Results of a Radiometric Moon-Mapping Investigation at 3 Millimeters Wavelength

Abstract

view Abstract Citations (8) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Results of a Radiometric Moon-Mapping Investigation at 3 Millimeters Wavelength Gary, B. Abstract This is the second of two papers describing an attempt to determine the nature of the lunar surface material from an analysis of the monthly variation of the Moon's 3.3-mm wavelength thermal emission. The Aerospace Corporation 15-foot-diameter radio telescope was used to construct high angular resolution radiometric maps consisting of brightness temperature contours on the Moon's disk for 14 representative lunar phases An analysis has been performed on the thermal behavior of five maria and portions of a large highland region. The final results of this analysis are reported in the present paper. The observed temperature variation during a lunation has been compared with predictions based on a model for the lunar surface which allows for the existence of vertical and horizontal inhomogeneities of certain parameters of the lunar material. Values for these parameters have been subjected to constraints imposed by infrared observations of the lunar nighttime surface temperature. No combination of parameter values permitted by these constraints can account for the microwave observations. Suggestions for possible improvements of the lunar model are given. Comparisons of the thermal behavior of different locations on the Moon reveal that the lunationaveraged temperature of the five maria investigated exceeds that of the highlands by 2.60 * 0.20 K, whereas albedo considerations lead to an expected temperature excess of only 0.80 i 030 K. An attempt is made to explain this discrepancy by associating the mare surfaces with either a greater abundance of rock (exposed, or close to the surface) or a smaller value for the lunar material's thermal inertia reciprocal, . The mare-highland temperature excess varies during a lunation between 0 K and +60 K for Mare Nubium, Mare Imbrium, and the mare region near Copernicus. Mare Serenitatis exhibits a 90 K variation, and the temperature excess of Mare Tranquilitatis appears to remain constant. An unsuccessful attempt to explain these variations provides further demonstration of the need for a more sophisticated model for the lunar surface. Publication: The Astrophysical Journal Pub Date: January 1967 DOI: 10.1086/148996 Bibcode: 1967ApJ...147..245G full text sources ADS |