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

• DOI: 10.1007/s11214-014-0039-5
• Publication Date: 2014-04-23T10:36:08Z
• Authors: Deborah L. Domingue; Clark R. Chapman; Rosemary M. Killen; Thomas H. Zurbuchen; Jason A. Gilbert; Menelaos Sarantos; Mehdi Benna; James A. Slavin; David Schriver; Pavel M. Trávníček; Thomas M. Orlando; Ann L. Sprague; David T. Blewett; Jeffrey J. Gillis...; William C. Feldman; David J. Lawrence; George C. Ho; Denton S. Ebel; Larry R. Nittler; Faith Vilas; Carle M. Pieters; Sean C. Solomon; Catherine L. Johnson; Reka M. Winslow; Jörn Helbert; Patrick N. Peplowski; Shoshana Z. Weider; Nelly Mouawad; Noam R. Izenberg; William E. McClin...
• Keywords: Regolith; Space weathering; Mercury; Micrometeoroid; Bedrock; Exosphere

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