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Lauretta DS, DellaGiustina DN, Bennett CA, Golish DR, Becker KJ, Balram-Knutson SS, Barnouin OS, Becker TL, Bottke WF, Boynton WV, Campins H, Clark BE, Connolly HC, Drouet d'Aubigny CY, Dworkin JP, Emery JP, Enos HL, Hamilton VE, Hergenrother CW, Howell ES, Izawa MRM, Kaplan HH, Nolan MC, Rizk B, Roper HL, Scheeres DJ, Smith PH, Walsh KJ, Wolner CWV. The unexpected surface of asteroid (101955) Bennu. Nature 2019; 568:55-60. [PMID: 30890786 PMCID: PMC6557581 DOI: 10.1038/s41586-019-1033-6] [Citation(s) in RCA: 268] [Impact Index Per Article: 53.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 02/15/2019] [Indexed: 11/09/2022]
Abstract
NASA'S Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer (OSIRIS-REx) spacecraft recently arrived at the near-Earth asteroid (101955) Bennu, a primitive body that represents the objects that may have brought prebiotic molecules and volatiles such as water to Earth1. Bennu is a low-albedo B-type asteroid2 that has been linked to organic-rich hydrated carbonaceous chondrites3. Such meteorites are altered by ejection from their parent body and contaminated by atmospheric entry and terrestrial microbes. Therefore, the primary mission objective is to return a sample of Bennu to Earth that is pristine-that is, not affected by these processes4. The OSIRIS-REx spacecraft carries a sophisticated suite of instruments to characterize Bennu's global properties, support the selection of a sampling site and document that site at a sub-centimetre scale5-11. Here we consider early OSIRIS-REx observations of Bennu to understand how the asteroid's properties compare to pre-encounter expectations and to assess the prospects for sample return. The bulk composition of Bennu appears to be hydrated and volatile-rich, as expected. However, in contrast to pre-encounter modelling of Bennu's thermal inertia12 and radar polarization ratios13-which indicated a generally smooth surface covered by centimetre-scale particles-resolved imaging reveals an unexpected surficial diversity. The albedo, texture, particle size and roughness are beyond the spacecraft design specifications. On the basis of our pre-encounter knowledge, we developed a sampling strategy to target 50-metre-diameter patches of loose regolith with grain sizes smaller than two centimetres4. We observe only a small number of apparently hazard-free regions, of the order of 5 to 20 metres in extent, the sampling of which poses a substantial challenge to mission success.
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Affiliation(s)
- D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
| | - D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C A Bennett
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D R Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K J Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - O S Barnouin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - T L Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - W F Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - W V Boynton
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H Campins
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - B E Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | - H C Connolly
- Department of Geology, Rowan University, Glassboro, NJ, USA
| | | | - J P Dworkin
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - J P Emery
- Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN, USA
| | - H L Enos
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - C W Hergenrother
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - E S Howell
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M R M Izawa
- Institute for Planetary Materials, Okayama University-Misasa, Misasa, Japan
| | - H H Kaplan
- Southwest Research Institute, Boulder, CO, USA
| | - M C Nolan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H L Roper
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D J Scheeres
- Smead Department of Aerospace Engineering, University of Colorado, Boulder, CO, USA
| | - P H Smith
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - C W V Wolner
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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2
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Barnouin OS, Daly MG, Palmer EE, Gaskell RW, Weirich JR, Johnson CL, Asad MMA, Roberts JH, Perry ME, Susorney HCM, Daly RT, Bierhaus EB, Seabrook JA, Espiritu RC, Nair AH, Nguyen L, Neumann GA, Ernst CM, Boynton WV, Nolan MC, Adam CD, Moreau MC, Risk B, D'Aubigny CD, Jawin ER, Walsh KJ, Michel P, Schwartz SR, Ballouz RL, Mazarico EM, Scheeres DJ, McMahon J, Bottke W, Sugita S, Hirata N, Hirata N, Watanabe S, Burke KN, DellaGuistina DN, Bennett CA, Lauretta DS. Shape of (101955) Bennu indicative of a rubble pile with internal stiffness. Nat Geosci 2019; 12:247-252. [PMID: 31080497 PMCID: PMC6505705 DOI: 10.1038/s41561-019-0330-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 02/15/2019] [Indexed: 05/18/2023]
Abstract
The shapes of asteroids reflect interplay between their interior properties and the processes responsible for their formation and evolution as they journey through the Solar System. Prior to the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) mission, Earth-based radar imaging gave an overview of (101955) Bennu's shape. Here, we construct a high-resolution shape model from OSIRIS-REx images. We find that Bennu's top-like shape, considerable macroporosity, and prominent surface boulders suggest that it is a rubble pile. High-standing, north-south ridges that extend from pole to pole, many long grooves, and surface mass wasting indicate some low levels of internal friction and/or cohesion. Our shape model indicates that, similar to other top-shaped asteroids, Bennu formed by reaccumulation and underwent past periods of fast spin leading to its current shape. Today, Bennu might follow a different evolutionary pathway, with interior stiffness permitting surface cracking and mass wasting.
