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  • Lunar and Planetary Science and Exploration  (16)
  • Economics, Sociology  (2)
  • Geophysics  (1)
  • 1
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    Curtailed conversations (2018)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2018-06-01
    Keywords: Economics, Sociology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Warming stresses developing countries (2017)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2017-12-22
    Keywords: Economics, Sociology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Insolation Effects on Lunar Hydrogen: Observation from the LRO LEND and LOLA Instruments (2011)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: The Moon's polar permanent shadow regions (PSR) have long been considered the unique repository for volatile Hydrogen (H) Largely, this was due to the extreme and persistently cold environment that has been maintained over eons of lunar history. However, recent discoveries indicate that the H picture may be more complex than thc PSR hypothesis suggests. Observations by the Lunar Exploration Neutron Detect (LEND) onboard the Lunar Reconnaissance Orbiter (LRO) indicate some H concentrations lie outside PSR. Similarly, observations from Chandraayan-l's M3 and Deep Impact's EPOXI near infra-red observations indicate diurnal cycling of volatile H in lower latitudes. These results suggest other geophysical phenomena may also play a role in the Lunar Hydrogen budget. In this presentation we review the techniques and results from the recent high latitude analysis and apply similar techniques to equatorial regions. Results from our low latitude analysis will be reported. We discuss interpretations and implications for Lunar Hydrogen studies
    Keywords: Lunar and Planetary Science and Exploration
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  • 4
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    Global Maps of Lunar Neutron Fluxes from the LEND Instrument (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The latest neutron spectrometer measurements with the Lunar Exploration Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter (LRO) are presented. It covers more than 1 year of mapping phase starting on 15 September 2009. In our analyses we have created global maps showing regional variations in the flux of thermal (energy range 〈 0.015 eV) and fast neutrons (〉0.5 MeV), and compared these fluxes to variances in soil elemental composition, and with previous results obtained by the Lunar Prospector Neutron Spectrometer (LPNS). We also processed data from LEND collimated detectors and derived a value for the collimated signal of epithermal neutrons based on the comparative analysis with the LEND omnidirectional detectors. Finally, we have compared our final (after the data reduction) global epithermal neutron map with LPNS data.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN9082 , Journal of Geophysical Research Planets (ISSN 2169-9100); 117; E12
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  • 5
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    The Lunar Reconnaissance Orbiter: Plans for the Extended Science Phase (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Lunar Reconnaissance Orbiter spacecraft (LRO), launched on June 18, 2009, began with the goal of seeking safe landing sites for future robotic missions or the return of humans to the Moon as part of NASA's Exploration Systems Mission Directorate (ESMD). In addition, LRO's objectives included the search for surface resources and to investigate the Lunar radiation environment. Having marked the two-year anniversary, we will review here the major results from the LRO mission for both exploration and science and discuss plans and objectives going forward including plans for an extended science phase out to 2014.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC.CPR.6360.2012 , 43rd Lunar and Planetary Science Conference; Mar 19, 2012 - Mar 23, 2012; The Woodlands, TX; United States
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  • 6
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    Correlated Observations of Epithermal Neutrons and Polar Illumination for Orbital Neutron Detectors (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: We correlate Lunar Reconnaisance Orbiter's (LRO) Lunar Exploration Neutron Detector (LEND) and the Lunar Prospector Neutron Spectrometer's (LPNS) orbital epithermal neutron maps of the Lunar high-latitudes with co-registered illumination maps derived from the Lunar Orbiter Laser Altimeter (LOLA) topography. Epithermal neutron count rate maps were derived from the LEND: 1) Collimated Sensor for Epithermal Neutrons, CSETNI-4 2) Uncollimated Sensor for Epithermal Neutrons, SETN and the Uncollimated Lunar Prospector: 3) Low-altitude and 4) High-altitude mapping phases. In this abstract we illustrate 1) and 3) and include 2) and 4) in our presentation. The correlative study provides unique perspectives on the regional epithermal neutron fluences from the Lunar polar regions under different detector and altitude configurations.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC.CPR.6357.2012 , Lunar and Planetary Science Conference 2012; Mar 19, 2012 - Mar 24, 2012; The Woodlands, TX; United States
