1
|
Wilson JK, Spence HE, Schwadron NA, Case AW, Looper MD, Jordan AP, de Wet W, Kasper J. Precise Detections of Solar Particle Events and a New View of the Moon. GEOPHYSICAL RESEARCH LETTERS 2020; 47:e2019GL085522. [PMID: 33688109 PMCID: PMC7939032 DOI: 10.1029/2019gl085522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/18/2019] [Indexed: 06/12/2023]
Abstract
We have invented a new method for detecting solar particle events using data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Using a simple function of the total particle detection rates from four of CRaTER's six detectors, we can precisely identify solar energetic particle event periods in the CRaTER data archive. During solar-quiet periods we map the distribution of a mare-associated mixture of elements in the lunar regolith using this new method. The new map of the moon probably reflects an as-yet unknown combination of lunar albedo protons, neutrons, and gamma rays, and most closely resembles Lunar Prospector maps of gamma rays characteristic of thorium and iron. This result will lead to multiple follow-up studies of lunar albedo particles and may also contribute to the study of diurnally-varying hydrogenation of the lunar regolith.
Collapse
Affiliation(s)
- Jody K Wilson
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA
- Solar System Exploration Research Virtual Institute, NASA Ames Research Center, Moffet Field, California, USA
| | - Harlan E Spence
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA
- Solar System Exploration Research Virtual Institute, NASA Ames Research Center, Moffet Field, California, USA
| | - Nathan A Schwadron
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA
- Solar System Exploration Research Virtual Institute, NASA Ames Research Center, Moffet Field, California, USA
| | - Anthony W Case
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA
| | - Mark D Looper
- The Aerospace Corporation, El Segundo, California, USA
| | - Andrew P Jordan
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA
- Solar System Exploration Research Virtual Institute, NASA Ames Research Center, Moffet Field, California, USA
| | - Wouter de Wet
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA
| | - Justin Kasper
- Michigan Institute for Research in Astrophysics, University of Michigan, Ann Arbor, Michigan, USA
| |
Collapse
|
2
|
Lawrence DJ, Peplowski PN, Prettyman TH, Feldman WC, Bazell D, Mittlefehldt DW, Reedy RC, Yamashita N. Constraints on Vesta's elemental composition: Fast neutron measurements by Dawn's gamma ray and neutron detector. METEORITICS & PLANETARY SCIENCE 2013; 48:2271-2288. [PMID: 26074718 PMCID: PMC4461122 DOI: 10.1111/maps.12187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 07/11/2013] [Indexed: 06/04/2023]
Abstract
Surface composition information from Vesta is reported using fast neutron data collected by the gamma ray and neutron detector on the Dawn spacecraft. After correcting for variations due to hydrogen, fast neutrons show a compositional dynamic range and spatial variability that is consistent with variations in average atomic mass from howardite, eucrite, and diogenite (HED) meteorites. These data provide additional compositional evidence that Vesta is the parent body to HED meteorites. A subset of fast neutron data having lower statistical precision show spatial variations that are consistent with a 400 ppm variability in hydrogen concentrations across Vesta and supports the idea that Vesta's hydrogen is due to long-term delivery of carbonaceous chondrite material.
Collapse
Affiliation(s)
- David J Lawrence
- The Johns Hopkins University Applied Physics LaboratoryLaurel, Maryland, USA
| | - Patrick N Peplowski
- The Johns Hopkins University Applied Physics LaboratoryLaurel, Maryland, USA
| | | | | | - David Bazell
- The Johns Hopkins University Applied Physics LaboratoryLaurel, Maryland, USA
| | | | | | | |
Collapse
|
3
|
Lawrence DJ, Feldman WC, Goldsten JO, Maurice S, Peplowski PN, Anderson BJ, Bazell D, McNutt RL, Nittler LR, Prettyman TH, Rodgers DJ, Solomon SC, Weider SZ. Evidence for water ice near Mercury's north pole from MESSENGER Neutron Spectrometer measurements. Science 2012. [PMID: 23196909 DOI: 10.1126/science.1229953] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Measurements by the Neutron Spectrometer on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft show decreases in the flux of epithermal and fast neutrons from Mercury's north polar region that are consistent with the presence of water ice in permanently shadowed regions. The neutron data indicate that Mercury's radar-bright polar deposits contain, on average, a hydrogen-rich layer more than tens of centimeters thick beneath a surficial layer 10 to 30 cm thick that is less rich in hydrogen. Combined neutron and radar data are best matched if the buried layer consists of nearly pure water ice. The upper layer contains less than 25 weight % water-equivalent hydrogen. The total mass of water at Mercury's poles is inferred to be 2 × 10(16) to 10(18) grams and is consistent with delivery by comets or volatile-rich asteroids.