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Affiliation(s)
- O S Barnouin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - M G Daly
- The Centre for Research in Earth and Space Science, York University, Toronto, Ontario, Canada
| | - E E Palmer
- Planetary Science Institute, Tucson, AZ, USA
| | - R W Gaskell
- Planetary Science Institute, Tucson, AZ, USA
| | - J R Weirich
- Planetary Science Institute, Tucson, AZ, USA
| | - C L Johnson
- Planetary Science Institute, Tucson, AZ, USA
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | - M M Al Asad
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | - J H Roberts
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - M E Perry
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - H C M Susorney
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | - R T Daly
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - E B Bierhaus
- Lockheed Martin Space Systems Company, Denver, CO, USA
| | | | - R C Espiritu
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - A H Nair
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - L Nguyen
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - G A Neumann
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - C M Ernst
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - W V Boynton
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M C Nolan
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C D Adam
- KinetX Aerospace, Inc. Simi Valley, CA, USA
| | - M C Moreau
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - B Risk
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - E R Jawin
- Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - P Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - S R Schwartz
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - R-L Ballouz
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - E M Mazarico
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - D J Scheeres
- Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - J McMahon
- Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - W Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - S Sugita
- University of Tokyo, Tokyo, Japan
| | - N Hirata
- Aizu University, Aizu-Wakamatsu, Japan
| | | | - S Watanabe
- Nagoya University, Nagoya, Japan
- Institute of Space and Astronautical Science, JAXA, Sagamihara, Japan
| | - K N Burke
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - C A Bennett
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D S Lauretta
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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Hamilton VE, Simon AA, Christensen PR, Reuter DC, Clark BE, Barucci MA, Bowles NE, Boynton WV, Brucato JR, Cloutis EA, Connolly HC, Hanna KLD, Emery JP, Enos HL, Fornasier S, Haberle CW, Hanna RD, Howell ES, Kaplan HH, Keller LP, Lantz C, Li JY, Lim LF, McCoy TJ, Merlin F, Nolan MC, Praet A, Rozitis B, Sandford SA, Schrader DL, Thomas CA, Zou XD, Lauretta DS. Evidence for widespread hydrated minerals on asteroid (101955) Bennu. Nat Astron 2019; 3:332-340. [PMID: 31360777 PMCID: PMC6662227 DOI: 10.1038/s41550-019-0722-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 02/12/2019] [Indexed: 05/18/2023]
Abstract
Early spectral data from the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission reveal evidence for abundant hydrated minerals on the surface of near-Earth asteroid (101955) Bennu in the form of a near-infrared absorption near 2.7 μm and thermal infrared spectral features that are most similar to those of aqueously altered CM carbonaceous chondrites. We observe these spectral features across the surface of Bennu, and there is no evidence of substantial rotational variability at the spatial scales of tens to hundreds of meters observed to date. In the visible and near-infrared (0.4 to 2.4 μm) Bennu's spectrum appears featureless and with a blue (negative) slope, confirming previous ground-based observations. Bennu may represent a class of objects that could have brought volatiles and organic chemistry to Earth.
