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  • 1
    Publication Date: 2012-06-23
    Description: Shackleton crater is nearly coincident with the Moon's south pole. Its interior receives almost no direct sunlight and is a perennial cold trap, making Shackleton a promising candidate location in which to seek sequestered volatiles. However, previous orbital and Earth-based radar mapping and orbital optical imaging have yielded conflicting interpretations about the existence of volatiles. Here we present observations from the Lunar Orbiter Laser Altimeter on board the Lunar Reconnaissance Orbiter, revealing Shackleton to be an ancient, unusually well-preserved simple crater whose interior walls are fresher than its floor and rim. Shackleton floor deposits are nearly the same age as the rim, suggesting that little floor deposition has occurred since the crater formed more than three billion years ago. At a wavelength of 1,064 nanometres, the floor of Shackleton is brighter than the surrounding terrain and the interiors of nearby craters, but not as bright as the interior walls. The combined observations are explicable primarily by downslope movement of regolith on the walls exposing fresher underlying material. The relatively brighter crater floor is most simply explained by decreased space weathering due to shadowing, but a one-micrometre-thick layer containing about 20 per cent surficial ice is an alternative possibility.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zuber, Maria T -- Head, James W -- Smith, David E -- Neumann, Gregory A -- Mazarico, Erwan -- Torrence, Mark H -- Aharonson, Oded -- Tye, Alexander R -- Fassett, Caleb I -- Rosenburg, Margaret A -- Melosh, H Jay -- England -- Nature. 2012 Jun 20;486(7403):378-81. doi: 10.1038/nature11216.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. zuber@mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22722197" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2012-12-12
    Description: The earliest history of the Moon is poorly preserved in the surface geologic record due to the high flux of impactors, but aspects of that history may be preserved in subsurface structures. Application of gravity gradiometry to observations by the Gravity Recovery and Interior Laboratory (GRAIL) mission results in the identification of a population of linear gravity anomalies with lengths of hundreds of kilometers. Inversion of the gravity anomalies indicates elongated positive-density anomalies that are interpreted to be ancient vertical tabular intrusions or dikes formed by magmatism in combination with extension of the lithosphere. Crosscutting relationships support a pre-Nectarian to Nectarian age, preceding the end of the heavy bombardment of the Moon. The distribution, orientation, and dimensions of the intrusions indicate a globally isotropic extensional stress state arising from an increase in the Moon's radius by 0.6 to 4.9 kilometers early in lunar history, consistent with predictions of thermal models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Andrews-Hanna, Jeffrey C -- Asmar, Sami W -- Head, James W 3rd -- Kiefer, Walter S -- Konopliv, Alexander S -- Lemoine, Frank G -- Matsuyama, Isamu -- Mazarico, Erwan -- McGovern, Patrick J -- Melosh, H Jay -- Neumann, Gregory A -- Nimmo, Francis -- Phillips, Roger J -- Smith, David E -- Solomon, Sean C -- Taylor, G Jeffrey -- Wieczorek, Mark A -- Williams, James G -- Zuber, Maria T -- New York, N.Y. -- Science. 2013 Feb 8;339(6120):675-8. doi: 10.1126/science.1231753. Epub 2012 Dec 5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geophysics and Center for Space Resources, Colorado School of Mines, Golden, CO 80401, USA. jcahanna@mines.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23223393" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2013-07-05
    Description: The most heavily cratered terrains on Mercury have been estimated to be about 4 billion years (Gyr) old, but this was based on images of only about 45 per cent of the surface; even older regions could have existed in the unobserved portion. These terrains have a lower density of craters less than 100 km in diameter than does the Moon, an observation attributed to preferential resurfacing on Mercury. Here we report global crater statistics of Mercury's most heavily cratered terrains on the entire surface. Applying a recent model for early lunar crater chronology and an updated dynamical extrapolation to Mercury, we find that the oldest surfaces were emplaced just after the start of the Late Heavy Bombardment (LHB) about 4.0-4.1 Gyr ago. Mercury's global record of large impact basins, which has hitherto not been dated, yields a similar surface age. This agreement implies that resurfacing was global and was due to volcanism, as previously suggested. This activity ended during the tail of the LHB, within about 300-400 million years after the emplacement of the oldest terrains on Mercury. These findings suggest that persistent volcanism could have been aided by the surge of basin-scale impacts during this bombardment.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marchi, Simone -- Chapman, Clark R -- Fassett, Caleb I -- Head, James W -- Bottke, W F -- Strom, Robert G -- England -- Nature. 2013 Jul 4;499(7456):59-61. doi: 10.1038/nature12280.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉NASA Lunar Science Institute, Southwest Research Institute, Boulder, Colorado 80302, USA. marchi@boulder.swri.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23823793" target="_blank"〉PubMed〈/a〉
