THE NASA GOVERNMENT HAVE LADIR GROUND PENETRATION RADAR THAT SEES 100

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Description

THE NASA GOVERNMENT HAVE LADIR GROUND PENETRATION RADAR THAT SEES 100 MILES INTO THE EARTH. Ground penetrating radar geologicfield studies of the ejectaof Barringer Meteorite Crater, Arizona, as a planetary analog Ground penetrating radar (GPR) has been a useful geophysical tool in investigating avariety of shallow subsurface geological environments on Earth. Here we investigate the capabilities of GPR to provide useful geologic information in one of the most commongeologic settings of planetary surfaces, impact crater ejecta. Three types of ejecta aresurveyed with GPR at two wavelengths (400 MHz, 200 MHz) at Meteor Crater, Arizona,with the goal of capturing the GPR signature of the subsurface rock population. In order to“ground truth”the GPR characterization, subsurface rocks are visually counted andmeasured in preexisting subsurface exposures immediately adjacent to and below the GPRtransect. The rock size-frequency distribution from 10 to 50 cm based on visual counts iswell described by both power law and exponential functions, the former slightly better,reflecting the control of fragmentation processes during the impact-ejection event. GPRcounts are found to overestimate the number of subsurface rocks in the upper meter(by a factor of 2–3x) and underestimate in the second meter of depth (0.6–1.0x), resultsattributable to the highly scattering nature of blocky ejecta. Overturned ejecta that isfractured yet in which fragments are minimally displaced from their complement fragmentsproduces fewer GPR returns than well-mixed ejecta. The use of two wavelengths anddivision of results into multiple depth zones provides multiple aspects by which tocharacterize the ejecta block population. Remote GPR measurement of subsurface ejecta infuture planetary situations with no subsurface exposure can be used to characterize thoserock populations relative to that of Meteor Crater.