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Affiliation(s)
- V. E. Hamilton
- Department of Space Studies, Southwest Research Institute, Boulder, CO, USA
| | - A. A. Simon
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - P. R. Christensen
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - D. C. Reuter
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - B. E. Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | | | - N. E. Bowles
- Department of Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford, UK
| | - W. V. Boynton
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - J. R. Brucato
- INAF-Astrophysical Observatory of Arcetri, Firenze, Italy
| | - E. A. Cloutis
- Department of Geography, University of Winnipeg, Winnipeg, Canada
| | - H. C. Connolly
- Department of Geology, Rowan University, Glassboro, NJ, USA
| | - K. L. Donaldson Hanna
- Department of Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford, UK
| | - J. P. Emery
- Department of Earth and Planetary Science, University of Tennessee, Knoxville, TN, USA
| | - H. L. Enos
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - C. W. Haberle
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - R. D. Hanna
- Jackson School of Geosciences, University of Texas, Austin, TX, USA
| | - E. S. Howell
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H. H. Kaplan
- Department of Space Studies, Southwest Research Institute, Boulder, CO, USA
| | - L. P. Keller
- ARES, NASA Johnson Space Center, Houston, TX USA
| | - C. Lantz
- Institut d’Astrophysique Spatiale, CNRS/Université Paris Sud, Orsay, France
| | - J.-Y. Li
- Planetary Science Institute, Tucson, AZ, USA
| | - L. F. Lim
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - T. J. McCoy
- Smithsonian Institution, National Museum of Natural History, Washington, D.C., USA
| | - F. Merlin
- LESIA, Observatoire de Paris, France
| | - M. C. Nolan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - A. Praet
- LESIA, Observatoire de Paris, France
| | - B. Rozitis
- Planetary and Space Sciences, The Open University, Milton Keynes, UK
| | | | - D. L. Schrader
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - C. A. Thomas
- Department of Physics and Astronomy, Northern Arizona University, Flagstaff, AZ, USA
| | - X.-D. Zou
- Planetary Science Institute, Tucson, AZ, USA
| | - D. S. Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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4
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Boynton WV, Droege GF, Mitrofanov IG, McClanahan TP, Sanin AB, Litvak ML, Schaffner M, Chin G, Evans LG, Garvin JB, Harshman K, Malakhov A, Milikh G, Sagdeev R, Starr R. High spatial resolution studies of epithermal neutron emission from the lunar poles: Constraints on hydrogen mobility. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011je003979] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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5
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Sanin AB, Mitrofanov IG, Litvak ML, 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 RD, Zuber MT. Testing lunar permanently shadowed regions for water ice: LEND results from LRO. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011je003971] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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6
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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] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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7
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Mitrofanov IG, Boynton WV, Litvak ML, Sanin AB, Starr RD. Response to Comment on “Hydrogen Mapping of the Lunar South Pole Using the LRO Neutron Detector Experiment LEND”. Science 2011; 334:1058-d. [DOI: 10.1126/science.1203483] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- I. G. Mitrofanov
- Institute for Space Research of Russian Academy of Science, 117997 Moscow, Russia
| | | | - M. L. Litvak
- Institute for Space Research of Russian Academy of Science, 117997 Moscow, Russia
| | - A. B. Sanin
- Institute for Space Research of Russian Academy of Science, 117997 Moscow, Russia
| | - R. D. Starr
- Catholic University, Washington, DC 20015, USA
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8
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Mitrofanov IG, Sanin AB, Boynton WV, Chin G, Garvin JB, Golovin D, Evans LG, Harshman K, Kozyrev AS, Litvak ML, Malakhov A, Mazarico E, McClanahan T, Milikh G, Mokrousov M, Nandikotkur G, Neumann GA, Nuzhdin I, Sagdeev R, Shevchenko V, Shvetsov V, Smith DE, Starr R, Tretyakov VI, Trombka J, Usikov D, Varenikov A, Vostrukhin A, Zuber MT. Hydrogen mapping of the lunar south pole using the LRO neutron detector experiment LEND. Science 2010; 330:483-6. [PMID: 20966247 DOI: 10.1126/science.1185696] [Citation(s) in RCA: 212] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Hydrogen has been inferred to occur in enhanced concentrations within permanently shadowed regions and, hence, the coldest areas of the lunar poles. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was designed to detect hydrogen-bearing volatiles directly. Neutron flux measurements of the Moon's south polar region from the Lunar Exploration Neutron Detector (LEND) on the Lunar Reconnaissance Orbiter (LRO) spacecraft were used to select the optimal impact site for LCROSS. LEND data show several regions where the epithermal neutron flux from the surface is suppressed, which is indicative of enhanced hydrogen content. These regions are not spatially coincident with permanently shadowed regions of the Moon. The LCROSS impact site inside the Cabeus crater demonstrates the highest hydrogen concentration in the lunar south polar region, corresponding to an estimated content of 0.5 to 4.0% water ice by weight, depending on the thickness of any overlying dry regolith layer. The distribution of hydrogen across the region is consistent with buried water ice from cometary impacts, hydrogen implantation from the solar wind, and/or other as yet unknown sources.
