C.D. Neish^a, J. Madden^b, L.M. Carter^c, B.R. Hawke^d, T. Giguere^d,e, V.J. Bray^f, G.R. Osinski^g, J.T.S. Cahill^h

^aDepartment of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL, 32901
^bFranklin and Marshall College, Lancaster, PA, 17603
^cNASA Goddard Space Flight Center, Greenbelt, MD, 20771
^dUniversity of Hawai’i at Manoa, Honolulu, HI, 96822
^eIntergraph Corporation, Box 75330, Kapolei, HI, 96707
^fLunar and Planetary Laboratory, University of Arizona, Tucson, AZ, 85721
^gCentre for Planetary Science and Exploration, Departments of Earth Sciences and Physics and Astronomy, University of Western Ontario, London, Ontario, N6A 3K7
^hThe Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723

In this study, we analyzed the distribution and properties of 146 craters with impact melt deposits exterior to their rims. Many of these craters were only recently discovered due to their unusual radar properties in the near-global Mini-RF data set. We find that most craters with exterior deposits of impact melt are small, ⩽ 20 km, and that the smallest craters have the longest melt flows relative to their size. In addition, exterior deposits of impact melt are more common in the highlands than the mare. This may be the result of differing target properties in the highlands and mare, the difference in titanium content, or the greater variation of topography in the highlands. We find that 80% of complex craters and 60% of simple craters have melt directions that are coincident or nearly coincident with the lowest point in their rim, implying that pre-existing topography plays a dominant role in melt emplacement. This is likely due to movement during crater modification (complex craters) or breached crater rims (simple craters). We also find that impact melt flows have very high circular polarization ratios compared to other features on the Moon. This suggests that their surfaces are some of the roughest material on the Moon at the centimeter to decimeter scale, even though they appear smooth at the meter scale.

Reference
Neish CD, Madden J, Carter LM, Hawke BR, Giguere T, Bray VJ, Osinski GR and Cahill JTS (in press) Global distribution of lunar impact melt flows. Icarus
[doi:10.1016/j.icarus.2014.05.049]
Copyright Elsevier

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