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A Closer Look at Life in the Summer of '76
by Chris McKinstry


July 31, 2001 | I remember the summer of 1976 well.

Not because our big cartoon-broadcasting neighbor to the south had just turned 200 years old. Not because the Olympics were in Canada, nor because Nadia Comaneci scored the first perfect 10 in Olympic history - causing one of the most famous computer crashes in history. Not even because Disco Duck was Top 40.

I remember the summer of 1976 vividly because Viking 1 touched down on the flat plains of Chryse Planitia on Mars, and shortly thereafter discovered the first scientific evidence of extraterrestrial life - a very big event for a nine year old spacegeek like me. Curiously though, not long after NASA announced discovering life on Mars, they retracted their statement and said what they detected was not life, but rather an unusual chemical reaction.

I heard nothing again about the Viking life detection experiments until last week - twenty-five years after the first Viking Lander landed.

The University of Southern California announced that an associate professor in the Department of Cell and Neurobiology at the Keck School of Medicine named Joseph Miller, had re-analyzed some of the original Viking data - recovered from printout because no one alive knew how to read the original archive tapes - and found something that the Viking scientists missed in 1976 - circadian rhythms!

Now this much, you’ve likely heard already in the traditional media. Let’s look closer.

The Original Experiments:

Viking I and Viking 2 (which landed some weeks after Viking 1 on September 3 on Utopia Planitia) carried identical packages of biology experiments called GEX/LR/PR, an acronym for: gas exchange, labeled release and pyrolytic release.

Schematic of the Viking Labeled Release Experiment

The Viking LR experiment was the simplest and most sensitive to microorganisms of the three experimental packages. It was based on the widespread metabolism by microorganisms of Miller-Urey compounds - the goop that Miller and Urey got when they famously simulated lightning in a simulated pre-biotic atmosphere - and involved applying a small drop of Miller-Urey goop to the center of a soil sample. Unlike the Pyrolytic Release (PR) experiment, it required no intervention (an optical filter) to prevent a false positive; unlike the Gas Exchange (GEx) experiment, it did not adjust the raw data (factoring in presumed coefficients of the Martian soil and adjustments for probable gas sample size) prior to interpretation.

The goop the Viking probes carried to Mars was designated VM1, and was a solution of formate, glycine, D-alanine, L-alanine, D-lactate, L-lactate, and glycolate, each uniformly labeled with radioactive Carbon-14. Any radiation detected evolving from gas sampling of the VM1 moistened soil would indicate microbial activity, as the radioactive Carbon-14 could not leave the soil without being actively processed by living organisms. Following such a positive response, a duplicate of the original sample is heated to impair or destroy any organisms present. After cooling, that sample is tested exactly as was the one that produced the positive result. A positive response from the second sample indicates that the response of the first was non-biological in nature, while a negative response, demonstrating that the causative agent had been deactivated by heat, completes the evidence for life.

Mars and Terrestrial LR Soil Test Results

Many soils and microbial cultures of a wide variety of species were tested (see diagram). No sample with demonstrated living organisms failed to respond. The controls readily confirmed biological activity. (Only several of the hundreds of soils were sterile.) The metabolism of as few as 50 cells was readily detected. In a final test of an LR flight instrument, a California soil was placed under the experimental conditions to prevail on Mars. After 3 days of the reduced atmospheric pressure, humidity and temperature, the VM1 was injected. Radioactive gas immediately evolved and increased through the standard 8-day LR test period. A second injection of nutrient then produced an increased response. A duplicate of the test soil was heated to 160 degrees C for 3 hours and, after cooling, was tested. Essentially no response from the heated sample occurred, completing the evidence that there had been living organisms in the first sample and that they had survived exposure to the Martian test conditions.

The results from the Viking 1 Site and the Viking 2 Site, some 4,000 miles away, produced similar positive responses. After eight sols (one Martian sol = 24.66 Earth hours) of continuing, but slowing, evolution of gas, the soil samples at both sites were injected with nutrient a second time. Each sample promptly reabsorbed approximately 20% of the gas evolved to that point. A duplicate of the active sample was heated at 160 degrees C for 3 hours and, upon testing, gave a nil response. In additional controls, 60% less gas was evolved after heating a duplicate sample to 46.0 degrees C. After another duplicate sample was heated to 51degrees C, the response became erratic and produced 90% less gas than did the active sample. Active Mars soils, enclosed in the Viking sample distribution box and held at approximately 10 degrees C for 2 months at one site and 3 months at the other, showed no activity upon testing

These results were classified by NASA as chemical rather than biological. This was primarily because no organic compounds were found in Martian soil analyzed by the Viking Gas Chromatograph Mass Spectrometer (GCMS) and because it was assumed that there is no liquid water on Mars, and that its absence would make life impossible.

All of this, and the fact that NASA has never sent any more biological experiments to Mars says to me that science just wasn’t ready to find life on another world in 1976.

Circadian rhythms Discovered

In 1999 the aforementioned Joseph Miller, who had worked for NASA in the early 1980s, studying the effects of zero gravity on circadian rhythms in squirrel monkeys, began writing a proposal to NASA to do biology on future Mars expeditions. It was then that he saw a figure in a geophysical journal taken from the data from the Viking Lander 2 experiment—a figure that showed highly periodic gas release in the Viking LR experiments.

Although the science of biological clocks hadn’t been advanced enough at the time of the Viking experiments to help the researchers make their case, it had come a long way in the intervening years. And Miller immediately knew he had something potentially exciting on his hands.

Looking at the old NASA data, Miller found something remarkable—something, he says in a USC press release, that went unremarked-upon in the original papers. "The signal itself not only had a circadian rhythm," declares Miller, "but it had a precise circadian rhythm of 24.66 hours—which is particularly significant, because it’s the length of a Martian day."

More specifically, says Miller, the fluctuations in gas emissions seem to be entrained to a 2 degrees C fluctuation inside the lander, which in turn reflected not-quite-total shielding from the 50 degrees C fluctuation in temperature that occurs daily on the surface of Mars. Temperature-entrained circadian rhythms, even to a mere 2-degree C fluctuation, have been observed repeatedly on earth.

As for the original concerns of the dubious chemists, who thought the same sort of signal could simply be coming from highly reactive, non-organic compounds in the soil, Miller says such a scenario would be almost impossible to imagine. "For one thing," he explains, "there has since been research that shows that superoxides exposed to an aqueous solution—like VM1—will quickly be destroyed. And yet, the circadian rhythms from the Martian soil persisted for nine straight weeks."

"There is no reason for a purely chemical reaction to be so strongly synchronized to such a small temperature fluctuation," he adds. "We think that in conjunction with the strong indications from Mars Observer images that show water flowed on the surface in the recent past, a lot of the necessary characteristics of life are there. I think back in 1976, the Viking researchers had an excellent reason to believe they’d discovered life; I’d say it was a good 75 percent certain. Now, with this discovery, I’d say it’s over 90 percent. And I think there are a lot of biologists who would agree with me."

© 2001, Chris McKinstry

Links: Life on Mars -

Chris McKinstry is a Canadian living in Chile where he operates the world's largest optical telescope for the European Southern Observatory. He is also the creator of the Mindpixel Digital Mind Modeling Project, the world's largest AI effort.



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