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    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2014-10-04
    Description: The Procellarum region is a broad area on the nearside of the Moon that is characterized by low elevations, thin crust, and high surface concentrations of the heat-producing elements uranium, thorium, and potassium. The region has been interpreted as an ancient impact basin approximately 3,200 kilometres in diameter, although supporting evidence at the surface would have been largely obscured as a result of the great antiquity and poor preservation of any diagnostic features. Here we use data from the Gravity Recovery and Interior Laboratory (GRAIL) mission to examine the subsurface structure of Procellarum. The Bouguer gravity anomalies and gravity gradients reveal a pattern of narrow linear anomalies that border Procellarum and are interpreted to be the frozen remnants of lava-filled rifts and the underlying feeder dykes that served as the magma plumbing system for much of the nearside mare volcanism. The discontinuous surface structures that were earlier interpreted as remnants of an impact basin rim are shown in GRAIL data to be a part of this continuous set of border structures in a quasi-rectangular pattern with angular intersections, contrary to the expected circular or elliptical shape of an impact basin. The spatial pattern of magmatic-tectonic structures bounding Procellarum is consistent with their formation in response to thermal stresses produced by the differential cooling of the province relative to its surroundings, coupled with magmatic activity driven by the greater-than-average heat flux in the region.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Andrews-Hanna, Jeffrey C -- Besserer, Jonathan -- Head, James W 3rd -- Howett, Carly J A -- Kiefer, Walter S -- Lucey, Paul J -- McGovern, Patrick J -- Melosh, H Jay -- Neumann, Gregory A -- Phillips, Roger J -- Schenk, Paul M -- Smith, David E -- Solomon, Sean C -- Zuber, Maria T -- England -- Nature. 2014 Oct 2;514(7520):68-71. doi: 10.1038/nature13697.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geophysics and Center for Space Resources, Colorado School of Mines, Golden, Colorado 80401, USA. ; Department of Earth and Planetary Sciences, University of California, Santa Cruz, California 95064, USA. ; Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island 02912, USA. ; Planetary Science Directorate, Southwest Research Institute, Boulder, Colorado 80302, USA. ; Lunar and Planetary Institute, Houston, Texas 77058, USA. ; Hawaii Institute of Geophysics and Planetology, University of Hawaii, Honolulu, Hawaii 96822, USA. ; Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, USA. ; Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA. ; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA. ; 1] Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington DC 20015, USA [2] Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25279919" target="_blank"〉PubMed〈/a〉
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    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2011-10-01
    Description: High-resolution images of Mercury's surface from orbit reveal that many bright deposits within impact craters exhibit fresh-appearing, irregular, shallow, rimless depressions. The depressions, or hollows, range from tens of meters to a few kilometers across, and many have high-reflectance interiors and halos. The host rocks, which are associated with crater central peaks, peak rings, floors, and walls, are interpreted to have been excavated from depth by the crater-forming process. The most likely formation mechanisms for the hollows involve recent loss of volatiles through some combination of sublimation, space weathering, outgassing, or pyroclastic volcanism. These features support the inference that Mercury's interior contains higher abundances of volatile materials than predicted by most scenarios for the formation of the solar system's innermost planet.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Blewett, David T -- Chabot, Nancy L -- Denevi, Brett W -- Ernst, Carolyn M -- Head, James W -- Izenberg, Noam R -- Murchie, Scott L -- Solomon, Sean C -- Nittler, Larry R -- McCoy, Timothy J -- Xiao, Zhiyong -- Baker, David M H -- Fassett, Caleb I -- Braden, Sarah E -- Oberst, Jurgen -- Scholten, Frank -- Preusker, Frank -- Hurwitz, Debra M -- New York, N.Y. -- Science. 2011 Sep 30;333(6051):1856-9. doi: 10.1126/science.1211681.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA. david.blewett@jhuapl.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21960626" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2012-03-23
    Description: Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zuber, Maria T -- Smith, David E -- Phillips, Roger J -- Solomon, Sean C -- Neumann, Gregory A -- Hauck, Steven A 2nd -- Peale, Stanton J -- Barnouin, Olivier S -- Head, James W -- Johnson, Catherine L -- Lemoine, Frank G -- Mazarico, Erwan -- Sun, Xiaoli -- Torrence, Mark H -- Freed, Andrew M -- Klimczak, Christian -- Margot, Jean-Luc -- Oberst, Jurgen -- Perry, Mark E -- McNutt, Ralph L Jr -- Balcerski, Jeffrey A -- Michel, Nathalie -- Talpe, Matthieu J -- Yang, Di -- New York, N.Y. -- Science. 2012 Apr 13;336(6078):217-20. doi: 10.1126/science.1218805. Epub 2012 Mar 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. zuber@mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22438510" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2011-10-01
