Evidence for geochemical terranes on Mercury: Global mapping of major elements with MESSENGER's X-Ray Spectrometer
TL;DR: In this article, the major-element composition of the surface of Mercury was mapped from orbital MESSENGER X-Ray Spectrometer measurements, and the results revealed highly variable compositions (e.g., Mg/Si and Al/Si range over 0.1 − 0.8 and 0.4, respectively).
About: This article is published in Earth and Planetary Science Letters.The article was published on 2015-04-15. It has received 165 citations till now. The article focuses on the topics: Partial melting.
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TL;DR: In this article, the MESSENGER spacecraft revealed that the planet's darkening agent is carbon and suggests that it originates from an ancient graphite-rich crust, and that it appeared darker globally than expected.
Abstract: Mercury appears darker globally than expected. Remote sensing evidence from the MESSENGER spacecraft indicates that the planet’s darkening agent is carbon and suggests that it originates from an ancient graphite-rich crust.
124 citations
TL;DR: In this article, the authors determined the range in density and compressibility of a possible Mercurian magma ocean and subsequent volcanism and showed that the only mineral to remain buoyant with respect to melts of the Mercurians mantle is graphite.
Abstract: The range in density and compressibility of Mercurian melt compositions was determined to better understand the products of a possible Mercurian magma ocean and subsequent volcanism. Our experiments indicate that the only mineral to remain buoyant with respect to melts of the Mercurian mantle is graphite; consequently, it is the only candidate mineral to have composed a primary floatation crust during a global magma ocean. This exotic result is further supported by Mercury's volatile-rich nature and inexplicably darkened surface. Additionally, our experiments illustrate that partial melts of the Mercurian mantle that compose the secondary crust were buoyant over the entire mantle depth and could have come from as deep as the core-mantle boundary. Furthermore, Mercury could have erupted higher percentages of its partial melts compared to other terrestrial planets because magmas would not have stalled during ascent due to gravitational forces. These findings stem from the FeO-poor composition and shallow depth of Mercury's mantle, which has resulted in both low-melt density and a very limited range in melt density responsible for Mercury's primary and secondary crusts. The enigmatically darkened, yet low-FeO surface, which is observed today, can be explained by secondary volcanism and impact processes that have since mixed the primary and secondary crustal materials.
109 citations
Cites background from "Evidence for geochemical terranes o..."
...Although there is some evidence that suggests this unit is not completely homogeneous [Peplowski et al., 2012a; Weider et al., 2015], the composition assessed from orbit is still broadly representative of Mercurian melts....
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TL;DR: In this article, an empirical parameterization was developed to predict sulfide saturation (SCSS) in Mercurian magmas as a function of oxygen fugacity ( f O 2 ), temperature, pressure and silicate melt composition.
103 citations
TL;DR: In this paper, a global multispectral map in eight visible to near-infrared colors, at an average pixel scale of 1 km, was acquired by the MESSENGER Dual Imaging System.
91 citations
INAF1, European Space Research and Technology Centre2, Braunschweig University of Technology3, Johns Hopkins University Applied Physics Laboratory4, Space Research Centre5, Goddard Space Flight Center6, Austrian Academy of Sciences7, Sternberg Astronomical Institute8, University of Pisa9, University of Colorado Boulder10, Princeton University11, Princeton Plasma Physics Laboratory12, Southwest Research Institute13, Swedish Institute of Space Physics14, University of California, San Diego15, Planetary Science Institute16, Imperial College London17, Aberystwyth University18, Russian Academy of Sciences19
TL;DR: The ESA-JAXA BepiColombo mission will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric dynamics at Mercury as well as their interactions with the solar wind, radiation, and interplanetary dust.
Abstract: The ESA-JAXA BepiColombo mission will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric dynamics at Mercury as well as their interactions with the solar wind, radiation, and interplanetary dust. Many scientific instruments onboard the two spacecraft will be completely, or partially devoted to study the near-space environment of Mercury as well as the complex processes that govern it. Many issues remain unsolved even after the MESSENGER mission that ended in 2015. The specific orbits of the two spacecraft, MPO and Mio, and the comprehensive scientific payload allow a wider range of scientific questions to be addressed than those that could be achieved by the individual instruments acting alone, or by previous missions. These joint observations are of key importance because many phenomena in Mercury’s environment are highly temporally and spatially variable. Examples of possible coordinated observations are described in this article, analysing the required geometrical conditions, pointing, resolutions and operation timing of different BepiColombo instruments sensors.