Collapse
Affiliation(s)
- David J Lawrence
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Litvak ML, Mitrofanov IG, Sanin A, Malakhov A, Boynton WV, Chin G, Droege G, Evans LG, Garvin J, Golovin DV, Harshman K, McClanahan TP, Mokrousov MI, Mazarico E, Milikh G, Neumann G, Sagdeev R, Smith DE, Starr R, Zuber MT. Global maps of lunar neutron fluxes from the LEND instrument. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011je003949] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
5
|
Maurice S, Feldman W, Diez B, Gasnault O, Lawrence DJ, Pathare A, Prettyman T. Mars Odyssey neutron data: 1. Data processing and models of water-equivalent-hydrogen distribution. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011je003810] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
6
|
Lawrence DJ, Elphic RC, Feldman WC, Funsten HO, Prettyman TH. Performance of orbital neutron instruments for spatially resolved hydrogen measurements of airless planetary bodies. ASTROBIOLOGY 2010; 10:183-200. [PMID: 20298147 PMCID: PMC2956572 DOI: 10.1089/ast.2009.0401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 12/28/2009] [Indexed: 05/29/2023]
Abstract
Orbital neutron spectroscopy has become a standard technique for measuring planetary surface compositions from orbit. While this technique has led to important discoveries, such as the deposits of hydrogen at the Moon and Mars, a limitation is its poor spatial resolution. For omni-directional neutron sensors, spatial resolutions are 1-1.5 times the spacecraft's altitude above the planetary surface (or 40-600 km for typical orbital altitudes). Neutron sensors with enhanced spatial resolution have been proposed, and one with a collimated field of view is scheduled to fly on a mission to measure lunar polar hydrogen. No quantitative studies or analyses have been published that evaluate in detail the detection and sensitivity limits of spatially resolved neutron measurements. Here, we describe two complementary techniques for evaluating the hydrogen sensitivity of spatially resolved neutron sensors: an analytic, closed-form expression that has been validated with Lunar Prospector neutron data, and a three-dimensional modeling technique. The analytic technique, called the Spatially resolved Neutron Analytic Sensitivity Approximation (SNASA), provides a straightforward method to evaluate spatially resolved neutron data from existing instruments as well as to plan for future mission scenarios. We conclude that the existing detector--the Lunar Exploration Neutron Detector (LEND)--scheduled to launch on the Lunar Reconnaissance Orbiter will have hydrogen sensitivities that are over an order of magnitude poorer than previously estimated. We further conclude that a sensor with a geometric factor of approximately 100 cm(2) Sr (compared to the LEND geometric factor of approximately 10.9 cm(2) Sr) could make substantially improved measurements of the lunar polar hydrogen spatial distribution.
Collapse
Affiliation(s)
- David J Lawrence
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA.
| | | | | | | | | |
Collapse
|
7
|
Prettyman TH, Hagerty JJ, Elphic RC, Feldman WC, Lawrence DJ, McKinney GW, Vaniman DT. Elemental composition of the lunar surface: Analysis of gamma ray spectroscopy data from Lunar Prospector. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005je002656] [Citation(s) in RCA: 283] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - J. J. Hagerty
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - R. C. Elphic
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - W. C. Feldman
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - D. J. Lawrence
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - G. W. McKinney
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - D. T. Vaniman
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| |
Collapse
|
8
|
Lawrence DJ, Feldman WC, Elphic RC, Hagerty JJ, Maurice S, McKinney GW, Prettyman TH. Improved modeling of Lunar Prospector neutron spectrometer data: Implications for hydrogen deposits at the lunar poles. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005je002637] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
9
|
|
10
|
|
11
|
Prettyman TH. Composition and structure of the Martian surface at high southern latitudes from neutron spectroscopy. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003je002139] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
12
|
Lawrence DJ. Gamma-ray measurements from Lunar Prospector: Time series data reduction for the Gamma-Ray Spectrometer. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003je002206] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
13
|
|
14
|
Chevrel SD, Pinet PC, Daydou Y, Maurice S, Lawrence DJ, Feldman WC, Lucey PG. Integration of the Clementine UV-VIS spectral reflectance data and the Lunar Prospector gamma-ray spectrometer data: A global-scale multielement analysis of the lunar surface using iron, titanium, and thorium abundances. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2000je001419] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- S. D. Chevrel
- Groupe de Recherches de Géodésie Spatiale; Observatoire Midi-Pyrénées; Toulouse France
| | - P. C. Pinet
- Groupe de Recherches de Géodésie Spatiale; Observatoire Midi-Pyrénées; Toulouse France
| | - Y. Daydou
- Groupe de Recherches de Géodésie Spatiale; Observatoire Midi-Pyrénées; Toulouse France
| | - S. Maurice
- Observatoire Midi-Pyrénées; Toulouse France
| | - D. J. Lawrence
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - W. C. Feldman
- Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - P. G. Lucey
- Hawaii Institute of Geophysics and Planetology; University of Hawaii; Honolulu Hawaii USA
| |
Collapse
|
15
|
Lawrence DJ, Feldman WC, Elphic RC, Little RC, Prettyman TH, Maurice S, Lucey PG, Binder AB. Iron abundances on the lunar surface as measured by the Lunar Prospector gamma-ray and neutron spectrometers. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001je001530] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- D. J. Lawrence
- Space and Atmospheric Sciences; Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - W. C. Feldman
- Space and Atmospheric Sciences; Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - R. C. Elphic
- Space and Atmospheric Sciences; Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - R. C. Little
- Diagnostic Applications, Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - T. H. Prettyman
- Space and Atmospheric Sciences; Los Alamos National Laboratory; Los Alamos New Mexico USA
| | - S. Maurice
- Observatoire Midi-Pyrénées; Toulouse France
| | - P. G. Lucey
- Hawai'i Institute of Geophysics and Planetology; University of Hawaii; Honolulu Hawaii USA
| | | |
Collapse
|
16
|
Feldman WC, Maurice S, Lawrence DJ, Little RC, Lawson SL, Gasnault O, Wiens RC, Barraclough BL, Elphic RC, Prettyman TH, Steinberg JT, Binder AB. Evidence for water ice near the lunar poles. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000je001444] [Citation(s) in RCA: 229] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
17
|
Feldman WC, Lawrence DJ, Elphic RC, Vaniman DT, Thomsen DR, Barraclough BL, Maurice S, Binder AB. Chemical information content of lunar thermal and epithermal neutrons. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999je001183] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
18
|
Elphic RC, Lawrence DJ, Feldman WC, Barraclough BL, Maurice S, Binder AB, Lucey PG. Lunar rare earth element distribution and ramifications for FeO and TiO2: Lunar Prospector neutron spectrometer observations. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999je001176] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|