER; 85-113
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    Estimation of the Seismic Moment Release Rate of Mars from InSight Seismic Data (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Seismicity models for Mars usually estimate the long-term average annual seismic moment rate, and also the average annual event rate. This holds for estimations based on geological evidence (Golombek et al., 1992, Golombek, 2002, Taylor et al., 2013) as well as for models based on thermal evolution and cooling of the Martian interior (Phillips, 1991, Knapmeyer et al., 2006, Plesa et al., 2018). All studies are compatible with the conclusion based on the non-observation of any unambiguous event by Viking (Anderson et al., 1977, Goins & Lazarewicz, 1979) that Martian seismicity lies somewhere between that of the Moon and that of the Earth. We developed tools to derive reasonable estimations of the annual seismic moment rate from a number of events as small as one, provided that the observed events are beyond the global completeness threshold for observable events. Numerical tests as well as evaluation of terrestrial data shows the feasibility of the approach.
    Keywords: Lunar and Planetary Science and Exploration
    Type: MSFC-E-DAA-TN67424 , European Geosciences Union (EGU) General Assembly 2019; Apr 07, 2019 - Apr 12, 2019; Vienna; Austria
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    Wear Trends of the HERMeS Thruster as a Function of Throttle Point (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A series of short-duration (200 h) wear tests were conducted with two Hall Effect Rocket with Magnetic Shielding (HERMeS) technology demonstration units. Front pole covers, cathode keeper, and discharge channel wear were characterized as a function of discharge voltage, magnetic field strength, and chamber pressure. No discharge channel erosion was observed. Inner pole cover erosion was shown to be a weak function of discharge voltage with most erosion occurring at the lowest value, 300 V. The Technology Demonstration Unit (TDU) 3 keeper electrode eroded with each operating condition, with high magnetic field yielding the greatest erosion rate. The TDU-1 keeper electrode exhibited net deposition suggesting its configuration is more consistent with meeting overall HERMeS service life requirements. Ratios of molybdenum to graphite erosion rates suggests, with high uncertainty, that the sputtering ions are originating downstream of the thruster exit plane, striking the surface with small angles of incidence.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/TM-2019-219731 , IEPC?2017?207 , E-19456 , GRC-E-DAA-TN48801 , International Electric Propulsion Conference; Oct 08, 2017 - Oct 12, 2017; Atlanta, GA; United States
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    Fifty Years of Exploring Pluto: from Telescopes to the New Horizons Mission (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Pluto was discovered in 1930 at Lowell Observatory in the belated resumption of a wide-field photographic search originally be-gun at Percival Lowells direction prior to his death in 1916. Photometry in the 1950s established the rotation period of 6.4 hours and a color redder than the Sun, but the mass, density, size and albedo were unknown. Near-infrared photometry in 1976 indicated the presence of CH4 frost, suggestive of a relatively high surface albedo and a diameter comparable to the Moon. The large satellite Charon was discovered in 1978, followed by an epoch of mutual transits and occultations of Pluto and Charon from 1985 to 1990, as viewed from Earth. These events resulted in reliable sizes and masses of the two bodies, as well as the orbit of Charon. The mutual events also demonstrated that Pluto and Charon are in locked synchronous rotation and revolution, a configuration unique among the planets. The atmosphere of Pluto was discovered in 1988 from a stellar occultation observed from the Kuiper Airborne Observatory and ground stations, with indications of a haze layer (or a temperature inversion) in the lower atmosphere. Sub-sequent stellar occultations showed that the extent of the atmosphere is variable on a timescale of a few years. The spectroscopic detection of N2 and CO ice in 1993 demonstrated that the atmosphere must be primarily composed of N2, with CH4 and CO as minor components; the spectroscopic detection of gaseous CH4 was reported in 1994.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN65560 , Lunar and Planetary Science Conference (LPSC); Mar 18, 2019 - Mar 22, 2019; The Woodlands, TX; United States
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    Experimental Insights into the Geochemistry of Mercury (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: With the recent estimate of Mercury's surface composition from the X-Ray Spectrometer and Gamma-Ray Spectrometer that were onboard NASA's MErcury Surface, Space ENvironment, Geochemistry and Ranging (MESSENGER) spacecraft, we now have our first opportunity to directly investigate the compositions of lavas from the planet Mercury and indirectly investigate the chemical make-up of its interior. Results from MESSENGER showed exotic surface compositions with more than 3 wt% sulfur in some lavas and relatively low amounts of iron (less than 3 wt%) across the surface. These striking features are consistent with magmatism occurring under highly reducing conditions which has an impact on the thermal and chemical evolution of a planetary body. Here we'll explore the geochemical evolution of Mercury through a series of experimental studies and discuss the implications of low oxygen fugacity on elemental behavior and magmatic processes.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN65232 , American Chemical Society National Meeting and Expo; Mar 31, 2019 - Apr 04, 2019; Orlando, FL; United States
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    Returning Geological Samples from Mars (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Mars Ascent Vehicle (MAV) Study: Design challenges associated with Mars; Remote; Temperature; Atmosphere; Radiation; Dust. Challenges unique to MAV: No vehicle has ever left the surface of Mars; Completely autonomous; Physical system extremely limited; Martian environment creates a number of issues with traditional propulsion systems.
    Keywords: Lunar and Planetary Science and Exploration
    Type: M19-7197 , IEEE Aerospace Conference (AeroConf 2019); 2ý9 Mar. 2019; Big Sky, MT; United States
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    Qualification of a Hybrid Propulsion System for the Mars Ascent Vehicle (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Spacecraft Propulsion and Power
    Type: M19-7187 , IEEE Aerospace Conference; Mar 03, 2019 - Mar 08, 2019; Big Sky, MT; United States
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    Mars Ascent Vehicle (MAV) Solid Motor Technology Plans (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Recent trades have taken place on solid propulsion options to support a potential Mars Sample Retrieval Campaign. Mass and dimensional requirements for a Mars Ascent Vehicle (MAV) are being assessed. One MAV vehicle concept would utilize a solid propulsion system. Key challenges to designing a solid propulsion system for MAV include low temperatures beyond common tactical and space requirements, performance, planetary protection, mass limits, and thrust vector control system. Two solutions are addressed, a modified commercial commercially available system, and an optimum new concept.
    Keywords: Spacecraft Propulsion and Power
    Type: M18-7069 , IEEE Aerospace Conference; Mar 02, 2019 - Mar 09, 2019; Big Sky, MT; United States
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    Qualification of a Hybrid Propulsion System for the Mars Ascent Vehicle (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Technology for a hybrid based propulsion system is being developed to support a potential Mars Sample Return campaign. A Mars Ascent Vehicle (MAV) concept for launching samples off of Mars, and delivering them to orbit for further transport to Earth may utilize hybrid propulsion due to the predicted favorable low temperature characteristics and high performance of this option. However, the hybrid option is still undergoing technology development to demonstrate these capabilities. Once development of a capable hybrid propulsion system is proven, further work will be required. This will include environmental testing relative to the mission, and integration with the vehicle reaction control systems and payload. Qualification of such a system will be a significant effort. It will require specialized procurements for the propellants and environments involved, and further testing of the more specialized designs. This paper details an estimate of the tasks required to complete development efforts from Technical Readiness Level 5 (TRL5) through qualification. A success based program was formulated to reach the required performance metrics sufficient for a standard Preliminary Design Review (PDR). Using task level inputs from team members cost and schedule were conceived for continued progress to Critical Design Review (CDR), then through Qualification.
