Models of the Lunar Surface with Temperature-Dependent Thermal Properties.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Models of the Lunar Surface with Temperature-Dependent Thermal Properties. Linsky, Jeffrey Abstract For the interpretation of recent data on lunar thermal emission, I have written a Fortran encoded computer program to solve the heat conduction equation and to compute radio brightness temperatures for a medium having conductive and radiative energy transport and characterized by arbitrary temperature- and depth-dependent thermal properties. This program will also solve periodic heat conduction problems of a more general nature. A number of models were constructed with a range of temperature-dependent conductivities and specific heats, but each was consistent with the minimum surface temperature of 900 K observed l~y Low (Astrophys. J. 142, 806, 1965) at the morning terminator. All of these models predict infrared and radio brightness temperatures for eclipses and lunations which agree favorably with high-resolution data for the center of the lunar disk. If there are no internal heat sources, a significant increase in the mean radio brightness temperature with wavelength occurs when the conductivity, but not the specific heat, increases with temperature. This increase in the mean radio brightness temperature results from the nonlinear nature of heat conduction under these circumstances, and is sufficient to explain the observed increase with wavelength described by Krotikov and Troitskii (Soviet Phys. Usp. 6, 841, 1964), without requiring as a postulate an unusually high level of radioactivity in the moon. The general behavior of silicates at lunar temperatures and laboratory measurements of probable lunar materials suggest that radiative energy transport is the most probable mechanism to account for an increase in the conductivity with temperature. Several models in which radiative transfer and thermal conduction are of comparable importance at 3500K agree favorably with the data of Krotikov and Troitskii. The present findings support the hypothesis that porous or frothy material characterize the lunar surface at least to a depth of 20 cm, and are in agreement with radar depolarization studies. This research was sponsored by NASA. Publication: The Astronomical Journal Pub Date: 1966 DOI: 10.1086/110133 Bibcode: 1966AJ.....71S.168L full text sources ADS |