Mars: Measurements of Its Brightness Temperature at 1.85 and 3.75 cm Wavelength.", Icarus

New measurements of the microwave temperature of Mars are reported. The brightness temperatures measured during the planet’s close approach in 1967 were 182 ” f 15°K (m.e.) at 1.85 cm, and 200 ’ f 11°K (m.e.) at 3.75 cm. It is well known that information regard-ing certain physical properties of the Martian epilith can be deduced from the spectrum of the microwave brightness temperatures (see, e.g., Morrison, Sagan, and Pollack, 1969; Troitskii, 1970). In particular, the slope of the Martian radio spectrum shortward of a few centimeters wavelength is determined in most thermo-physical models by two parameters, the microwave emissivity and 6, the ratio of the electrical to thermal penetration depths in the planet’s epilith. In general, both parameters vary with wavelength. At-tempts to assemble the existing data into a well-defined spectrum have been only marginally successful, and the need for additional, adequately calibrated measure-ments has often been cited. In response to this need I measured the Martian bright-ness temperature at two wavelengths, 1.85 and 3.75 cm, during the planet’s close approach in the Spring of 1967