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  • 7
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    Lunar Reconnaissance Orbiter (LRO) Observations with the Lunar Exploration Neutron Detector (LEND): Neutron Suppression Regions (NSR) and Polar Hydrogen (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Orbital detection of neutrons has become the dominant remote sensing technique for detecting and inferring H concentrations and its spatial distribution beneath planetary surfaces [Lawrence et al, (2010) Icarus, 205, pp. 195-209, Mitrofanov et al (2007) Science 297(5578), 78-81]. Indications for the presence of localized and relatively high water content was provided by LRO and LCROSS. LEND identified Cabeus, as the most promising LCROSS impact site [Mitrofanov I. et al. (2010) Science, 330, 483], and instruments onboard LRO and LCROSS have measured signatures of water, H2 and other volatiles in the impact plume [Colaprete A. et al. (2010) Science, 339,463, Gladstone R. et al. (2010) Science, 330, 472].
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC.CPR.4449.2011 , 8th Annual Meeting and Geosciences World Community Exhibition (AOGS2011); Aug 08, 2011 - Aug 12, 2011; Taipei; Taiwan, Province of China
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  • 8
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    Topographically Induced Thermal Effects on Lunar Hydrogen Distributions: Correlated Observations from the LRO LEND and LOLA Instruments (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The question of whether water exists on the Moon's surface has long been an enigma to Lunar researchers. Largely, this was due to the thermally extreme lunar surface environment that would seem to preclude any long term maintenance, manufacture, transport or accumulation of hydrogen (H) volatiles over most of the lunar surface. As a result, for many years the cold permanent shadow regions (PSR) in the bottoms of craters near the lunar poles appeared to provide the basic conditions at least for maintenance of lunar hydrogen. Importantly, recent discoveries indicate that there is some hydrogen at the poles. However, the picture of the lunar hydrogen budget may be more complex than the PSR hypothesis has suggested. This evidence comes from observations by the Lunar Exploration Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter (LRO) that inclici1te 1) some H concentrations lie outside PSR and 2) though a few of the larger PSR's have high hydrogen, PSR does not appear to be an independent factor influencing the large-scale suppression of polar epithermals observed by LEND and the Lunar Prospector Neutron Spectrometer. In this research we investigate the possibility that the thermal contrast between pole-facing and equator facing-slopes is a factor influencing the surface distributions of lunar H. We perform this bulk correlated observation and study by developing a thermal proxy from slope data of the Lunar Orbiting Laser Altimeter (LOLA) digital elevation model (DEM) which is registered with the collimated LEND epithermal map. From the LOLA transforms we impose a thermal functional decomposition and systematic statistical analysis of the LEND epithermal map. Our hypothesis testing suggests in most high latitude bands studied〉 +/- 45 deg: Epithermal rates in pole-facing slopes are significantly lower than epithermal rates in equivalent equator-facing slopes. As a control study, we find that there is no statistically significant difference between equivalent east and west facing slopes. This finding suggests topographic modulation of insolation is a factor influencing the lunar H budget. Importantly, this result is consistent with observations in terrestrial, Martian research.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC.OVPR.5744.2011
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  • 9
