46th Lunar and Planetary Science Conference (2015) 1746.pdf EXPLORING SUBSURFACE LUNAR VOIDS USING SURFACE GRAVIMETRY. Kieran A. Carroll, Da- vid Hatch2, R. Ghent3, S. Stanley3, N. Urbancic3, Marie-Claude Williamson, W.B. Garry4, Manik Talwani5 1Gedex Inc., 407 Matheson Blvd. East, Mississauga, Ontario, Canada L4Z 2H2,
[email protected], 2Gedex Inc., 3University of Toronto, 4NASA GSFC, 5Rice University. Introduction: Surface gravimetry is a standard been found to be linear but discontinuous…the space terrestrial geophysics exploration technique. As noth- between such features likely represents uncollapsed ing blocks gravity, this approach can detect subsurface tube.” structures with contrasting densities, both shallow and The structure of these voids is currently unknown, deep. Recently-collected high-resolution imagery of being unobservable via imagery from orbit. Lava tube the Moon has identified numerous pits, indicative of voids presumably might be like terrestrial lava tubes -- subsurface voids. Here we analyze the anomalous - long, linear or sinuous tunnels. In [5], Wagner et al. gravity signal expected at the Moon’s surface due to speculate that “a complex plumbing system may form both localized voids and more-extensive lava tubes, in some impact melt deposits,” and that “where multi- and find that the signal can be large enough to be ple pits were found in a single pond, the pits often oc- measured with Lunar-compatible gravimeters. A po- cur in one or more small regions (~2-5 km square) tential near-term Lunar surface survey of a mare pit within the melt deposit…occasionally, several pits crater in Lacus Mortis is discussed. occur within tens of meters of each other, indicating a possible subsurface connection.” Presumably some Lunar Lava Tubes and Other Subsurface other Lunar subsurface voids might instead be much Voids: Lava tubes can form when an exposed magma more compact, resulting from the draining of a single flow cools at its top surface, forming a solid “lid” over small melt pond.