    Description: MESSENGER observations from Mercury orbit reveal that a large contiguous expanse of smooth plains covers much of Mercury's high northern latitudes and occupies more than 6% of the planet's surface area. These plains are smooth, embay other landforms, are distinct in color, show several flow features, and partially or completely bury impact craters, the sizes of which indicate plains thicknesses of more than 1 kilometer and multiple phases of emplacement. These characteristics, as well as associated features, interpreted to have formed by thermal erosion, indicate emplacement in a flood-basalt style, consistent with x-ray spectrometric data indicating surface compositions intermediate between those of basalts and komatiites. The plains formed after the Caloris impact basin, confirming that volcanism was a globally extensive process in Mercury's post-heavy bombardment era.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Head, James W -- Chapman, Clark R -- Strom, Robert G -- Fassett, Caleb I -- Denevi, Brett W -- Blewett, David T -- Ernst, Carolyn M -- Watters, Thomas R -- Solomon, Sean C -- Murchie, Scott L -- Prockter, Louise M -- Chabot, Nancy L -- Gillis-Davis, Jeffrey J -- Whitten, Jennifer L -- Goudge, Timothy A -- Baker, David M H -- Hurwitz, Debra M -- Ostrach, Lillian R -- Xiao, Zhiyong -- Merline, William J -- Kerber, Laura -- Dickson, James L -- Oberst, Jurgen -- Byrne, Paul K -- Klimczak, Christian -- Nittler, Larry R -- New York, N.Y. -- Science. 2011 Sep 30;333(6051):1853-6. doi: 10.1126/science.1211997.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geological Sciences, Brown University, Providence, RI 02912, USA. james_head@brown.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21960625" target="_blank"〉PubMed〈/a〉
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  • 8
    Publication Date: 2012-03-23
    Description: Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR(2) = 0.353 +/- 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(m)/C = 0.452 +/- 0.035. A model for Mercury's radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smith, David E -- Zuber, Maria T -- Phillips, Roger J -- Solomon, Sean C -- Hauck, Steven A 2nd -- Lemoine, Frank G -- Mazarico, Erwan -- Neumann, Gregory A -- Peale, Stanton J -- Margot, Jean-Luc -- Johnson, Catherine L -- Torrence, Mark H -- Perry, Mark E -- Rowlands, David D -- Goossens, Sander -- Head, James W -- Taylor, Anthony H -- New York, N.Y. -- Science. 2012 Apr 13;336(6078):214-7. doi: 10.1126/science.1218809. Epub 2012 Mar 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22438509" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2015-05-09
    Description: Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury's crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury's history. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust inferred from MESSENGER elemental composition data.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnson, Catherine L -- Phillips, Roger J -- Purucker, Michael E -- Anderson, Brian J -- Byrne, Paul K -- Denevi, Brett W -- Feinberg, Joshua M -- Hauck, Steven A 2nd -- Head, James W 3rd -- Korth, Haje -- James, Peter B -- Mazarico, Erwan -- Neumann, Gregory A -- Philpott, Lydia C -- Siegler, Matthew A -- Tsyganenko, Nikolai A -- Solomon, Sean C -- New York, N.Y. -- Science. 2015 May 22;348(6237):892-5. doi: 10.1126/science.aaa8720. Epub 2015 May 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada. Planetary Science Institute, Tucson, AZ 85719, USA. cjohnson@eos.ubc.ca. ; Planetary Science Directorate, Southwest Research Institute, Boulder, CO 80302, USA. ; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. ; The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA. ; Lunar and Planetary Institute, Houston, TX 77058, USA. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA. ; Institute for Rock Magnetism, Department of Earth Sciences, University of Minnesota, Minneapolis, MN, 55455, USA. ; Department of Earth, Environmental, and Planetary Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA. ; Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA. ; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA. ; Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada. ; Planetary Science Institute, Tucson, AZ 85719, USA. Department of Earth Sciences, Southern Methodist University, Dallas, TX 75205, USA. ; Institute and Faculty of Physics, Saint Petersburg State University, Saint Petersburg, Russia. ; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25953822" target="_blank"〉PubMed〈/a〉
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  • 10
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Gillespie et al. concur with our interpretation that certain lobate equatorial and mid-latitude features on Mars are due to debris-covered glaciers formed largely during past periods of increased spin-axis obliquity, when climate regimes favoured snow and ice accumulation and glacial ...
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