    Keywords: Spacecraft Propulsion and Power
    Type: M18-7041 , IEEE Aerospace Conference; Mar 02, 2019 - Mar 09, 2019; Big Sky, MT; United States
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    Development Concepts for Mars Ascent Vehicle (MAV) Solid and Hybrid Vehicle Systems (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The Advanced Concepts Office (ACO) at Marshall Space Flight Center (MSFC) has conducted ongoing studies and trades into options for both hybrid and solid vehicle systems for potential Mars Ascent Vehicle (MAV) concepts for the Jet Propulsion Laboratory (JPL). Two MAV propulsion options are being studied for use in a potential Mars Sample Retrieval (MSR) campaign. The following paper describes the current concepts for hybrid and solid propulsion vehicles for MAV as part of a potential MSR campaign, and provides an overview of the ongoing studies and trades for both hybrid and solid vehicle system concepts. Concepts and options under consideration for vehicle subsystems include reaction control system (RCS), separation, and structures will be described in terms of technology readiness level (TRL), benefit to the vehicle design, and associated risk. A hybrid propulsion system, which uses a solid fuel core and liquid oxidizer, is currently being developed by JPL with support from MSFC. This type of hybrid propulsion vehicle would allow the MAV to be more flexible at the cost of higher complexity, in contrast to the solid propulsion vehicle that is simpler, but allows less flexibility. The solid propulsion vehicle study performed by MSFC in 2018 further refined the solid propulsion system sizing as well as added definition to vehicle subsystem concepts, including the RCS, structures and configuration, interstage and separation, aerodynamics, and power/avionics. The studies were performed using an iterative concept design methodology, engaging subject matter experts from across MSFCs propulsion and vehicle systems disciplines as well as seeking trajectory feedback from analysts at JPL.
    Keywords: Spacecraft Propulsion and Power
    Type: M18-7053 , 2019 IEEE Aerospace Conference; Mar 02, 2019 - Mar 09, 2019; Big Sky, MT; United States
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    Sensor Analysis, Modeling, and Test for Robust Propulsion System Autonomy (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: An approach is presented supporting analysis, modeling, and test validation of operational flight instrumentation (OFI) that facilitates critical functions for the Space Launch System (SLS) main propulsion system (MPS). Certain types of OFI sensors were shown to exhibit highly nonlinear and non-gaussian noise characteristics during acceptance testing, motivating the development of advanced modeling and simulation (M&S) capability to support algorithm verification and flight certification. Hardware model and algorithm simulation fidelity was informed by a risk scoring metric; redesign of high-risk algorithms using test-validated sensor models significantly improved their expected performance as evaluated using Monte Carlo acceptance sampling methods. Autonomous functions include closed-loop ullage pressure regulation, pressurant leak detection, and fault isolation for automated safing and crew caution and warning (C&W).
    Keywords: Spacecraft Propulsion and Power
    Type: AAS 19-103 , M19-7260 , Annual AAS Guidance and Control Conference; Feb 01, 2019 - Feb 06, 2019; Breckenridge, CO; United States
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    Hybrid Fuel Coupling in a Pulsed Z-Pinch Rocket Engine (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The work presented here sought to explore a portion of the parameter space of a hybrid nuclear fuel in regards to ignition and burn by analyzing the effect of initial geometry and thermodynamic conditions. The authors performed 0D power balance and 1D burn wave calculations to determine temperature progression and energy production for defined initial conditions. Geometries examined are representative of concept fuels for a Pulsed Fission-Fusion (PuFF) engine. This work focuses on lithium deuteride and uranium 235 for the fuel since these are seen as leading candidates for PuFF. Presented below is a power balance illustrating a reduction in the energy and density required to breakeven of hybrid fuels in comparison with fusion fuels. Also the impact of fusion and fissile fuel quantities upon initial energies is presented. One can see that the initial energy required to breakeven in a hybrid cylindrical nuclear fuel decreases with decreasing fissile liner thickness, decreasing fusion fuel core radius, and increasing compression ratio of the fusion fuel.
    Keywords: Spacecraft Propulsion and Power
    Type: M19-7200 , NETS Nuclear and Emerging Technologies for Space 2019; Feb 25, 2019 - Feb 28, 2019; Richland, WA; United States
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    Radiation Stability Evaluation of Protein-Based Nanopores for Mars and Europa Missions (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Exploration of our Solar System has revealed a number of locations that are now habitable or could have supported life in the past. One approach to finding life involves detection of informational polymers like deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) that are definitive biosignatures for life as we know it. Alternatively, structural variants of DNA and RNA, collectively termed xenonucleic acids (XNAs) have been shown in the laboratory to behave similarly. Nanopore-based sequencers differ from traditional sequencing technologies in that they do not explicitly require synthesis of DNA before or during analysis. Because of this, nanopore sequencers have been used for the direct sequencing of RNA, and could be used for the detection and analysis of other charged polymers. Here we describe results of exposing the MinION hardware, flow cells, and key reagents to ionizing radiation at doses relevant to Mars and Europa missions (10 to 3000 silicon-equivalent gray).
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN66686
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    Energetic Particles of Cosmic Accelerators I: Galactic Accelerators (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The high-energy universe has revealed that energetic particles are ubiquitous in the cosmos and play a vital role in the cultivation of cosmic environments on all scales. Our pursuit of more than a century to uncover the origins and fate of these cosmic energetic particles has given rise to some of the most interesting and challenging questions in astrophysics. Energetic particles in our own galaxy, galactic cosmic rays (GCRs), engage in a complex interplay with the interstellar medium and magnetic fields in the galaxy, giving rise to many of its key characteristics. For instance, GCRs act in concert with galactic magnetic fields to support its disk against its own weight. GCR ionization and heating are essential ingredients in promoting and regulating the formation of stars and protostellar disks. GCR ionization also drives astrochemistry, leading to the build up of complex molecules in the interstellar medium. GCR transport throughout the galaxy generates and maintains turbulence in the interstellar medium, alters its multi-phase structure, and amplifies magnetic fields. GCRs could even launch galactic winds that enrich the circumgalactic medium and alter the structure and evolution of galactic disks. As crucial as they are for many of the varied phenomena in our galaxy, there is still much we do not understand about GCRs. While they have been linked to supernova remnants (SNRs), it remains unclear whether these objects can fully account for their entire population, particularly at the lower (approximately less than 1 GeV per nucleon) and higher (~PeV) ends of the spectrum. In fact, it is entirely possible that the SNRs that have been found to accelerate CRs merely re-accelerate them, leaving the origins of the original GCRs a mystery. The conditions for particle acceleration that make SNRs compelling source candidates are also likely to be present in sources such as protostellar jets, superbubbles, and colliding wind binaries (CWBs), but we have yet to ascertain their roles in producing GCRs. For that matter, key details of diffusive shock acceleration (DSA) have yet to be revealed, and it remains to be seen whether DSA can adequately explain particle acceleration in the cosmos. This White Paper is the first of a two-part series highlighting the most well-known high-energy cosmic accelerators and contributions that MeV gamma-ray astronomy will bring to understanding their energetic particle phenomena. For the case of GCRs, MeV astronomy will: 1) Search for fresh acceleration of GCRs in SNRs; 2) Test the DSA process, particularly in SNRs and CWBs; 3) Search for signs of CR acceleration in protostellar jets and superbubbles.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN66970
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    NASA's Work in Exoplanet Hunting Satellites and Robotic Servicing of Satellites (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: An overview of three missions connected with NASA's Goddard Space Flight Center at the present time: (1) NASA's flagship mission, the James Webb Space Telescope, is nearing its 2021 launch date. The James Webb, which is considered the successor to the Hubble Space Telescope, will orbit at the Earth-Sun Lagrangian Point Two where it will peer back in time, using infrared detectors, to the beginnings of our Universe. (2) NASA is conducting pioneering work in the field of robotic satellite servicing in earth orbit. The RESTORE-L project, which is slated for a 2021 launch date, is expected to pave the way for the inception of robotic assembly for deep space exploration as well as the commercialization of satellite servicing. (3) The Transiting Exoplanet Survey Satellite (TESS) has been orbiting the Earth actively searching for new planets since April of 2018. The discoveries that TESS has made to-date have benefited from a careful characterization of the refractive lens assemblies on its science instruments. The presentation will provide a detailed description of how the index of refraction of the glasses used to fabricate the TESS lens assemblies were measured at Goddard to an accuracy that enables the ability to make exoplanet discoveries hundreds of light years from Earth.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN66421 , NASA''s Work in Exoplanet Hunting Satellites and Robotic Servicing of Satellites; Mar 27, 2019; Mont Claire, NJ; United States
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    A Multiple Model Based Approach for Deep Space Power System Fault Diagnosis (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Improving protection and health management capabilities onboard the electrical power system (EPS) for spacecraft is essential for ensuring safe and reliable conditions for deep space human exploration. Electrical protection and control technologies on the National Aeronautics and Space Administration's (NASA's) current human space platform relies heavily on ground support to monitor and diagnose power systems and failures. As communication bandwidth diminishes for deep space applications, a transformation in system monitoring and control becomes necessary to maintain high reliability of electric power service. This paper presents a novel approach for on-line power system security monitoring for autonomous deep space spacecraft.