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Affiliation(s)
- I G Mitrofanov
- Institute for Space Research of the Russian Academy of Science, 117997 Moscow, Russia.
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9
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Kounaves SP, Hecht MH, Kapit J, Gospodinova K, DeFlores L, Quinn RC, Boynton WV, Clark BC, Catling DC, Hredzak P, Ming DW, Moore Q, Shusterman J, Stroble S, West SJ, Young SMM. Wet Chemistry experiments on the 2007 Phoenix Mars Scout Lander mission: Data analysis and results. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009je003424] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Boynton WV, Ming DW, Kounaves SP, Young SMM, Arvidson RE, Hecht MH, Hoffman J, Niles PB, Hamara DK, Quinn RC, Smith PH, Sutter B, Catling DC, Morris RV. Evidence for calcium carbonate at the Mars Phoenix landing site. Science 2009; 325:61-4. [PMID: 19574384 DOI: 10.1126/science.1172768] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Carbonates are generally products of aqueous processes and may hold important clues about the history of liquid water on the surface of Mars. Calcium carbonate (approximately 3 to 5 weight percent) has been identified in the soils around the Phoenix landing site by scanning calorimetry showing an endothermic transition beginning around 725 degrees C accompanied by evolution of carbon dioxide and by the ability of the soil to buffer pH against acid addition. Based on empirical kinetics, the amount of calcium carbonate is most consistent with formation in the past by the interaction of atmospheric carbon dioxide with liquid water films on particle surfaces.
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Affiliation(s)
- W V Boynton
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
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11
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Smith PH, Tamppari LK, Arvidson RE, Bass D, Blaney D, Boynton WV, Carswell A, Catling DC, Clark BC, Duck T, Dejong E, Fisher D, Goetz W, Gunnlaugsson HP, Hecht MH, Hipkin V, Hoffman J, Hviid SF, Keller HU, Kounaves SP, Lange CF, Lemmon MT, Madsen MB, Markiewicz WJ, Marshall J, McKay CP, Mellon MT, Ming DW, Morris RV, Pike WT, Renno N, Staufer U, Stoker C, Taylor P, Whiteway JA, Zent AP. H2O at the Phoenix landing site. Science 2009; 325:58-61. [PMID: 19574383 DOI: 10.1126/science.1172339] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Phoenix mission investigated patterned ground and weather in the northern arctic region of Mars for 5 months starting 25 May 2008 (solar longitude between 76.5 degrees and 148 degrees ). A shallow ice table was uncovered by the robotic arm in the center and edge of a nearby polygon at depths of 5 to 18 centimeters. In late summer, snowfall and frost blanketed the surface at night; H(2)O ice and vapor constantly interacted with the soil. The soil was alkaline (pH = 7.7) and contained CaCO(3), aqueous minerals, and salts up to several weight percent in the indurated surface soil. Their formation likely required the presence of water.
