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Dr. Gilbert Levin's Mars Blog

Gilbert V. Levin

Honorary Professor, Buckingham Centre for Astrobiology of Buckingham University



Or rather, "Hell, yes!" We not only have evidence for life on Mars, we have had proof that there is life in Martian soil for nearly 40 years. Put another way, if the ice machine in a McDonald's on Mars had been tested by the Viking landers for the Greater Olympus Mons City Health Department, they would have shut the place down in 1976. That's the kind of proof NASA has, and it is not that complicated, though some would have us believe that it is.


The Viking LR test conducted on Mars was the standard analysis used to test for microorganisms described in the Standard Method for the Examination of Water and Wastewater, published by the American Public Health Association, the Water Environment Federation and the American Waterworks Association and used by public health departments world-wide for decades.


Here's how it works. An aqueous solution of the sugar lactose is mixed with the sample to be tested for microbial contamination. If they are present, microorganisms metabolizing the lactose produce gas bubbles, the visual observation of which is the evidence for microbial contamination. The Viking LR added several additional organic nutrients, all of which were thought to have formed on early Earth (and Mars) and to have participated in the genesis and evolution of life. In other words, it was a yummy stew for microorganisms, even primeval sorts. But the LR went one step further. It applied the key part of any scientific experiment, a control. This was added to preclude the possibility that some exotic chemical on Mars might cause a false positive. The control was done by heating a duplicate sample of any soil yielding a positive result to a temperature to kill any microbes, but not high enough to destroy chemicals likely to interfere. After cooling, the control was tested in the LR: a negative response testified that the original positive response was biological; a positive response indicated the response had been chemical.


To increase the sensitivity and speed of the method of the Viking tests, so that the experiments might be completed before possible spacecraft or communication failure, the nutrients were tagged with radioactive carbon. Any gas produced from the nutrient solution would be radioactive, permitting its detection long before visible bubbles formed. Thus, the LR was the Standard Method, merely augmented with additional nutrients and radioactive food sources.


Viking 1 landed on July 20, 1976, and Viking 2 landed, some 4,000 miles away on the Martian surface September 3rd of that same year. A total of four tests for life were positive. All five controls that were conducted supported the biological nature of these positive responses. Their amplitudes and kinetics were virtually the same as produced by many of the thousands of tests of microbial soils performed on Earth -- which tests never produced a false result, attesting to the reliability of the method. As noted, this would be proof enough if it were run by the health department in any city on Earth to shut down the local McDonald's.


The Viking LR Mars results were largely discounted in 1976. Why?


The principal reasons initially given by NASA were: the failure of the Viking organic analysis instrument (GCMS -- gas chromatograph mass-spectrometer) to find any organic matter, and/or the presence of an unidentified-highly oxidizing-lethal substance in the Martian soil, and/or the lack of liquid water in the Martian soil. How have these reasons held up over the years since Viking landers completed their missions?


Several post-Viking publications have found a variety of faults with the Viking GCMS, effectively impugning its results. Insensitivity or equipment failure is the most likely cause the GCMS failed in its mission. Furthermore, the Viking Pyrolytic Release (PR) experiment showed that organic compounds were being formed and accumulating in the Martian soil.


Curiosity, NASA's most recent rover sent to Mars, has reported finding several types of low molecular weight organics. But, like the results of the Viking PR, these are not complex enough to support the definitive claim to life -- yet. Curiosity has not, as of this writing, reported on results from its liquid extraction experiment for detecting organics as complex as amino acids. Since the finding of complex organic compounds by the Viking GCMS in 1976 would have led to instant acceptance of the Viking LR results, it seems only logical that, should Curiosity find them now, the same conclusion should result. Thus, data from the liquid extraction method applied to Martian soil are eagerly anticipated.


The Mariner 9 IRIS experiment, several Earth-based observations, and results from Pathfinder, Phoenix, and now Curiosity have demonstrated very clearly that there is no highly oxidizing substance like peroxide, or any other strong oxidant dominating the Martian soil. "The chemical analysis of the sample also revealed compounds in varying states of oxidation -- for example both sulfate and sulfide. This is significant because it demonstrates that the environment was not violently oxidizing (emphasis added)," Joe Michalski, key Curiosity scientist, as reported in Chemistryworld, by Simon Hadlington, Mar. 18, 2013.


Curiosity has also supported Viking's finding of liquid water in the Martian soil. Figure 1 (view here), from Curiosity's analysis of the 4th John Klein rock sample, shows water vapor streaming off the sample when heated from about 0 deg. to about 13 deg. C. Curiosity data also show that the atmospheric pressure never falls below 6.1 mb, the triple point for water, and that the ground temperature frequently goes above 0 deg. C on the soil in Gale Crater. These conditions ensure that water in the sample is routinely in liquid state.