    Keywords: Spacecraft Propulsion and Power
    Type: GRC-E-DAA-TN63587 , GRC-E-DAA-TN57847 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    In Situ Geochronology on Mars and the Development of Future Instrumentation (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Geochronology: More than just rock ages. What are the constraints on the time evolution ofthe dynamic solar system? When did the outerplanets migrate and the asteroid belt lose mass? How did it affect other bodies at that time?
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN67597 , EU-IN-TIME Rise Workshop on Geochronology and Mars Exploration; Apr 08, 2019 - Apr 12, 2019; Austin, TX; United States
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    Time Series Analysis in the Search for Other Worlds Through Transit Photometry (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: The Kepler Mission launched in June 2009 to commence NASA's first mission to search for potentially habitable, Earth-size planets orbiting Sun-like stars. Kepler discovered explanets via the transit method: searching for minute (100 ppm) drops in brightness lasting 1 - 13 hours corresponding to occasions where the planet crosses the face of its host star from Kepler's point of view. The exquisite precision required to carry out the Kepler mission (20 ppm in 6.5 hours) pushed astronomical time series analysis to the limits, and motivated the development of novel algorithmic approaches. Transit signatures of rocky planets are often dwarfed by the intrinsic stellar variability, which is not white noise, and often is non-stationary, and by instrumental systematic effects, which can include transients and electronic artifacts. Surmounting this challenging regime of weak, temporally compact, periodic signals in observation noise with strong systematics and other sources of variability motivated the development of 1) an overcomplete, non-decimated, wavelet-based matched filter to jointly estimate the properties of the non-stationary, non-white observation noise process, and 2) a multi-scale, maximum a posteriori (msMAP) approach to identifying and removing instrumental systematic effects. After over nine years of observations, the Kepler spacecraft finally ran out of fuel in November 2018, ending its data collection activities. Over 2300 planets were discovered by Kepler in its primary mission, and over 355 have been discovered by K2, the repurposed mission that followed Kepler's primary mission after the loss of a second reaction wheel in May 2013. We have ported the Kepler science pipeline for the Transiting Exoplanet Survey Satellite (TESS) Mission, which began science observations in July 2019, and report initial results and performance of the modified science pipeline.The Kepler and TESS Missions are supported by NASA's Science Mission Directorate.
    Keywords: Astrophysics
    Type: ARC-E-DAA-TN63583 , Astronomical Time Series 2019 (NCTS 37182-19); Jan 21, 2019 - Jan 24, 2019; Heidelberg; Germany
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    Distribution of Surface Water Ice on the Moon: An Analysis of Host Crater Ages Provides Insight into the Ages and Sources of Ice at the Lunar South Pole (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN66763 , Lunar and Planetary Science Conference; Mar 18, 2019 - Mar 22, 2019; The Woodlands, TX; United States
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    In-Situ K-Ar Dating Based on UV-Laser Ablation Coupled with a LIBS-QMS System Development, Calibration and Application (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Absolute age determination isnecessary to check and calibratethe relative Martian chronologypresently available from meteoriticcrater counting.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN67097 , Lunar and Planetary Science Conference (LPSC); Mar 18, 2019 - Mar 22, 2019; The Woodlands, TX; United States
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    The Physics of Accretion Onto Highly Magnetized Neutron Stars (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Studying the physical processes occurring in the region just above the magnetic polesof strongly magnetized, accreting binary neutron stars is essential to our understanding of stellarand binary system evolution. Perhaps more importantly, it provides us with a natural laboratoryfor studying the physics of high temperature and density plasmas exposed to extreme radiation,gravitational, and magnetic fields. Observations over the past decade have shed new light on themanner in which plasma falling at near the speed of light onto a neutron star surface is halted. Recentadvances in modeling these processes have resulted in direct measurement of the magnetic fieldsand plasma properties. On the other hand, numerous physical processes have been identified thatchallenge our current picture of how the accretion process onto neutron stars works. Observationand theory are our essential tools in this regime because the extreme conditions cannot be duplicatedon Earth. This white paper gives an overview of the current theory, the outstanding theoreticaland observational challenges, and the importance of addressing them in contemporary astrophysicsresearch.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN66958
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    Gravitational-Wave Astronomy in the 2020s and Beyond: A View Across the Gravitational Wave Spectrum (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: One of the most notable developments since the 2010 Decadal Survey is the addition of gravitationalwaves (GW) to the astronomers' suite of tools for understanding the Universe. LIGO's2015 detection of gravitational waves (Abbott et al. 2016) from the merger of a pair of black holesroughly 30 times the mass of our Sun garnered tremendous excitement from both the public andthe scientific community and raised interesting questions as to the origin of such systems. To datea total of 11 confirmed detections have been announced, including the first GW signals from themerger of neutron stars in 2017 seen by LIGO and Virgo (Abbott et al. 2017). That event wasassociated with a gamma ray burst; the subsequent kilonovae and afterglow was perhaps the mostthoroughly-observed astronomical event of all time (Abbott et al. 2017b). In the coming decades,with continued investment, the ground-based network will continue to improve in both the numberand sensitivity of detectors at high frequencies, pulsar timing arrays such as NANOGrav willuncover stochastic sources of gravitational waves and then single sources at low frequencies, andLISA will begin to probe the mid-frequency band from space. In this white paper, we presenta broad outline of the scientific impact of these facilities in the coming decade and the 2030s,emphasizing the ways in which
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN66963
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    Lynx: Simply Designed for Maximum Science Return (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: MSFC-E-DAA-TN67234 , The Space Astrophysics Landscape for the 2020s and Beyond; Apr 01, 2019 - Apr 03, 2019; Potomac, MD; United States
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    Lunar and Martian Vertical Takeoff & Vertical Landing (VTVL) Pad Concepts (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Landing space craft rocket plume exhaust interactions with the regolith surfaces on the Moon and Mars will result in cratering and regolith particle ejecta traveling at velocities up to 2,000 meters per second in the vacuum surroundings. This phenomenon creates hazards for the spacecraft that is landing or launching and may also cause damage to surrounding assets, personnel and infrastructure. One potential solution to this issue is to construct vertical takeoff and vertical landing (VTVL) pad infrastructure systems which will mitigate these rocket plume exhaust effects. Concepts will be presented for the construction and maintenance of such VTVL pads in lunar and martian environments.