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    Background and Lunar Neutron Populations Detected by LEND and Average Concentration of Near-Surface Hydrogen near the Moon's Poles (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Neutron flux measurements by the Lunar Exploration Neutron Detector (LEND) on the Lunar Reconnaissance Orbiter (LRO) enable quantifying hydrogen-bearing volatiles in the lunar surface from orbit. Accurately determining hydrogen abundance requires discriminating between the instrument background detection rate and the population of lunar-sourced neutrons that are sensitive to surficial hydrogen. We have investigated the detection rate for lunar and non-lunar (spacecraft-sourced) neutrons in LEND by modeling maps of measured count rate in three LEND detector systems using linear combinations of maps compiled from LEND detectors and from the Lunar Prospector Neutron Spectrometer. We find that 30% of the global-average 24.926 +/- 0.020 neutron counts per second (cps) detected by the LEND STN3 thermal-energy neutron sensor are lunar-sourced neutrons in the thermal energy range (E 〈 0.4 eV), 65% are lunar-sourced neutrons in the epithermal and fast energy range (E 〉 0.4 eV), and 5% are from spacecraft-sourced background signal. In the SETN epithermal neutron detector, 90% of the 10.622 +/- 0.002 neutron detections per second are consistent with a lunar source of epithermal and fast neutrons combined (E 〉 0.4 eV), with 3% due to lunar-sourced thermal neutron leakage into the detector (E 〈 0.4 eV), and background signal accounting for 7% of total detections. Background signal due to spacecraft-derived neutrons is substantial in the CSETN collimated detector system, accounting for 57% of the global average detection rate of 5.082 +/- 0.001 cps, greater than the 48% estimated from cruise-phase data. Lunar-sourced epithermal and fast neutrons account for 43% of detected neutrons, including neutrons in collimation as well as neutrons that penetrate the collimator wall to reach the detector. We estimate a lower limit of 17% of lunar-sourced neutrons detected by CSETN are epithermal neutrons in collimation (0.37 cps), with an upper limit estimate of 54 +/- 11% of lunar-sourced neutrons received in collimation, or 1.2 +/- 0.2 cps global average. The pole-to-equator contrast ratio in epithermal and high-energy epithermal neutron flux indicates that the average concentration of hydrogen in the polar regolith above 80deg north or south latitude is 105 ppmw (parts per million by weight), or 0.095 +/- 0.01 wt% water-equivalent hydrogen. Above 88deg north or south, the concentration increases to 140 ppmw, or 0.13 +/- 0.02 wt% water-equivalent hydrogen. The similar pattern of neutron flux suppression at both poles suggests that hydrogen concentration generally increases nearer the pole and is not closely associated with a specific feature such as Shackleton Crater at the lunar south pole that has no northern counterpart. Epithermal neutron flux decreases with increasing latitude outside the polar regions, consistent with surface hydration that increases with latitude if that hydration extends to 13-40 cm into the surface.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN50885 , Planetary and Space Science (ISSN 0032-0633); 162; 89-104
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  • 10
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    Estimation of Orbital Neutron Detector Spatial Resolution by Systematic Shifting of Differential Topographic Masks (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: We present a method and preliminary results related to determining the spatial resolution of orbital neutron detectors using epithermal maps and differential topographic masks. Our technique is similar to coded aperture imaging methods for optimizing photonic signals in telescopes [I]. In that approach photon masks with known spatial patterns in a telescope aperature are used to systematically restrict incoming photons which minimizes interference and enhances photon signal to noise. Three orbital neutron detector systems with different stated spatial resolutions are evaluated. The differing spatial resolutions arise due different orbital altitudes and the use of neutron collimation techniques. 1) The uncollimated Lunar Prospector Neutron Spectrometer (LPNS) system has spatial resolution of 45km FWHM from approx. 30km altitude mission phase [2]. The Lunar Rennaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND) with two detectors at 50km altitude evaluated here: 2) the collimated 10km FWHM spatial resolution detector CSETN and 3) LEND's collimated Sensor for Epithermal Neutrons (SETN). Thus providing two orbital altitudes to study factors of: uncollimated vs collimated and two average altitudes for their effect on fields-of-view.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC.CP.6361.2012 , 2012 Lunar and Planetary Science Conference; Mar 19, 2012 - Mar 24, 2012; The Woodlands, TX; United States
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