DOI: 10.1016/j.epsl.2020.116274
论文题名: Bulk composition of regolith fines on lunar crater floors: Initial investigation by LRO/Mini-RF
作者: Heggy E. ; Palmer E.M. ; Thompson T.W. ; Thomson B.J. ; Patterson G.W.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 541 语种: 英语
中文关键词: dielectric properties
; ice
; Moon
; regolith
英文关键词: Dielectric properties
; Excavation
; Moon
; Polarimeters
; Radar
; Bulk compositions
; Crater diameter
; Equatorial regions
; Lunar crusts
; Metal abundances
; Optimal target
; Polarimetric radars
; Polarimetric scattering
; Floors
; backscatter
; breccia
; crater
; dielectric property
; lunar crust
; mineralogy
; Moon
; radar
; regolith
英文摘要: Identifying polarimetric radar signatures of ice in smooth regolith fines on the floors of permanently shadowed lunar craters is hindered by uncertainties in their dielectric properties. We address this deficiency through polarimetric radar analysis of surface backscatter to derive the dielectric constant (εr ′) of smooth, rock-free regolith fines covering brecciated crater floors observed by Mini-RF, which offer ideal locations for unambiguous retrieval of surface εr ′ from linear polarimetric scattering models and CPR analysis for volatile identification. Specifically, we select fines covering crater fills in north polar and equatorial regions to constrain the range of variability of εr ′ as a function of latitude and crater diameter, where we hypothesize that the latter is indicative of the excavation depth of these fines. Our observations suggest that there is measurable variability in the dielectric properties of fines on lunar crater floors as a function of crater size and potentially with impact excavation depth, suggesting that small craters <5-km in diameter have εr ′ ranging from 2.3-to-3, and large ones >5-km have higher values of εr ′ that range from 3-to-3.8. We find that the most plausible explanation for the observed variability of εr ′ of regolith fines on crater floors is mineralogical differences, suggesting an increase in metal abundance in the original excavated substrate with depth, i.e., in the uppermost kilometer of the lunar crust. Finally, we suggest that regolith fines on the floors of permanently shadowed craters <5 km in diameter are optimal targets for the unambiguous detection of water-ice enrichment using S-band radar observations. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165017
Appears in Collections: 气候变化与战略
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作者单位: University of Southern California, Ming Hsieh Department of Electrical and Computer Engineering, 3737 Watt Way, Los Angeles, CA 90089, United States; Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States; Department of Earth and Planetary Sciences, The University of Tennessee Knoxville, 1621 Cumberland Avenue, Knoxville, TN 37996, United States; The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
Recommended Citation:
Heggy E.,Palmer E.M.,Thompson T.W.,et al. Bulk composition of regolith fines on lunar crater floors: Initial investigation by LRO/Mini-RF[J]. Earth and Planetary Science Letters,2020-01-01,541