    Keywords: Lunar and Planetary Science and Exploration
    Type: KSC-E-DAA-TN65133 , Caltech Engineering Mechanics Institute Conference (EMI 2019); Jun 18, 2019 - Jun 21, 2019; Pasadena, CA; United States
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    Small-Array Location Capabilities Using the Seismometer to Investigate Ice and Ocean Structure (SIIOS): Implications for an Ocean World Lander (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Ocean worlds have thick icy shells covering subsurface oceans. Due to the potential habitability of the subsurface ocean, Europa has become a target for a potential lander mission. Seismology is the preeminent method for constraining the thickness of an icy shell. The Seismometer to Investigate Ice and Ocean Structure (SIIOS) uses flight-candidate instrumentation to develop approaches for seismic studies of icy bodies. The SIIOS team deployed small aperture seismic arrays on Gulkana Glacier in 2017 and in Northwest Greenland in 2018.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN66598 , Lunar and Planetary Science Conference; Mar 18, 2019 - Mar 22, 2019; The Woodlands, TX; United States
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    Rapid Analysis and Manufacturing Propulsion Technology (RAMPT) (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: The RAMPT project is maturing novel design and manufacturing technologies to increase scale, significantly reduce cost, and improve performance for regeneratively-cooled thrust chamber assemblies, specifically the combustion chamber and nozzle for government and industry programs.
    Keywords: Spacecraft Propulsion and Power
    Type: MSFC-E-DAA-TN66349
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    LYNX: Optics Defined (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Astrophysics
    Type: MSFC-E-DAA-TN64284 , American Astronomical Society Meeting; Jan 06, 2019 - Jan 10, 2019; Seattle, WA; United States
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    Investigating Diurnal Changes in the Normal Albedo of the Lunar Surface at 1064 nm: A New Analysis with the Lunar Orbiter Laser Altimeter (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The thermal environment of the lunar surface is extreme. At the equator, temperatures drop ~300 K between local noon and night. Laboratory studies demonstrate that minerals common to the lunar surface (e.g.,pyroxene, olivine) show spectral changes with respect to temperature in near infrared wavelengths. Over temperature changes equivalent to the lunar thermal environment (T 300K), the reflectance of pure pyroxene samples can vary by a factor of two.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN66761 , Lunar and Planetary Science Conference; Mar 18, 2019 - Mar 22, 2019; The Woodlands, TX; United States
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    Tests of General Relativity and Fundamental Physics with Space-based Gravitational Wave Detectors (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Low-frequency gravitational-wave astronomy can perform precision tests of general relativity and probe fundamental physics in a regime previously inaccessible. A space-based detector will be a formidable tool to explore gravity's role in the cosmos, potentially telling us if and where Einstein's theory fails and providing clues about some of the greatest mysteries in physics and astronomy, such as dark matter and the origin of the Universe.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN67178 , GSFC-E-DAA-TN66949
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    Multi-messenger Astrophysics with Pulsar Timing Arrays: Astro2020 Science White Paper (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Pulsar timing arrays (PTAs) are on the verge of detecting low-frequency gravitational waves (GWs)from supermassive black hole binaries (SMBHBs). With continued observations of a large sampleof millisecond pulsars, PTAs will reach this major milestone within the next decade. Already,SMBHB candidates are being identied by electromagnetic surveys in ever-increasing numbers;upcoming surveys will enhance our ability to detect and verify candidates, and will be instrumentalin identifying the host galaxies of GW sources. Multi-messenger (GW and electromagnetic) obser-vations of SMBHBs will revolutionize our understanding of the co-evolution of SMBHs with theirhost galaxies, the dynamical interactions between binaries and their galactic environments, and thefundamental physics of accretion. Multi-messenger observations can also make SMBHBs `standardsirens' for cosmological distance measurements out to z ~ 0.5 LIGO has already ushered in break-through insights in our knowledge of black holes. The multi-messenger detection of SMBHBs withPTAs will be a breakthrough in the years 2020-2030 and beyond, and prepare us for LISA to helpcomplete our views of black hole demographics and evolution at higher redshifts.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN66951
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    Multimessenger Science Opportunities with mHz Gravitational Waves (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: LISA will open the mHz band of gravitational waves (GWs) to the astronomy community. Thestrong gravity which powers the variety of GW sources in this band is also crucial in a numberof important astrophysical processes at the current frontiers of astronomy. These range fromthe beginning of structure formation in the early universe, through the origin and cosmic evolutionof massive black holes in concert with their galactic environments, to the evolution ofstellar remnant binaries in the Milky Way and in nearby galaxies. These processes and theirassociated populations also drive current and future observations across the electromagnetic(EM) spectrum. We review opportunities for science breakthroughs, involving either direct coincidentEM+GW observations, or indirect multimessenger studies. We argue that for the UScommunity to fully capitalize on the opportunities from the LISA mission, the US efforts shouldbe accompanied by a coordinated and sustained program of multi-disciplinary science investment,following the GW data through to its impact on broad areas of astrophysics. Supportfor LISA-related multimessenger observers and theorists should be sized appropriately for aflagship observatory and may be coordinated through a dedicated mHz GW research center.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN66947
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    A Glint of Light on Broken Glass: Solar System Bombardment History from Apollo Samples (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Legacy of the Apollo samples is the link forged between radiometric ages of rocks and relative ages from crater counts. Lunar impact history innumerous reviews, including NVM-2.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN67098 , Lunar and Planetary Science Conference; Mar 18, 2019 - Mar 22, 2019; The Woodlands, TX; United States
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    Visualization and Analysis of Solar System Small Bodies with NASA's Solar System Treks Project (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: In its investigations of Vesta and Ceres, NASAs Dawn mission has returned spectacular data detailing the surfaces of these two prominent small bodies in our Solar Systems asteroid belt. In order to greatly facilitate dissemination, visualization, and analysis of this data, and public understanding of the mission, the Dawn mission has partnered with NASAs Solar System Treks Project (SSTP). SSTP has recently released an update to the Vesta Trek online portal (https://trek.nasa.gov/vesta/) and has released a new Ceres Trek portal (https://trek.nasa.gov/ceres/). This presentation will showcase the use of the Ceres Trek and Vesta Trek portals and demonstrate how they can be used to visualize and analyze particularly interesting landforms such as the pitted terrain on Vesta and relic cryovolcanoes on Ceres. We will also demonstrate the new VR capability that has been added to the portals, allowing users to generate their own virtual reality flyovers for any user-defined paths along the bodies surfaces. In addition to highlighting the portals for Ceres and Vesta, the presentation will preview additional portals being planned/developed for other small bodies. NASA and JAXA have requested the development of a portal for the asteroid Ryugu to facilitate dissemination, visualization, and analysis of data from Japans Hayabusa2 mission, and a portal for Mars moon Phobos in support of mission planning for Japans MMX mission. We are also planning a portal for the asteroid Bennu with data from the OSIRIS-Rex mission. All of these products are efforts in the NASA Solar System Treks Project (SSTP), available at https://trek.nasa.gov. NASA's Solar System Trek online portals provide web-based suites of interactive data visualization and analysis tools to enable mission planners, planetary scientists, students, and the general public to access mapped data products from past and current missions for a growing number of planetary bodies including the Moon, Mars, Vesta, etc. These portals are being used for site selection and analysis by NASA and a number of its international partners, supporting upcoming missions. In addition to demonstrating the capabilities of selected portals in this presentation, we will solicit input from the community for ideas for future enhancements to the portals.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN65591 , Japan Geoscience Union (JpGU) Meeting 2019; May 26, 2019 - May 30, 2019; Chiba; Japan
