Volatile inventories on Mars

Predictions for the total inventory of outgassed volatiles on Mars can be developed by studying volatiles in meteorites, terrestial rocks, and the atmospheres of Venus, the Moon, and the Earth. Two models are presented following the basic assumption that the devolatilization of Mars has been analogous to that of the Earth. The recent discovery of a high abundance of argon in the Martian atmosphere appears to indicate that Mars has outgassed as completely as the Earth, but present uncertainties and lacunae in the essential data set permit several other interpretations.