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A. Jurewicz, M. I. Blecka (Space Research Centre, Warsaw,Poland,), A. Blanco, S. Fonti, V. Orofino (Physics Dept., University of Lecce,Italy.)
Following a recent paper by Mukhin et al. ( Nature 379, 141,1996) many authors have questioned the possibility that carbonates ,probably formed in the primeval Martian environment, could have survived to the present epoch. Their considerations are also based on the lack of definite spectroscopic identification of these materials on the surface of Mars. However the assessments of the amount of carbonates present nowadays on the Martian surface have to base upon the analysis of various physico-chemical processes which could involve these compounds. An important example of such a process is the adsorption of carbon dioxide on calcium oxide surfaces whose occurrence in Martian conditions should not raise doubts. In this work we discuss the importance of such process, finding that it can efficiently counteract the destruction of carbonates due to the UV solar irradiation. As far as the problem of the detection of carbonates is concerned, it is important to note that some tentative spectroscopic identification of carbonates have been proposed as consequence of some Earth-based observations in the mid infrared. It is well known that, in such observational context the thermal radiation comes mostly from the hottest portion of the planet (i. e. the subsolar region). It is therefore possible that the temperature of the surface of Mars can play an important role in the detectivity of carbonates. For this reason we simulated the radiance spectra of Mars with a radiative transfer model finding that, when the surface temperature is low, all the carbonate features tend to disappear since their contrast becomes very small, In this case the spectroscopic identification of these materials, if they are actually present on the Martian surface, is very difficult or even impossible.
The author(s) of this abstract have provided an email address for comments about the abstract: aaj@cbk.waw.pl