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    Searching for Martian Bio-Indicators and Extant Life Using Spacecraft (2019)
    In:  CASI
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    Publication Date: 2019-07-19
    Description: Current environmental conditions at the surface of Mars are hostile to life as we know it, but the near subsurface may well provide sufficient shielding to harbor simple life forms. This discussion focuses on methane which can be produced either abiotically or by microbial life and possible geological or biological sources for that methane in the subsurface.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN64269 , Mars Extant Life: Whatýs Next conference; Nov 05, 2019 - Nov 08, 2019; Carlsbad, NM; United States
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    Breaking the Cost Curve: Applying Lessons Learned from the James Webb Space Telescope Development (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: This paper looks at the key programmatic and technical drivers of the James Webb Space Telescope and assesses ways to building more cost-effective telescopes in the future. The paper evaluates the top level programmatics for JWST along with the key technical drivers from design through integration and testing. Actual data and metrics from JWST are studied to identify what ultimately drove cost on JWST. Finally, the paper assesses areas where applying lessons learned can reduce costs on future observatories and will provide better insights into critical areas to optimize for cost.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN65820
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    Energetic Particles of Cosmic Accelerators II: Active Galactic Nuclei and Gamma-ray Bursts (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The high-energy universe has revealed that energetic particles are ubiquitous in the cosmos and play a vital role in the cultivation of cosmic environments on all scales. Our pursuit of more than a century to uncover the origins and fate of these cosmic energetic particles has given rise to some of the most interesting and challenging questions in astrophysics. Within our own galaxy, we have seen that energetic particles engage in a complex interplay with the galactic environment and even drive many of its key characteristics (for more information, see the first white paper in this series). On cosmological scales, the energetic particles supplied by the jets of active galactic nuclei (AGN) are an important source of energy for the intracluster and intergalactic media, providing a mechanism for regulating star formation and black hole growth and cultivating galaxy evolution (AGN feedback). Gamma-ray burst (GRB) afterglows encode information about their circumburst environment, which has implications for massive stellar winds during previous epochs over the stellar lifecycle. As such, GRB afterglows provide a means for studying very high-redshift galaxies since GRBs can be detected even if their host galaxy cannot. It has even been suggest that GRB could be used to measure cosmological distance scales if they could be shown to be standard candles. Though they play a key role in cultivating the cosmological environment and/or enabling our studies of it, there is still much we do not know about AGNs and GRBs, particularly the avenue in which and through which they supply radiation and energetic particles, namely their jets. Despite the enormous progress in particle-in-cell and magnetohydrodynamic simulations, we have yet to pinpoint the processes involved in jet formation and collimation and the conditions under which they can occur. For that matter, we have yet to identify the mechanism(s) through which the jet accelerates energetic particles is it the commonly invoked diffusive shock acceleration process or is another mechanism, such as magnetic reconnection, required? Do AGNs and GRBs accelerate hadrons, and if so, do they accelerate them to ultra-high energies and are there high-energy neutrinos associated with them? MeV gamma-ray astronomy, enabled by technological advances that will be realized in the coming decade, will provide a unique and indispensable perspective on the persistent mysteries of the energetic universe. This White Paper is the second of a two-part series highlighting the most well-known high-energy cosmic accelerators and contributions that MeV gamma-ray astronomy will bring to understanding their energetic particle phenomena. Specifically, MeV astronomy will: 1. Determine whether AGNs accelerate CRs to ultra-high energies; 2. Provide the missing pieces for the physics of the GRB prompt emission; 3. Measure magnetization in cosmic accelerators and search for acceleration via reconnection.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN66972
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    The Sedimentary History of Mars as Observed by Rovers (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Mars has a sedimentary history that spans billions of years. Orbital images have allowed for the identification of vast regional sedimentary deposits that can be traced over 100s of kilometers and are 100s of meters thick including localized alluvial, deltaic, and lacustrine deposits. Detections of secondary minerals in these deposits from orbital spectroscopy suggest the aqueous history of early Mars varied as a function of space and time. Orbital observations, however, provide a simplified and incomplete picture of Mars sedimentary history because measurements for inferring sediment transport and deposition, such as lithology, grain size, and internal structures, and measurements for inferring sediment source and aqueous alteration, such as outcrop-scale mineralogic and geochemical composition and diagenetic features, cannot be identified from orbit. Rover observations have significantly enhanced our view of ancient and modern sedimentary environments on Mars, resulting in detailed reconstructions of paleo-environments and habitability.
    Keywords: Lunar and Planetary Science and Exploration
    Type: LPI Contrib. No. 2132 , JSC-E-DAA-TN66078 , Lunar and Planetary Science Conference (LPSC 2019); 18ý22 Mar. 2019; The Woodlands, TX; United States
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    Saponite Dissolution Experiments and Implications for Mars (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Recent work suggests that the mineralogical sequence of the Murray formation at Gale crater may have resulted from diagenetic alteration after sedimentation, or deposition in a stratified lake with oxic surface and anoxic bottom waters. Fe-containing clay minerals are common both at Gale crater, and throughout the Noachian-aged terrains on Mars. These clay minerals are primarily ferric (Fe3+), and previous work suggests that these ferric clay minerals may result from alteration of ferrous (Fe2+) smectites that were oxidized after deposition. The detection of trioctahedral smectites at Gale crater by CheMin suggests Fe2+ smectite was also deposited during the early Hesperian. However, due to their sensitivity to oxygen, Fe2+ smectites are difficult to analyze on Earth and very few saponite dissolution rates exist in the literature. To the best of our knowledge, no experiments have measured the dissolution rates of ferrous saponites under oxidizing and reducing conditions. In order to better understand the characteristics of water-rock interaction at Gale crater, particularly the oxidation state, we report our results to date on ongoing syntheses of ferrous and magnesium saponites and dissolution experiments of natural saponite under ambient conditions. Future experiments will include the dissolution of synthetic ferric, ferrous, and magnesium saponites under oxidizing and anoxic conditions at a range of pH values.