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Affiliation(s)
- P H Smith
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
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12
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Hecht MH, Kounaves SP, Quinn RC, West SJ, Young SMM, Ming DW, Catling DC, Clark BC, Boynton WV, Hoffman J, DeFlores LP, Gospodinova K, Kapit J, Smith PH. Detection of Perchlorate and the Soluble Chemistry of Martian Soil at the Phoenix Lander Site. Science 2009; 325:64-7. [DOI: 10.1126/science.1172466] [Citation(s) in RCA: 762] [Impact Index Per Article: 50.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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13
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Ming DW, Morris RV, Woida R, Sutter B, Lauer HV, Shinohara C, Golden DC, Boynton WV, Arvidson RE, Stewart RL, Tamppari LK, Gross M, Smith P. Mars 2007 Phoenix Scout mission Organic Free Blank: Method to distinguish Mars organics from terrestrial organics. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007je003061] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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Litvak ML, Mitrofanov IG, Barmakov YN, Behar A, Bitulev A, Bobrovnitsky Y, Bogolubov EP, Boynton WV, Bragin SI, Churin S, Grebennikov AS, Konovalov A, Kozyrev AS, Kurdumov IG, Krylov A, Kuznetsov YP, Malakhov AV, Mokrousov MI, Ryzhkov VI, Sanin AB, Shvetsov VN, Smirnov GA, Sholeninov S, Timoshenko GN, Tomilina TM, Tuvakin DV, Tretyakov VI, Troshin VS, Uvarov VN, Varenikov A, Vostrukhin A. The Dynamic Albedo of Neutrons (DAN) experiment for NASA's 2009 Mars Science Laboratory. Astrobiology 2008; 8:605-612. [PMID: 18598140 DOI: 10.1089/ast.2007.0157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We present a summary of the physical principles and design of the Dynamic Albedo of Neutrons (DAN) instrument onboard NASA's 2009 Mars Science Laboratory (MSL) mission. The DAN instrument will use the method of neutron-neutron activation analysis in a space application to study the abundance and depth distribution of water in the martian subsurface along the path of the MSL rover.
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Affiliation(s)
- M L Litvak
- Space Research Institute, Moscow, Russia.
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Boynton WV, Taylor GJ, Evans LG, Reedy RC, Starr R, Janes DM, Kerry KE, Drake DM, Kim KJ, Williams RMS, Crombie MK, Dohm JM, Baker V, Metzger AE, Karunatillake S, Keller JM, Newsom HE, Arnold JR, Brückner J, Englert PAJ, Gasnault O, Sprague AL, Mitrofanov I, Squyres SW, Trombka JI, d'Uston L, Wänke H, Hamara DK. Concentration of H, Si, Cl, K, Fe, and Th in the low- and mid-latitude regions of Mars. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2007je002887] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Keller JM, Boynton WV, Karunatillake S, Baker VR, Dohm JM, Evans LG, Finch MJ, Hahn BC, Hamara DK, Janes DM, Kerry KE, Newsom HE, Reedy RC, Sprague AL, Squyres SW, Starr RD, Taylor GJ, Williams RMS. Equatorial and midlatitude distribution of chlorine measured by Mars Odyssey GRS. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2006je002679] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Taylor GJ, Stopar JD, Boynton WV, Karunatillake S, Keller JM, Brückner J, Wänke H, Dreibus G, Kerry KE, Reedy RC, Evans LG, Starr RD, Martel LMV, Squyres SW, Gasnault O, Maurice S, d'Uston C, Englert P, Dohm JM, Baker VR, Hamara D, Janes D, Sprague AL, Kim KJ, Drake DM, McLennan SM, Hahn BC. Variations in K/Th on Mars. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2006je002676] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Sprague AL, Boynton WV, Kerry KE, Janes DM, Hunten DM, Kim KJ, Reedy RC, Metzger AE. Mars' South Polar Ar Enhancement: A Tracer for South Polar Seasonal Meridional Mixing. Science 2004; 306:1364-7. [PMID: 15472041 DOI: 10.1126/science.1098496] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The gamma ray spectrometer on the Mars Odyssey spacecraft measured an enhancement of atmospheric argon over southern high latitudes during autumn followed by dissipation during winter and spring. Argon does not freeze at temperatures normal for southern winter (approximately 145 kelvin) and is left in the atmosphere, enriched relative to carbon dioxide (CO2), as the southern seasonal cap of CO2 frost accumulates. Calculations of seasonal transport of argon into and out of southern high latitudes point to meridional (north-south) mixing throughout southern winter and spring.
