Mars: Subsurface Properties from Observed Longitudinal Variation of the 3.5-mm Brightness Temperature

摘要

Measurements at 3.5 mm of the disk-average brightness temperature of Mars during the 1978 opposition can be represented by T sub B (Mars, 3.5 mm, Jan/Feb 1978) = 198(+ or - 1) + 10(+ or - 2) cos (CML + 10(+ or - 6) K. (The errors cited are from the internal scatter; the estimated absolute calibration uncertainty is 3%). This longitudinal variation must be taken into account if Mars is to be used as a calibration source at millimeter wavelengths. The total range of the 3.5-mm variation is three to four times larger than both the 2.8-cm and 20-micrometer variations. This unexpected result can possibly be explained by subsurface scattering from rocks < or approx. 1.5-cm. (Author)