    Keywords: Lunar and Planetary Science and Exploration
    Type: LPI Contrib. No. 2132 , JSC-E-DAA-TN66074 , Lunar and Planetary Science Conference (LPSC 2019); 18ý22 Mar. 2019; The Woodlands, TX; United States
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    Interpreting Aqueous Alteration in the Murray Formation Using Reactive Transport Modeling (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Abundant evidence for liquid water exists at Gale crater, Mars. However, the characteristics of past water remain an area of active research. The first exposures of the Murray formation in Gale crater, Mars (Fig. 1) were studied with four samples analyzed using CheMin: Buckskin, Telegraph Peak, Mojave, and Confidence Hills. Analyses indicate differences in mineralogy and chemistry between the samples which have been attributed to changes in pH and oxidation state of depositional and diagenetic environments. Recent work also suggests that hydrothermal fluids may have been present based on the presence of Se, Zn, Pb, and other elements.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN66065 , Lunar and Planetary Science Conference; Mar 18, 2019 - Mar 22, 2019; Woodlands, TX; United States
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    Spectral Properties of Hydrated Poorly Crystalline Materials for Spectral Analysis of the Moon and Mars (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Visible/near-infrared (VNIR) reflectance spectra of both Mars [1] and the Moon [2] include hydration bands that vary across the planet and are not well explained in some cases. Poorly crystalline phases have been found at ~30-70 wt.% by CheMin in Gale crater, Mars in all samples measured to date [3]. Here we report on VNIR reflectance spectra of a large collection of amorphous and poorly crystalline materials. These include opal, allophane, imogolite, iron hydroxides/ oxyhydroxides (FeOx), and several synthetic materials containing Si, Al and/or Fe. All of these contain hydration bands due to water and OH that can be used to identify these materials remotely on planetary bodies.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN66032 , Lunar and Planetary Science Conference; Mar 18, 2019 - Mar 22, 2019; Woodlands, TX; United States
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    Isolation and Monitoring of Cleanroom-Associated Microbial Contaminates From Geological Collections (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Microbial contamination is of particular interest to geological curation as many microorganisms can change mineral composition and produce compounds used as biosignatures used for the detection of life. Microbial cells can change the mineral composition of rocks through organic acid production and direct enzymatic oxidation/reduction of transition metals. Enzymatic oxidation of iron and manganese can occur at a rate several orders of magnitude faster than under abiotic conditions and produce highly reactive nanoparticle- sized oxides that can react and sorb other metals and organic compounds. Many fungi can also produce organic acids that dissolve and chelate mineral matrices chemically reducing and dissolving rock surfaces. Finally, several common soil-associated bacteria and fungi produce secondary metabolites that contain unusual amino acid analogs and non-ribosomal peptides containing both L- and D- chirality used in characterizing carbonaceous chondrites and the detection of extraterrestrial life.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN65757 , Lunar and Planetary Science Conference; Mar 18, 2019 - Mar 22, 2019; Woodlands, TX; United States
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    Remarkable Diversity of Refractory Inclusions in the Miller Range 090019 CO3.1 Chondrite (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: We have characterized the mineralogy, textures, bulk compositions, modal abundances and some mineral compositions in a suite of approximately 140 refractory inclusions from the MIL090019 carbonaceous chondrite. All of these 140 inclusions are found in a single thin section of this CO3.1 chondrite. These inclusions range from grossite- and hibonite-rich varieties, melilite-, spinel-, fassaite-diopside- and anorthite-rich types, and include a subset of aluminous AOAs (amoeboidal olivine aggregates). Grossite- and hibonite-bearing inclusions were discussed briefly in previous abstracts. X-ray mapping by energy dispersive spectrometry has permitted us to extract the bulk compositions of these inclusions from hyperspectral x-ray datasets. The bulk compositions of these inclusions represent the full range of recognized CAI (Calcium-Aluminumrich Inclusions) types.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN65245 , Lunar and Planetary Science Conference (LPSC 2019); 18ý22 Mar. 2019; The Woodlands, TX; United States
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    The CAESAR New Frontiers Mission: 1. Expected Nature of the Returned Comet Sample (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Comets are time capsules from the birth of our Solar System that record pre-solar history, the initial stages of planet formation, and the sources of prebiotic organics and volatiles for the origin of life. These capsules can only be opened in laboratories on Earth. CAESAR (Comet Astrobiology Exploration Sample Return)s sample analysis objectives are to understand the nature of Solar System starting materials and how these components came together to form planets and give rise to life. Examination of these comet nucleus surface samples in laboratories around the world will also provide ground truth to remote observations of the innumerable icy bodies of the Solar System.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN64974 , Lunar and Planetary Science Conference (LPSC 2019); 18ý22 Mar. 2019; The Woodlands, Texas; United States
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    Trace Element Abundances of Olivine-Hosted Melt Inclusions in Shergottites Northwest Africa 7397 and Robert Massif 04262 (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Olivine-hosted melt inclusions (MIs) may retain trapped parent magma compositions as well as record progressive differentiation while magmas crystallize and ascend towards the surface [1,2 and references therein]. Major element compositions of the MIs, especially Fe and Mg, can be affected by post-entrapment re-equilibration with their host olivine [1,2]. Therefore, Fe/Mg ratio correction is required to obtain MI bulk compositions following equilibrium with their host olivine. Partition coefficients of most of the trace elements in olivine are very low (i.e. DOL/melt〈0.001). Thus, ratios of trace elements of olivine-hosted MIs are unlikely to be affected by post-entrapment re-equilibration and no correction is necessary [2]. Hence, tracking trace element behavior in MIs may constrain the composition of the parent magma and its evolution yielding insights on magma differentiation of shergottites. However, analyzing MIs for chemical compositions is a challenging task due to their low abundances and small sizes. Using a highly sensitive and precise micro-beam technique is essential to examine olivine-hosted MIs in order to measure trace element abundances. For this purpose, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is an excellent tool due to its wide range of laser spot sizes (1-150 m), ability to obtain raster analysis (several mm2) and lower detection limits (0.1 ppb) [3].
