NH11A-1896
Characterization of the Interior Density Structure of Near Earth Objects with Muons

Monday, 14 December 2015
Poster Hall (Moscone South)
Thomas H Prettyman1, Mark V Sykes2, Richard S Miller3, Lawrence S. Pinsky4, Anton Empl5, Michael C Nolan6, Steven L Koontz7, David J Lawrence8, David W Mittlefehldt9 and Brandon D. Reddell9, (1)Planetary Science Institute, Albuquerque, NM, United States, (2)Planetary Science Institute Tempe, Tempe, AZ, United States, (3)University of Alabama in Huntsville, Huntsville, AL, United States, (4)University of Houston, Physics, Houston, TX, United States, (5)University of Houston, Houston, TX, United States, (6)University of Arizona, Tucson, AZ, United States, (7)NASA Johnson Space Ctr, Houston, TX, United States, (8)Johns Hopkins University, Baltimore, MD, United States, (9)NASA Johnson Space Center, Houston, TX, United States
Abstract:
Near Earth Objects (NEOs) are a diverse population of short-lived asteroids originating from the main belt and Jupiter family comets. Some have orbits that are easy to access from Earth, making them attractive as targets for science and exploration as well as a potential resource. Some pose a potential impact threat. NEOs have undergone extensive collisional processing, fragmenting and re-accreting to form rubble piles, which may be compositionally heterogeneous (e.g., like 2008 TC3, the precursor to Almahata Sitta). At present, little is known about their interior structure or how these objects are held together. The wide range of inferred NEO macroporosities hint at complex interiors. Information about their density structure would aid in understanding their formation and collisional histories, the risks they pose to human interactions with their surfaces, the constraints on industrial processing of NEO resources, and the selection of hazard mitigation strategies (e.g., kinetic impactor vs nuclear burst). Several methods have been proposed to characterize asteroid interiors, including radar imaging, seismic tomography, and muon imaging (muon radiography and tomography). Of these, only muon imaging has the potential to determine interior density structure, including the relative density of constituent fragments. Muons are produced by galactic cosmic ray showers within the top meter of asteroid surfaces. High-energy muons can traverse large distances through rock with little deflection. Muons transmitted through an Itokawa-sized asteroid can be imaged using a compact hodoscope placed on or near the surface. Challenges include background rejection and correction for variations in muon production with surface density. The former is being addressed by hodoscope design. Surface density variations can be determined via radar or muon limb imaging. The performance of muon imaging is evaluated for prospective NEO interior-mapping missions.

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