Paper No. 178-2
Presentation Time: 9:00 AM-6:30 PM
UNDERSTANDING REGOLITH PHYSICAL PROPERTIES OF ATMOSPHERELESS SOLAR SYSTEM BODIES USING REMOTE SENSING PHOTOPOLARIMETRIC OBSERVATIONS: PLANETARY SURFACE ANALOGS
NELSON, Robert M.1, BORYTA, Mark2, HAPKE, Bruce W.3, MANATT, Kenneth S.4, SHKURATOV, Yuriy5, PSAREV, Vladimir5, VANDERVOORT, Kurt6, KRONER, Desiree7, NEBEDUM, Adaeze2, VIDES, Christina8 and QUIÑONES, John9, (1)Planetary Sciences Institute, Pasadena, CA 91104; Department of Earth Sciences and Astronomy, Mt. San Antonio College, 1100 N. Grand Avenue, Walnut, CA 91789, (2)Department of Earth Sciences and Astronomy, Mt. San Antonio College, 1100 N. Grand Avenue, Walnut, CA 91789, (3)University of Pittsburg, Pittsburg, PA 15260, (4)Jet Propulsion Laboratory, Pasadena, CA 91109, (5)Karazin University, Karkiv, Ukraine, (6)Department of Physics, California Polytechnic Institute/Pomona, Pomona, CA, (7)University of California at Los Angeles, Los Angeles, CA, (8)Department of Physics, California Polytechnic Institute/Pomona, Pomona, CA; Department of Earth Sciences and Astronomy, Mt. San Antonio College, 1100 N. Grand Avenue, Walnut, CA 91789, (9)California State University, Los Angeles, Los Angeles, CA; Department of Earth Sciences and Astronomy, Mt. San Antonio College, 1100 N. Grand Avenue, Walnut, CA 91789, mboryta@mtsac.edu
We studied the polarization and reflective properties of a suite of analogs for regolith material of high-albedo atmosphereless solar system bodies (ASSB) of the outer solar system. The angular scattering properties of thirteen well-sorted size fractions of aluminum oxide (Al
2O
3) powders were measured in the laboratory with a goniometric photopolarimeter (GPP) of unique design.
Our results provide insight in support of efforts to understand the unusual reflectance and negative polarization behavior observed near small phase angles that has been reported over several decades on highly reflective outer solar system ASSBs such as the asteroids 44 Nysa, 64 Angelina (Harris et al., 1989) and the Galilean satellites Io, Europa and Ganymede (Rosenbush et al., 1997; Mishchenko et al., 2006).
Our measurements are consistent with the hypothesis that the surfaces of these ASSBs effectively scatter electromagnetic radiation as if they were extremely fine-grained with void space ≥~95%, and grain sizes of the order ≤ λvis.
Our results constrain efforts to deploy surface landers on high ASSBs such as Europa. A spacecraft landing on Europa’s surface would require wheel or footpads that would protect it from settling deeply into the surface.
Refs: Harris et al., 1989. Icarus 81, 365–374; Mishchenko et al., 2006. Applied Optics, 45, 4459-4463; Rosenbush et al, 1997, Astrophys. J. 487, 402–414.
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