The microwave spectrum of Mars: An analysis |
| |
| Authors: | Carl SaganJoseph Veverka |
| |
| Institution: | Laboratory from Planetary Studies, Center for Radiophysics and Space Research, Cornell University, Ithaca, New York 14850, USA |
| |
| Abstract: | A weighted least squares fit to the best available data on the Martian microwave spectrum indicates that the brightness temperature decreases from long to short wavelengths, rather than increasing as expected from the solution of the one-dimensional equation of heat conduction. Reasonable assumptions on the ratio of electrical to thermal skin depths, on internal heat sources, on ferromagnetic materials, on radiative conduction, on compaction with depth, and on surface rpughness all fail in reproducing the deduced spectrum. A thin near-surface layer of a material with high dielectric constant and high millimeter wave absorption is needed. Since Mars exhibits marked surface overturn, a condensible material, namely liquid water, seems indicated. A layer of liquid water some tens of microns thick, on the average, localized in the top few millimeters of a Martian epilith with refractive index ? 1.6 fits the microwave spectrum, and the infrared and radar data as well. The origin of such a layer of liquid water and its possible exobiological significance are discussed. The distribution of water should be nonuniform over the disk and may help explain discordant microwave observations and the anomalous variation of infrared brigthness temperature with latitude. Further millimeter wave radio and radar studies of Mars are needed. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
