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Published September 30, 1977 | Published
Journal Article Open

Viking on Mars: The carbon assimilation experiments


A fixation of atmospheric carbon, presumably into organic form, occurs in Martian surface material under conditions approximating the actual Martian ones. The reaction showed the following characteristics: The amount of carbon fixed is small by terrestrial standards; highest yields were observed in the light, but some dark activity was also detected; and heating the surface material to 90°C for nearly 2 hours had no effect on the reaction, but heating to 175°C for 3 hours reduced it by nearly 90%. New data from Mars do not support 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 it is unlikely that the reaction is biological.

Additional Information

© 1977 American Geophysical Union. Received April 1, 1977; revised June 6, 1977; accepted June 6, 1977. We owe a debt of gratitude to all those connected with the Viking mission, whose efforts helped make the mission the historic achievement that it has been. We acknowledge in particular the important contributions made by Ron Gilje, Fred Brown, and Steve Loer to the successful operation of our instrument during the active phase of the mission, and we thank Paul K. Cartier III and William Ashley for their invaluable technical assistance in the laboratory phases of the investigation. This work was supported by NASA contracts NAS1-12311 (to N.H.H.) and NAS1-13422 (to J.S.H.) and NASA grants NGR-05-002-308 (to N.H.H.) and NSG-7069 (to J.S.H.).

Attached Files

Published - Horowitz_et_al-1977-Journal_of_Geophysical_Research-_Solid_Earth__1978-2012_.pdf



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