In their 2010 book We Are Not Alone: Why We Have Already Found Extraterrestrial Life, Dirk Shchulze-Makuch and David Darling tell the tragic story of Wolf Vishniac. In 1972 his Wolf Trap Experiment found microbes in Antarctica’s Dry Valleys that others had missed, using too rich a mixture of nutrients.
The microbes there, confirmed by others, were also missed by the Gas Chromatograph Mass Spectrometer (GCMS) scheduled to be used on the 1975 Viding missions to Mars. Later, the GCMS also missed the thermoacidophilic microbes and other extremophiles in two Mars-like environments—Geyserville and Antarctica500—probably because they were “overwhelmed” by nutrient cocktails too rich, as supplied in the pre-Viking experiments. Given these failures, why was the GCMS finding of no organics on Mars surprising?
Now, since 1977, we know a lot more about extremophiles and their requirements for mineral soup providing energy from sulfur or iron compounds. We have also detected methane in the Martian atmosphere at 10 ppb. In addition, the Phoenix lander of 2018 detected perchlorate, which explains the breakdown of organics to chloro-and dichloromethane detected by Viking.
In 1976 Viking 1 and 2 landed on the northern volcanic plains of Mars called Atopia. Two samples were scooped into a GCMS and one into a x-ray fluorescence spectrometer. In Vance Oyama’s Gas Exchange Experiment
(GEX) the Martian soil was exposed to water vapor. Early on a rapid release of oxygen was noted.
In Gil Levin’s Labeled Release (LR), an outpouring of radioactive carbon dioxide was noted when the soil sample was wetted with radioactive nutrients, but the outflow slowed down “drastically” after
70 hours. On Earth, the carbon dioxide release would have lasted a week longer if due to biological activity. On the other hand, if the release had been purely chemical, it wouldn’t have gone on for 70 hours.
When a second dose of nutrients was injected in this LR experiment, a brief release of labeled carbon dioxide was seen, then rapidly fell off by 2/3, then edged upward again.
In control experiments, where the soil samples were sterilized before incubation by preheating for three hours, the rapid release of gas dropped ten fold. In April 2012 a complexity analysis of Levins LR experiment supported the finding of “extant microbial life.” Levin later reproduced the Viking results with hydrogen peroxide-saturated titanium dioxide.
A similar indicator that microbes had been killed by the pre-heating was seen in the Pyrolytic Release experiment, in which the incorporation of radioactivity-labeled carbon dioxide and carbon monoxide into organic molecules (a definite sign of life’s organic synthesis) mimicked that expected from soil in the dry Antarctic deserts.
In any Earth experiment, this would have been called a weak positive signal for life. Chemical reactions couldn’t explain what the PR experiment microbes could–both the oxidation of nutrient soup to carbon dioxide by the LR experiment and the reductive radiation of carbon dioxide and monoxide. Biomaterial reduces carbon dioxide and turns food into energy (an oxidising reaction).
In addition, the Gas Exchange Experiment (GEX) found both oxygen and nitrogen released from the Martian soil, possibly from decomposing microbes killed by the experiment-injected water into the soil sample.
We fast forward past other observations that left the discovery of Martian life open—like the GCMS failure in Antarctica and positive LR results from samples taken under a Martian rock—to Schulze-Makuch and Darling’s conclusions. The experiments had killed off Martian organisms that used watery hydrogen peroxide as a solvent, not pure water, like Earth’s Bombadier beetle that sprays 24% hydrogen peroxide when attacked. As Mars dried up, its native organisms could have found relief with H2O2’s hygroscopic nature, its rich source of oxygen for energy, and the fact that it gets firm but does NOT crystallize (destroying
cells) at temperatures lower than 56.5oC.
In short, hydrogen peroxide organisms would explain all the results of the Viking 1 and 2 experiments. The heat probably produced the carbon dioxide measured by GCMS. Killing the microbes would have released their peroxide as oxygen and water. The initial release of carbon dioxide would be from metabolism of hydrogen peroxide organisms, which then leveled off when they were killed by exposure to the experiments’
environment, either by drowning or by bursting due to water absorption (since H2O2 is hygroscopic).
There’s more to be told about Mars and it’s possibilities for hosting life. There are “lots of caves” there to provide constant temperature, moisture, and stones for cryptobiotic critters. Hopefully, planned 2016 ExoMars and Curiosity’s Science Lab and the 2018 Mars Trace Gas Mission will confirm the finding of microbial life on Mars, past or present. We can also hope the Red Dragon mission will take off some day.