Mercury's Weather-Beaten Surface: Understanding Mercury in the Context of Lunar and Asteroidal Space Weathering Studies

被引：128

作者：

Domingue, Deborah L. ^{[1
]}

Chapman, Clark R. ^{[2
]}

Killen, Rosemary M. ^{[3
]}

Zurbuchen, Thomas H. ^{[4
]}

Gilbert, Jason A. ^{[4
]}

Sarantos, Menelaos ^{[5
]}

Benna, Mehdi ^{[3
]}

Slavin, James A. ^{[4
]}

Schriver, David ^{[6
]}

Travnicek, Pavel M. ^{[7
]}

Orlando, Thomas M. ^{[8
,9
]}

Sprague, Ann L. ^{[10
]}

Blewett, David T. ^{[11
]}

Gillis-Davis, Jeffrey J. ^{[12
]}

Feldman, William C. ^{[1
]}

Lawrence, David J. ^{[11
]}

Ho, George C. ^{[11
]}

Ebel, Denton S. ^{[13
]}

Nittler, Larry R. ^{[14
]}

Vilas, Faith ^{[1
]}

Pieters, Carle M. ^{[15
]}

Solomon, Sean C. ^{[14
,16
]}

Johnson, Catherine L. ^{[1
,17
]}

Winslow, Reka M. ^{[17
]}

Helbert, Joern ^{[18
]}

Peplowski, Patrick N. ^{[11
]}

Weider, Shoshana Z. ^{[14
]}

Mouawad, Nelly ^{[19
]}

Izenberg, Noam R. ^{[11
]}

McClintock, William E. ^{[20
]}

机构：

[1] Planetary Sci Inst, Tucson, AZ 85719 USA

[2] Southwest Res Inst, Boulder, CO 80302 USA

[3] NASA, Goddard Space Flight Ctr, Solar Syst Explorat Div, Greenbelt, MD 20771 USA

[4] Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA

[5] NASA, Goddard Space Flight Ctr, Heliophys Sci Div, Greenbelt, MD 20771 USA

[6] Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA

[7] Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 90704 USA

[8] Georgia Inst Technol, Sch Chem & Biochem, Atlanta, GA 30332 USA

[9] Georgia Inst Technol, Sch Phys, Atlanta, GA 30332 USA

[10] Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA

[11] Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA

[12] Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA

[13] Amer Museum Nat Hist, Dept Earth & Planetary Sci, Div Phys Sci, York, NY 10023 USA

[14] Carnegie Inst Sci, Dept Terr Magnetism, Washington, DC 20015 USA

[15] Brown Univ, Dept Geol Sci, Providence, RI 02912 USA

[16] Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA

[17] Univ British Columbia, Dept Earth Ocean & Atmospher Sci, Vancouver, BC V6T 1Z4, Canada

[18] DLR, Inst Planetary Res, D-12489 Berlin, Germany

[19] Lebanese Amer Univ, Dept Nat Sci, Beirut, Lebanon

[20] Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80303 USA

来源：

SPACE SCIENCE REVIEWS | 2014年 / 181卷 / 1-4期

关键词：

Mercury (planet); Space weathering; Surface processes; Exosphere; Surface composition; Space environment; BIDIRECTIONAL REFLECTANCE SPECTROSCOPY; IRON-SILICATE FRACTIONATION; SIMULATED SOLAR-WIND; DUAL IMAGING-SYSTEM; NORTH POLAR-REGION; MASS-LOSS RATES; MESSENGER OBSERVATIONS; SPECTRAL REFLECTANCE; ORDINARY CHONDRITE; OPTICAL-PROPERTIES;

D O I：

10.1007/s11214-014-0039-5

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Mercury's regolith, derived from the crustal bedrock, has been altered by a set of space weathering processes. Before we can interpret crustal composition, it is necessary to understand the nature of these surface alterations. The processes that space weather the surface are the same as those that form Mercury's exosphere (micrometeoroid flux and solar wind interactions) and are moderated by the local space environment and the presence of a global magnetic field. To comprehend how space weathering acts on Mercury's regolith, an understanding is needed of how contributing processes act as an interactive system. As no direct information (e.g., from returned samples) is available about how the system of space weathering affects Mercury's regolith, we use as a basis for comparison the current understanding of these same processes on lunar and asteroidal regoliths as well as laboratory simulations. These comparisons suggest that Mercury's regolith is overturned more frequently (though the characteristic surface time for a grain is unknown even relative to the lunar case), more than an order of magnitude more melt and vapor per unit time and unit area is produced by impact processes than on the Moon (creating a higher glass content via grain coatings and agglutinates), the degree of surface irradiation is comparable to or greater than that on the Moon, and photon irradiation is up to an order of magnitude greater (creating amorphous grain rims, chemically reducing the upper layers of grains to produce nanometer-scale particles of metallic iron, and depleting surface grains in volatile elements and alkali metals). The processes that chemically reduce the surface and produce nanometer-scale particles on Mercury are suggested to be more effective than similar processes on the Moon. Estimated abundances of nanometer-scale particles can account for Mercury's dark surface relative to that of the Moon without requiring macroscopic grains of opaque minerals. The presence of nanometer-scale particles may also account for Mercury's relatively featureless visible-near-infrared reflectance spectra. Characteristics of material returned from asteroid 25143 Itokawa demonstrate that this nanometer-scale material need not be pure iron, raising the possibility that the nanometer-scale material on Mercury may have a composition different from iron metal [such as (Fe,Mg)S]. The expected depletion of volatiles and particularly alkali metals from solar-wind interaction processes are inconsistent with the detection of sodium, potassium, and sulfur within the regolith. One plausible explanation invokes a larger fine fraction (grain size < 45 mu m) and more radiation-damaged grains than in the lunar surface material to create a regolith that is a more efficient reservoir for these volatiles. By this view the volatile elements detected are present not only within the grain structures, but also as adsorbates within the regolith and deposits on the surfaces of the regolith grains. The comparisons with findings from the Moon and asteroids provide a basis for predicting how compositional modifications induced by space weathering have affected Mercury's surface composition.

引用

页码：121 / 214

页数：94

共 454 条

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