To date, of the countless experiments performed and abiotic theories proposed, none has been proven scientifically tenable in explaining away the Viking test and control data as evidence for life. While some experiments have shown that a variety of oxidants can react with one or more of the LR nutrients to evolve gas, none has met the thermal control data. This includes the recently proposed perchlorates. Either by oversight or by careful selection of data, none of the abiotic explanations addresses all of the control data, especially the one most difficult to explain -- the loss of the activity of the sample after storage for two months in a dark box at the modest temperature of 10 deg. C (a temperature frequently reached diurnally on the Martian surface). These "NASAyers" never discuss the far more likely explanation -- death of the organisms isolated from their native Martian environment.


The proof of life on Mars is the hard data of the Viking LR, adequately replicated at two Martian sites, and supported by virtually every new finding about the habitability of Mars that has arisen in the 40 intervening years. Namely, 1. Positive results from a universally accepted test; 2. Negative responses from well-designed controls; and 3. The absence of any sustainable experiment or theory to provide a non-biological explanation of the data in points 1 and 2, above. Supporting this strong positive proof, are the continual findings of extremeophile organisms living happily in the most Mars-like environments on Earth, and the increasing knowledge of Mars' habitability, as recently confirmed by Curiosity


What more is needed to constitute proof of extant, native microbes on Mars? Maybe further confirmation of that proof by Curiosity's finding of complex organic matter in the Martian soil might add the somehow lacking reassurance the "Flat Mars Society" seems to require. Ultimately, scientific reason will prevail. And, the paradigm will change, alas, once more deflating man's ego as the center of the universe and its home planet being the only one hosting life forms. About time after nearly 40 years NASA, wouldn't you say?


Gilbert V. Levin responds to Christopher P. McKay

Gilbert V. Levin responds to Christopher P. McKay

NASAyers refuse to confront the control phase of the Viking LR experiment. The biology-consistent thermal responses to the active agent in the Martian soil completely rule out any role for perchlorate or hypothesized cosmic radiation products of perchlorate. If the perchlorate and/or derivatives became inactive at 10 deg. C in the distribution box of Viking, how did they survive 10 deg. C on the surface of Mars, which temperature, and above, has been routinely recorded by Viking, Pathfinder, Phoenix and Curiosity?

Look. NASA can choose to ignore the substantial and mounting evidence that Mars hosts native, living microorganisms. But, make no mistake. If NASA does so, it changes the nature of space exploration. It forgives, for an indefinite amount of time, a failure to mount definitive missions to answer the most important question humans have ever posed -- "Are We Alone?"

We know how to conduct such experiments. We have the tools right now. And we are not far from being able to conduct direct observations by human explorers as was shown at the recentHumans to Mars Summit conducted by Explore Mars, Inc.

Our efforts to accomplish this should be redoubled. To derail them now, with missions like asteroid retrieval and Low Earth Orbit activities best left to military and commercial space, is unacceptable. This is especially so, since we have come so very close to absolute confirmation that Martian life exists. It is a waste of all science done to date that, at the very minimum, must leave us operating on the well-supported assumption that life exists on Mars(To learn more, watch this video).And it is what the American taxpayer wants from space exploration.

True, talk is cheap -- but, debate is desperately needed before we make a terribly wrong turn in space. We propose that an independent study be funded by Congress. It should be aimed at conserving the dwindling taxpayer dollar by focusing on a thorough review of present data, and the design of near-term missions that will resolve this debate once and for all. We invite our worthy "opponent" and good friend to join us in a live debate in front of an appropriate joint Congressional committee on this important topic. American taxpayers deserve such a frank appraisal of the direction of their own space program. Humans deserve the answer such confirmation will bring.


Dear Editor:


The Mars Science Laboratory, “Curiosity, may have confirmed the presence of current liquid water on Mars.  NASA-released Figures 1 – 3, discussed by the author at the Humans 2 Mars Summit on May 7, 2013, provide the evidence.


Figure 1: atmospheric pressure, over the entire 180 sols reported, never fell below the triple point for water, 610 Pa (6.1 mb).  Figure 2: atmospheric and ground temperatures frequently rose to, and above, the freezing point of water.  Figure 3:  water vapor is detected coming from the sample.  Vapor even comes from the sample at, and slightly above, freezing, indicating water in liquid phase in the sample. 


Figure 4, based on the phase diagram for water in the CRC Handbook of Chemistry and Physics, shows that the temperature range for liquid water at 6.1 mb atmospheric pressure is 0 to about 14 deg. C (the cross-hatched region), within which the cited Curiosity data fall. They, thus, imply liquid water in the sample.  Perhaps it is moisture deposited from the atmosphere onto the John Klein rock powder. It is unlikely that the vapor source was atmospheric, taken in with the sample, without having been a liquid in the sample. Were that the case, atmospheric CO2 would also have been taken in with the sample.  However, Figure 3 shows CO2 appearing only after the sample was heated to about 90 deg. C. 

The most important implication from these data is that liquid water may frequently exist in the current Martian regolith.  





Gilbert V. Levin

Arizona State University, Tempe




Fig. 1.  Atmospheric Pressure Over 180 Sols



Fig. 2.  Temperatures of Atmosphere and Surface


Fig. 3.  Water Vapor Released from Sample

FIG. 4.  Phase Diagram for Water Showing Mars Envelope