%0 Journal Article
%T Processes governing the VIS/NIR spectral reflectance behavior of lunar swirls
%A A. A. Berezhnoy
%A A. Bhardwaj
%A A. Grumpe
%A C. W£¿hler
%A K. Wohlfarth
%A M. Bhatt
%A M. Hess
%A V. V. Shevchenko
%J -
%D 2020
%R 10.1051/0004-6361/201937299
%X We investigated six bright swirls associated with magnetic anomalies of variable strength using Chandrayaan-1 Moon Mineralogy Mapper (<i>M<i/><sup>3<sup/>) hyperspectral image data. We examined the 3 <i>¦Ì<i/>m absorption band generally ascribed to solar wind-induced OH/H<sub>2<sub/>O and spectral trends in the near-infrared wavelength range at on-swirl and off-swirl locations. We found that the 3 <i>¦Ì<i/>m absorption band is weaker at on-swirl than at off-swirl locations and shows only weak variations with time-of-day. This result is consistent with magnetic anomaly shielding that reduces solar wind interaction with the surface. For a small swirl structure in Mare Moscoviense, we found the 3 <i>¦Ì<i/>m absorption band to be similar to that of its surroundings due to the absence of strong magnetic shielding. Our spectral analysis results at on-swirl and off-swirl locations suggest that the spectral trends at on-swirl and off-swirl locations cannot always be explained by reduced space-weathering alone. We propose that a combination of soil compaction possibly resulting from the interaction between the surface and cometary gas and subsequent magnetic shielding is able to explain all observed on-swirl vs. off-swirl spectral trends including the absorption band depth near 3 <i>¦Ì<i/>m. Our results suggest that an external mechanism of interaction between a comet and the uppermost regolith layer might play a significant role in lunar swirl formation
%U https://www.aanda.org/articles/aa/full_html/2020/07/aa37299-19/aa37299-19.html