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN64818 , Lunar and Planetary Science Conference; Mar 18, 2019 - Mar 22, 2019; Woodlands, TX; United States
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    The 2008 Mars Phoenix Lander Thermal and Evolved Gas Analyzer (TEGA) Dataset: Placing Easily Interpretable Evolved Gas Data on the Planetary Data System (PDS) (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The Phoenix Scout Lander mission investigated the north polar region of Mars in 2008 with the goal to study the history of water, assess the past/present Martian climate, search for organics, and evaluate the potential for past/present microbial habit-ability on Mars. To accomplish this goal, the Phoenix Landers Thermal and Evolved-Gas Analyzer (TEGA) instrument assessed the gas composition of the Martian atmosphere and evaluated the mineralogy of the Martian regolith. The TEGA instrument consisted of eight small ovens connected to a 4 channel magnetic sector mass spectrometer. The ovens heated soil samples from ambient to 1000C where the gases (e.g., H2O, CO2, etc.) evolved from thermal decomposition of mineral phases were analyzed by the mass spectrometer. Minerals thermally decomposed at characteristic temperatures and the evolving gases indicated the presence of perchlorate, carbonate, and hydrated phases in the Phoenix landing site soils.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN64834 , 2019 Lunar and Planetary Science Conference (LPSC); Mar 18, 2019 - Mar 22, 2019; Woodlands, TX; United States
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    Lunar Reconnaissance Orbiter: Enabling CLPS Mission Success (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN66338 , Commercial Lunar Payload Services Program (CLPS); Mar 01, 2018; Greenbelt, MD; United States
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    The Large UV/Optical/Infrared Surveyor (LUVOIR): Decadal Mission Concept Study Update (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: In preparation for the 2020 Decadal Survey in Astronomy and Astrophysics, NASA commissioned the study of four large mission concepts: the Large UV/Optical/Infrared Surveyor (LUVOIR), the Habitable Exoplanet Imager (HabEx), the far-infrared surveyor Origins Space Telescope (OST), and the X-ray surveyor Lynx. The LUVOIR Science and Technology Definition Team (STDT) has identified a broad range of science objectives for LUVOIR that include the direct imaging and spectral characterization of habitable exoplanets around sun-like stars, the study of galaxy formation and evolution, the exchange of matter between galaxies, star and planet formation, and the remote sensing of Solar System objects. The LUVOIR Study Office, located at NASA's Goddard Space Flight Center (GSFC), is developing two mission concepts to achieve the science objectives. LUVOIR-A is a 15-meter segmented-aperture observatory that would be launched in an 8.4-m extended fairing on the Space Launch System (SLS) Block 2 configuration. LUVOIR-B is an 8-meter unobscured segmented aperture telescope that fits in a smaller, conventional 5-meter fairing, but still requires the lift capacity of the SLS Block 1B Cargo vehicle. Both concepts include a suite of serviceable instruments: the Extreme Coronagraph for Living Planetary Systems (ECLIPS), an optical/near-infrared coronagraph capable of delivering 10 (sup minus10) contrast at inner working angles as small as 2 lambda divided by D; the LUVOIR UV Multi-object Spectrograph (LUMOS), which will provide low- and medium-resolution UV (100-400 nanometer) multi-object imaging spectroscopy in addition to far-UV imaging; the High Definition Imager (HDI), a high-resolution wide-field-of-view NUV-Optical-NIR imager. LUVOIR-A also has a fourth instrument, Pollux, a high-resolution UV spectro-polarimeter being contributed by Centre National d'Etudes Spatiales (CNES). This paper provides an overview of the LUVIOR science objectives, design drivers, and mission concepts.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN65070 , IEEE Aerospace Conference (AeroConf 2019); 2ý9 Mar. 2019; Big Sky, MT; United States
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    Space Power Heritage Study Final Results (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: NASA space missions have long employed Radioisotope Power Systems (RPS) and solar-based power generation architectures. RPS have been used to enable or significantly enhance missions that venture deep into the solar system to distances from the sun which can make using solar architectures unfeasible and to areas where the sun is obscured due to shadows or atmospheric phenomena. The destination, however, is not the absolute factor of the determination of RPS or solar. This is highlighted by the Jupiter missions Galileo and Juno, which employed RPS and solar architectures, respectively. When baselining either RPS or solar architectures for a planetary mission, numerous factors must be considered, including scientific objectives, cost, schedule, and mass just to name a few. In an effort to better understand the decision-making process and provide insight for potential future missions, the NASA RPS Program Office tasked The Aerospace Corporation (Aerospace) to study historical missions that used RPS and solar architectures. Data was collected for a variety of RPS and solar missions to look for possible trends from the selected implementation. Additionally, mission case studies were developed based on interviews with mission personnel who were responsible for defining the power architecture of their mission. Informed by the data collected and case studies, two Measures of Effectiveness (MoEs) were produced: one based on cost of RPS versus solar, and one based on science mission cost effectiveness. The final results of this study have been captured in this briefing package which is available for full and open release. Additionally, a final report document also provides the same details of this package. This briefing package also includes an appendix which contains data not for public release which was used to provide detailed answers to questions raised during this study. The results of these inquiries are discussed in the report, but the proprietary data is not included. Finally, an executive summary package is also publicly available which was used to present the results of the study at the 2018 Aerospace Space Power Workshop.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/CR-2019-220039 , ATR-2018-02688 , GRC-E-DAA-TN62337
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    Thermal System Sizing Comparison of a PEM and Solid Oxide Fuel Cell Systems on Mars (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Power production is a key aspect to any Mars mission. One method for providing power throughout the day/night cycle, or to satisfy short-duration high-output power needs, is to utilize a regenerative fuel cell system for providing energy storage and nighttime or supplemental power. This study compares the total system mass for two types of fuel cell systems, proton exchange membrane (PEM) and solid oxide (SO), sized to provide 10 kW of electrical output power in the Mars environment. Two operating locations were examined; one near the equator at 4 S latitude and one the higher northern latitude of 48N. The systems were sized to operate throughout the year at these locations, where the radiator was sized for the worst-case warm condition and the insulation was sized for the worst-case cold condition. Using the selected system parameters, the results for both latitudes showed that the lightest system was the SO fuel cell with a PEM electrolyzer. This was mainly due to the higher operational temperature of the SO system enabled a significantly smaller radiator mass compared to that of the PEM fuel cell system. However, there was a significant difference in mass for the PEM system when operated near the equator as compared to the higher northern latitude. For the 10-kW output system this difference in mass was just under 100 kg.
    Keywords: Spacecraft Propulsion and Power
    Type: GRC-E-DAA-TN62192 , NASA/TM-2019-220019
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    Architecture and Dynamics of Kepler's Multi-Transiting Planet Systems.III. Comprehensive Investigation Using All Four Years of Kepler Mission Data (2019)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: We study the orbital architectures of planetary systems orbiting within 1 AU of their stars by analyzing the ensemble of Kepler systems having two or more planet candidates. We use data from the entire Kepler mission, and in many cases we apply improved analysis techniques (e.g., replacing histograms by top-hat Kernel Density Estimators that avoid the loss of information resulting from choosing a particular phase for the bin boundaries) to extend and enhance the studies of Lissauer et al. (2011, ApJS 197, 8) and Fabrycky et al. (2014, ApJ 790, 146).These data show ~ 1700 transiting planet candidates in 〉 600 multiple-planet systems, far more than were available for our previous two studies. The increased numbers and better information about planetary radii and the properties of stellar hosts made possible by Gaia DR2 allow more statistically-robust analyses of the entire ensemble of Kepler multis as well as independent analyses of subsets of the population. We are thus able to contrast the dynamical configurations of small and large planets, short-period and longer-period planets, and planets orbiting various types of host stars. We reinforce our previous findings that most pairs of planets within the same system are neither in nor near low-order mean motion resonances and that there is a substantial excess of planets having period ratios slightly larger than those of first-order mean-motion resonances. However, neglecting three systems whose planets are locked in 3- body resonances and summing over all first-order mean motion resonances, the deficit of planet pairs with period ratios just narrow of resonance is as large as the excess of planets wide of resonance (within statistical uncertainties), suggesting that overall there is no overall excess of planet pairs in the vicinity of resonance. Other aspects of our study, including estimates of the typical relative inclinations of planetary orbits and their variations as functions of orbital period, planet sizes and stellar properties, are in progress, with results expected to be available for presentation by the time of the conference.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN65422 , Kepler & K2 Svience Conference; Mar 04, 2019 - Mar 08, 2019; Glendale, CA; United States