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Affiliation(s)
- A L Sprague
- Lunar and Planetary Laboratory, 1629 East University Boulevard, University of Arizona, Tucson, AZ 85721-0092, USA.
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Mitrofanov IG, Zuber MT, Litvak ML, Boynton WV, Smith DE, Drake D, Hamara D, Kozyrev AS, Sanin AB, Shinohara C, Saunders RS, Tretyakov V. CO2 snow depth and subsurface water-ice abundance in the northern hemisphere of Mars. Science 2003; 300:2081-4. [PMID: 12829779 DOI: 10.1126/science.1084350] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Observations of seasonal variations of neutron flux from the high-energy neutron detector (HEND) on Mars Odyssey combined with direct measurements of the thickness of condensed carbon dioxide by the Mars Orbiter Laser Altimeter (MOLA) on Mars Global Surveyor show a latitudinal dependence of northern winter deposition of carbon dioxide. The observations are also consistent with a shallow substrate consisting of a layer with water ice overlain by a layer of drier soil. The lower ice-rich layer contains between 50 and 75 weight % water, indicating that the shallow subsurface at northern polar latitudes on Mars is even more water rich than that in the south.
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Affiliation(s)
- I G Mitrofanov
- Space Research Institute, Russian Academy of Sciences, Moscow, 117997, Russia.
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Boynton WV, Feldman WC, Squyres SW, Prettyman TH, Bruckner J, Evans LG, Reedy RC, Starr R, Arnold JR, Drake DM, Englert PAJ, Metzger AE, Mitrofanov I, Trombka JI, D'Uston C, Wanke H, Gasnault O, Hamara DK, Janes DM, Marcialis RL, Maurice S, Mikheeva I, Taylor GJ, Tokar R, Shinohara C. Distribution of hydrogen in the near surface of Mars: evidence for subsurface ice deposits. Science 2002; 297:81-5. [PMID: 12040090 DOI: 10.1126/science.1073722] [Citation(s) in RCA: 753] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Using the Gamma-Ray Spectrometer on the Mars Odyssey, we have identified two regions near the poles that are enriched in hydrogen. The data indicate the presence of a subsurface layer enriched in hydrogen overlain by a hydrogen-poor layer. The thickness of the upper layer decreases with decreasing distance to the pole, ranging from a column density of about 150 grams per square centimeter at -42 degrees latitude to about 40 grams per square centimeter at -77 degrees. The hydrogen-rich regions correlate with regions of predicted ice stability. We suggest that the host of the hydrogen in the subsurface layer is ice, which constitutes 35 +/- 15% of the layer by weight.
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Affiliation(s)
- W V Boynton
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
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Feldman WC, Boynton WV, Tokar RL, Prettyman TH, Gasnault O, Squyres SW, Elphic RC, Lawrence DJ, Lawson SL, Maurice S, McKinney GW, Moore KR, Reedy RC. Global distribution of neutrons from Mars: results from Mars odyssey. Science 2002; 297:75-8. [PMID: 12040088 DOI: 10.1126/science.1073541] [Citation(s) in RCA: 395] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Global distributions of thermal, epithermal, and fast neutron fluxes have been mapped during late southern summer/northern winter using the Mars Odyssey Neutron Spectrometer. These fluxes are selectively sensitive to the vertical and lateral spatial distributions of H and CO2 in the uppermost meter of the martian surface. Poleward of +/-60 degrees latitude is terrain rich in hydrogen, probably H2O ice buried beneath tens of centimeter-thick hydrogen-poor soil. The central portion of the north polar cap is covered by a thick CO2 layer, as is the residual south polar cap. Portions of the low to middle latitudes indicate subsurface deposits of chemically and/or physically bound H2O and/or OH.
