The gas exchange experiment for life detection: The Viking Mars Lander

The Gas Exchange Experiment of the Viking mission accepts a sample of Martian soil, incubates this soil with nutrient medium, and periodically samples the enclosed atmosphere over this soil for the gases H₂, N₂, O₂, CH₄, Kr, and CO₂. These gases are analyzed by an automated gas chromatograph, and the data are transmitted to Earth. The design of the experiment and the qualitative and quantitative changes, if any, of gas composition should allow conclusions to be made on the presence of life on Mars. Data and theory substantiating this approach are presented.