metabolic activity of soil microbes On Mars Mostly Negative Result but some O 2

Metabolic activity of soil microbes on mars mostly

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metabolic activity of soil microbes On Mars? Mostly Negative Result (but some O 2 detected) Viking biological experiments on Mars Test 3: Labeled Release Experiment Expose soil to small amounts of liquid organic nutrients with a radioactive ‘label’ (C-14 or radiocarbon) On Earth: Micro-organisms metabolize carbon nutrients, releasing CO 2 or CH 4 gas (respiration) Released CO 2 or CH 4 is then detected as radioactive gas On Mars: Positive Result! (CO 2 detected)
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4/4/18 9 Test 4: Pyrolitic Release Experiment Simulate a Martian atmosphere having radioactive CO 2 Expose and then combust (burn) the soil to release any metabolized radio-carbon On Earth: Radioactive CO 2 would be detected in released gas Indicates presence of photosynthesizing cyanobacteria On Mars: Mostly Negative Result (some C-14 detected) Summary of Viking biological experiments Chemistry indicates soil is sterile, but… Biology gives 2 ‘tentative’ negatives and 1 strong positive False positives probably due to soil’s high inorganic reactivity involving ‘super-oxidants’ Loosely bound oxygen due to high UV radiation and
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  • Winter '12
  • Mars Reconnaissance Orbiter, phoenix lander, Martian Soils

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