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Affiliation(s)
- W C Feldman
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
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Trombka JI, Squyres SW, Bruckner J, Boynton WV, Reedy RC, McCoy TJ, Gorenstein P, Evans LG, Arnold JR, Starr RD, Nittler LR, Murphy ME, Mikheeva I, McNutt RL, McClanahan TP, McCartney E, Goldsten JO, Gold RE, Floyd SR, Clark PE, Burbine TH, Bhangoo JS, Bailey SH, Petaev M. The elemental composition of asteroid 433 eros: results of the NEAR-shoemaker X-ray spectrometer. Science 2000; 289:2101-5. [PMID: 11000107 DOI: 10.1126/science.289.5487.2101] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We report major element composition ratios for regions of the asteroid 433 Eros imaged during two solar flares and quiet sun conditions during the period of May to July 2000. Low aluminum abundances for all regions argue against global differentiation of Eros. Magnesium/silicon, aluminum/silicon, calcium/silicon, and iron/silicon ratios are best interpreted as a relatively primitive, chondritic composition. Marked depletions in sulfur and possible aluminum and calcium depletions, relative to ordinary chondrites, may represent signatures of limited partial melting or impact volatilization.
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Affiliation(s)
- JI Trombka
- Goddard Space Flight Center, Code 691, Greenbelt, MD 20771, USA. Space Sciences Building, Cornell University, Ithaca, NY 14853, USA. Max-Planck-Institut fur Chemie, Postfach 3060, D-55020 Mainz, Germany. Department of Planetary Science, Spac
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Trombka JI, Floyd SR, Boynton WV, Bailey S, Brückner J, Squyres SW, Evans LG, Clark PE, Starr R, Fiore E, Gold R, Goldsten J, McNutt R. Compositional mapping with the NEAR X ray/gamma ray spectrometer. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/97je00270] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Gleason JD, Kring DA, Hill DH, Boynton WV. Petrography and bulk chemistry of Martian orthopyroxenite ALH84001: implications for the origin of secondary carbonates. Geochim Cosmochim Acta 1997; 61:3503-3512. [PMID: 11540477 DOI: 10.1016/s0016-7037(97)00173-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
New petrologic and bulk geochemical data for the SNC-related (Martian) meteorite ALH84001 suggest a relatively simple igneous history overprinted by complex shock and hydrothermal processes. ALH84001 is an igneous orthopyroxene cumulate containing penetrative shock deformation textures and a few percent secondary extraterrestrial carbonates. Rare earth element (REE) patterns for several splits of the meteorite reveal substantial heterogeneity in REE abundances and significant fractionation of the REEs between crushed and uncrushed domains within the meteorite. Complex zoning in carbonates indicates nonequilibrium processes were involved in their formation, suggesting that CO2-rich fluids of variable composition infiltrated the rock while on Mars. We interpret petrographic textures to be consistent with an inorganic origin for the carbonate involving dissolution-replacement reactions between CO2-charged fluids and feldspathic glass in the meteorite. Carbonate formation clearly postdated processes that last redistributed the REE in the meteorite.