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    In Space Assembled Telescope (ISAT) Study Preliminary Findings (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: When is it advantageous to assemble telescopes in space rather than deploying them from launch vehicle fairings? This question forms the crux of the objectives of a NASA study we have been conducting in collaboration with colleagues from different NASA centers, industry and academia. In this study, we have engaged a broad cross section of experts from the various fields of optics engineering, that is, telescope design and instrument design, structure and thermal engineering, robotics, launch system engineering, orbital mechanics, integration and testing, astrophysics, and NASA programmatics among others. Initial efforts began with a quick review of the current state of art of the component technologies that contribute towards an in-space assembled telescope. Then, leveraging the collective expertise of the diverse group of experts, we formulated a reference telescope design and attempted to develop a baseline approach to modularize the telescope into components amenable for robotic assembly. The group identified different trades associated with modularization and also developed a set of criteria to discern between the different options as revealed by the trades. Based on the modularization of the telescope, we will assess the impact of various launch vehicles, orbits for assembly and operation, robotic systems and operational approaches, and other related variables. From this, a concept to assemble the reference telescope in space from modular components will be developed. Based on this concept, and definition of the modules, we will develop a mission lifecycle plan for an assembled telescope over different phases of preliminary design, detailed design, assembly-test-and-integration, and in space operations. The mission lifecycle plan will be used to evaluate cost and risk implications of in-space assembly toward answering our fundamental question of the advantages, if any, of assembling a telescope in space as compared to self-deployment. In this paper, we summarize the objectives of the study, a review of the status of the underlying component technologies, a description of the methodology, including three different multi-day technical interchange meetings (TIMs), summary of findings from the TIMs and other related activities. In addition, a detailed description of the various factors that impact in-space assembly, their interplay and criteria for discerning among them, a preliminary description of the life cycle plan, including the test and integration plan, and initial observations on cost and risk implications will be included in the paper.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN58571 , International Conference for Aerospace Experts, Academics, Military Personnel, and Industry Leaders; Mar 02, 2019 - Mar 09, 2019; Big Sky, MT; United States
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    Exploration of Atmospheric Entries at Uranus & Neptune with HEEET as Heatshield TPS (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: One important observation from the recent Ice Giants Study sponsored by NASA was that the predicted and margined thicknesses of HEEET (new NASA TPS technology) were much greater than could be woven with the currently established loom capabilities. Since the cost of a loom upgrade would be substantial, the present work explores the entry trajectory space to determine what combinations of entry parameters would result in HEEET thicknesses that fit within the existing loom infrastructure. Toward this end, the entry trajectory space, parameterized by ballistic coefficient and entry flight path angle, was systematically explored for 45 sphere-cone geometries of 3 different radii 0.2 m, 0.3 m, and 0.4 m which covered the range from Galileo-derived probes considered in the Ice Giants Study, and a follow-on study on the possibility of using a single probe architecture (in terms of size and mass) for various destinations, including Venus, Saturn, Uranus, and Neptune. The entry velocities, latitudes, and azimuths at Uranus and Neptune used in the present work were taken from the Ice Giants Study. For each 3D OF trajectory generated by a NASA Ames in-house code, TRAJ, the material response and thickness were computed using another NASA Ames code, FIAT, along with a margins policy proposed by the HEEET project. In the present work, ballistic coefficients ranging from 200 kg/sqm to 350 kg/sqm were considered along with entry flight path angles ranging from -16 to -36 (primarily to allow deceleration loads to vary between 50 g and 200 g).
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN65499 , Workshop on In Situ Exploration of the Ice Giants; Feb 25, 2019 - Feb 27, 2019; Marseille; France
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    TESS Data Release Notes: Sector 12, DR17 (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-26
    Description: This release note discusses the science data products produced by the Science Processing Operations Center at Ames Research Center from Sector 12 observations made with the TESS spacecraft and cameras as a means to document instrument performance and data characteristics.
    Keywords: Astrophysics
    Type: NASA/TM-2019-220297 , ARC-E-DAA-TN71061
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  • 94
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    Hybrid Fuel Coupling in a Pulsed Z-Pinch Rocket Engine (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The work presented here sought to explore a portion of the parameter space of a hybrid nuclear fuel in regards to ignition and burn by analyzing the effect of initial geometry and thermodynamic conditions. The authors performed 0D power balance and 1D burn wave calculations to determine temperature progression and energy production for defined initial conditions. Geometries examined are representative of concept fuels for a Pulsed Fission-Fusion (PuFF) engine. This work focuses on lithium deuteride and uranium 235 for the fuel since these are seen as leading candidates for PuFF. Presented below is a power balance illustrating a reduction in the energy and density required to breakeven of hybrid fuels in comparison with fusion fuels. Also the impact of fusion and fissile fuel quantities upon initial energies is presented. One can see that the initial energy required to breakeven in a hybrid cylindrical nuclear fuel decreases with decreasing fissile liner thickness, decreasing fusion fuel core radius, and increasing compression ratio of the fusion fuel.
    Keywords: Spacecraft Propulsion and Power
    Type: M18-7082 , Nuclear and Emerging Technologies for Space 2019; Feb 25, 2019 - Feb 28, 2019; Richland, WA; United States
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  • 95
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    Apollo 50 Next Giant Leap (2019)
    In:  Other Sources
    Details
    Publication Date: 2019-07-25
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: MSFC-E-DAA-TN70754 , Anniversary Apollo NASA Spinoff Presentation; Jul 19, 2019; Ronks, PA; United States
    Format: text
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  • 96
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    Seismometer to Investigate Ice and Ocean Structure (SIIOS) (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-24
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: MSFC-E-DAA-TN70725 , IUGG General Assembly; Jul 08, 2019 - Jul 18, 2019; Montréal, Québec; Canada
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  • 97
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    Recreating in Situ Measurements of Potentially Hazardous Meteoroids (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-23
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: M19-7424 , Meteoroids 2019; Jun 17, 2019 - Jun 21, 2019; Bratislava, Slovakia
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  • 98
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    Bolides Detected by GLM and Ground-Based Meteor Networks (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: M19-7432 , Meteoroids 2019; Jun 17, 2019 - Jun 21, 2019; Bratislava, Slovakia; Czechoslovakia
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  • 99
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    Meteor Shower Fluxes with All Sky Cameras (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: M19-7416 , Meteoroids 2019; Jun 17, 2019 - Jun 21, 2019; Bratislava, Slovakia
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  • 100
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    Laboratory Scale Testing of Ignition Overpressure for Space Vehicle Launch Pad Environments (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A scale model of a NASA representative space vehicle is used to develop a refined estimate of the transient pressure loads that are expected to form at the base of the vehicle in the event of a vapor cloud explosion. Flammable vapor clouds are known to form prior to engine startup due to the significant amount of unburned hydrogen that is ejected from the combustion chamber. In the event of a vapor cloud explosion, the vehicle and payload must be able to withstand the resulting overpressure waves. The study comprises an array of pressure sensors located along the base heat shield of the scale model space vehicle as well as the interior wall and throat plug plane of the solid rocket booster. A spark source generator is used to simulate the overpressure wave produced by a vapor cloud explosion while measurements are acquired with and without the effect of a mobile launcher. Time- resolved schlieren images of the simulated vapor cloud explosion reveal the path and impact of both the initial wave and several reflected waves on the various components at the base of the space vehicle. In some instances, the reflected waves superpose to create waves that are higher in amplitude than the initial overpressure wave. A time frequency analysis of the pressure waveforms measured inside the solid rocket booster reveal a ring down tone corresponding to a standing wave that is four times the length of the nozzle.
    Keywords: Spacecraft Propulsion and Power
    Type: M19-7404 , AIAA/CEAS Aeroacoustics Conference; May 20, 2019 - May 23, 2019; Delft; Netherlands
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