87 citations
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TL;DR: The CHIANTI database as mentioned in this paper is a set of atomic data and transition probabilities necessary to calculate the emission line spectrum of astrophysical plasmas, including atomic energy levels, atomic radiative data such as wavelengths, weighted oscillator strengths and A values, and electron collisional excitation rates.
Abstract: CHIANTI consists of a critically evaluated set of atomic data and transition probabilities necessary to calculate the emission line spectrum of astrophysical plasmas. The data consist of atomic energy levels, atomic radiative data such as wavelengths, weighted oscillator strengths and A values, and electron collisional excitation rates. A set of programs that use these data to calculate the spectrum in a desired wavelength range as a function of temperature and density is also provided. A suite of programs has been developed to carry out plasma diagnostics of astrophysical plasmas. The state-of-the-art contents of the CHIANTI database will be described and some of the most important results obtained from the use of the CHIANTI database will be reviewed.
2,116 citations
"Evidence for geochemical terranes o..." refers methods in this paper
...1a, together with their lines of best fit and equivalent high-resolution theoretical solar spectra (generated with the CHIANTI code; Dere et al., 1997) that are used as inputs for the XRF modeling....
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Book•
01 Jan 1993
TL;DR: Remote geochemical analysis offers a powerful tool to study the elemental and mineralogical composition of our planet from its interior through to its atmosphere and to explore our solar system as mentioned in this paper, which has become possible because of major advances in sensor technology.
Abstract: Remote geochemical analysis offers a powerful tool to study the elemental and mineralogical composition of our planet from its interior through to its atmosphere and to explore our solar system. Such studies have become possible because of major advances in sensor technology. Remote Geochemical Analysis fully covers both techniques and key applications. Chapters have been contributed by experts in their respective fields and describe a variety of remote sensing tools and their use in gaining an understanding of compositional properties. This book offers students as well as researchers a unique single source of information about the acquisition of compositional information using advanced sensors.
521 citations
"Evidence for geochemical terranes o..." refers methods in this paper
...A similar methodology was used for analysis of Apollo 15 and 16 lunar XRF data (e.g., Yin et al., 1993)....
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...We generated element-ratio maps using a methodology (Weider et al., 2014) that combines XRF analyses with variable spatial resolution; see Section 5....
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TL;DR: X-ray fluorescence spectra obtained by the MESSENGENGER spacecraft orbiting Mercury indicate that the planet's surface differs in composition from those of other terrestrial planets as discussed by the authors, and this observation, together with a low surface Fe abundance, supports the view that Mercury formed from highly reduced precursor materials, perhaps akin to enstatite chondrite meteorites or anhydrous cometary dust particles.
Abstract: X-ray fluorescence spectra obtained by the MESSENGER spacecraft orbiting Mercury indicate that the planet's surface differs in composition from those of other terrestrial planets Relatively high Mg/Si and low Al/Si and Ca/Si ratios rule out a lunarlike feldspar-rich crust The sulfur abundance is at least 10 times higher than that of the silicate portion of Earth or the Moon, and this observation, together with a low surface Fe abundance, supports the view that Mercury formed from highly reduced precursor materials, perhaps akin to enstatite chondrite meteorites or anhydrous cometary dust particles Low Fe and Ti abundances do not support the proposal that opaque oxides of these elements contribute substantially to Mercury's low and variable surface reflectance
396 citations
Carnegie Institution for Science1, Johns Hopkins University2, Goddard Space Flight Center3, University of Colorado Boulder4, University of Arizona5, Southwest Research Institute6, University of Michigan7, University of Maryland, College Park8, Brown University9, University of California, Santa Barbara10, Washington University in St. Louis11, Northwestern University12, Massachusetts Institute of Technology13
TL;DR: The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission has been designed to fly by and orbit Mercury to address several critical questions regarding the formation and evolution of the terrestrial planets as mentioned in this paper.
391 citations
Massachusetts Institute of Technology1, Southwest Research Institute2, Carnegie Institution for Science3, Case Western Reserve University4, Goddard Space Flight Center5, University of California, Santa Barbara6, University of California, Los Angeles7, Planetary Science Institute8, University of British Columbia9, Johns Hopkins University Applied Physics Laboratory10, University of Maryland, Baltimore County11, Brown University12, KinetX13
TL;DR: The results point to an interior structure that differs from those of the other terrestrial planets: the density of the planet's solid outer shell suggests the existence of a deep reservoir of high-density material, possibly an Fe-S layer.
Abstract: 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/MR2 = 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 Cm/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.
284 citations