Viking on Mars: The carbon assimilation experiments

Abstract

A fixatio~ _of atmospheric carbon, presumably into organic form, occurs in Martian surface material ~n.de~ cond1t1ons approximating the_ actual Martian o~es. The reaction showed the following character-1~t1cs. The amount of c~r.bon fixed 1s small by terrestrial standards: highest yields were observed in the light, but some dark act1v1_ty was also d_etected: and heating the surface material to 90C for nearly 2 hours had no effect on the reactwn, but heating to l 75C for 3 hours reduced it by nearly 90%. New data from M~rs do not su~port an earlier suggestion that the reaction is inhibited by traces of water. There is evidence of considerable heterogeneity among different samples, but different aliquots from the same sample are remarkably uniform in their carbon-fixing capacity. In view of its thermostability 1t is unlikely that the reaction is biological.