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Affiliation(s)
- J D Gleason
- Lunar and Planetary Laboratory, University of Arizona, Tucson 85721, USA
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Boynton WV, D'Uston LC, Young DT, Lunine JI, Waite JH, Bailey SH, Berthelier JJ, Bertaux JL, Borrel V, Burke MF, Cohen BA, McComas DH, Nordholt JE, Evans LG, Trombka JI. The determination of ice composition with instruments on cometary landers. Acta Astronaut 1997; 40:663-674. [PMID: 11540784 DOI: 10.1016/s0094-5765(97)00005-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The determination of the composition of materials that make up comets is essential in trying to understand the origin of these primitive objects. The ices especially could be made in several different astrophysical settings including the solar nebula, protosatellite nebulae of the giant planets, and giant molecular clouds that predate the formation of the solar system. Each of these environments makes different ices with different composition. In order to understand the origin of comets, one needs to determine the composition of each of the ice phases. For example, it is of interest to know that comets contain carbon monoxide, CO, but it is much more important to know how much of it is a pure solid phase, is trapped in clathrate hydrates, or is adsorbed on amorphous water ice. In addition, knowledge of the isotopic composition of the constituents will help determine the process that formed the compounds. Finally, it is important to understand the bulk elemental composition of the nucleus. When these data are compared with solar abundances, they put strong constraints on the macro-scale processes that formed the comet. A differential scanning calorimeter (DSC) and an evolved gas analyzer (EGA) will make the necessary association between molecular constituents and their host phases. This combination of instruments takes a small (tens of mg) sample of the comet and slowly heats it in a sealed oven. As the temperature is raised, the DSC precisely measures the heat required, and delivers the gases to the EGA. Changes in the heat required to raise the temperature at a controlled rate are used to identify phase transitions, e.g., crystallization of amorphous ice or melting of hexagonal ice, and the EGA correlates the gases released with the phase transition. The EGA consists of two mass spectrometers run in tandem. The first mass spectrometer is a magnetic-sector ion-momentum analyzer (MAG), and the second is an electrostatic time-of-flight analyzer (TOF). The TOF acts as a detector for the MAG and serves to resolve ambiguities between fragments of similar mass such as CO and N2. Because most of the compounds of interest for the volatile ices are simple, a gas chromatograph is not needed and thus more integration time is available to determine isotopic ratios. A gamma-ray spectrometer (GRS) will determine the elemental abundances of the bulk cometary material by determining the flux of gamma rays produced from the interaction of the cometary material with cosmic ray produced neutrons. Because the gamma rays can penetrate a distance of several tens of centimeters a large volume of material is analyzed. The measured composition is, therefore, much more likely to be representative of the bulk comet than a very small sample that might have lost some of its volatiles. Making these measurements on a lander offers substantial advantages over trying to address similar objectives from an orbiter. For example, an orbiter instrument can determine the presence and isotopic composition of CO in the cometary coma, but only a lander can determine the phase(s) in which the CO is located and separately determine the isotopic composition of each reservoir of CO. The bulk composition of the nucleus might be constrained from separate orbiter analyses of dust and gas in the coma, but the result will be very model dependent, as the ratio of gas to dust in the comet will vary and will not necessarily be equal to the bulk value.
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Boynton WV, Trombka JI, Feldman WC, Arnold JR, Englert PAJ, Metzger AE, Reedy RC, Squyres SW, Wänke H, Bailey SH, Brückner J, Callas JL, Drake DM, Duke P, Evans LG, Haines EL, McCloskey FC, Mills H, Shinohara C, Starr R. Science applications of the Mars Observer gamma ray spectrometer. ACTA ACUST UNITED AC 1992. [DOI: 10.1029/92je00538] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Trace element, isotopic, and mineralogic studies indicate that the proposed impact at the Cretaceous-Tertiary (K-T) boundary occurred in an ocean basin, although a minor component of continental material is required. The size and abundance of shocked minerals and the restricted geographic occurrence of the ejecta layer and impact-wave deposits suggest an impact between the Americas. Coarse boundary sediments at sites 151 and 153 in the Colombian Basin and 5- to 450-meter-thick boundary sediments in Cuba may be deposits of a giant wave produced by a nearby oceanic impact. On the southern peninsula of Haiti, a approximately 50-centimeter-thick ejecta layer occurs at the K-T boundary. This ejecta layer is approximately 25 times as thick as that at any known K-T site and suggests an impact site within approximately 1000 kilometers. Seismic reflection profiles suggest that a buried approximately 300-km-diameter candidate structure occurs in the Colombian Basin.
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Abstract
The abundance of samarium-152 in the Santa Clara iron meteorite is found to be 108 x 10(7) atoms per gram. This quantity, if attributed to fission of a superheavy element with atomic number 107 to 109, limits the amount of superheavy elements in the early solar system to 1.7 x 10(-5) times the abundance of uranium-238. For element 110, the limit is 3.4 x 10(-5).
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Abstract
The composition and morphology of magnetite in CI carbonaceous meteorites appear incompatible with a nebular origin. Mineralization on the meteorite parent body is a more plausible mode of formation. The iodine-xenon age of this material therefore dates an episode of secondary mineralization on a planetesimal rather than the epoch of condensation in the primitive solar nebula.
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