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 Seasonal color changes on Martian surface imitate terrestrial plant life. 3. The Search for Life on Mars The official scientific consensus is that Mars is a dead world, and probably has always been so. But only a generation ago, the scientific consensus was quite different, as the respected astronomer E.C. Slipher of Lowell Observatory wrote in 1962:
Mars is an inhospitable world by Earth standards, but it is the best alternative home for life in our solar system. Although largely a frigid world, Mars does host balmy temperatures as high as eighty degrees Fahrenheit on the equator. And water, so fundamental for the existence of life, is present in those gleaming ice caps. The astronomer Patrick Moore relates that pessimistic views were once held about the water content of the caps: "As recently as 1954, Gerard de Vaucouleurs wrote that the cap thickness could not be more than a couple of inches, and many astronomers dismissed it as being nothing more than a deposit of hoar-frost."[2] Others thought that the caps were composed entirely of carbon dioxide. But Mariner 9 and the Vikings photographed polar ice cap layers in thicknesses of hundreds of feet, and confirmed a watery composition. At least in frozen form, water is not scarce on Mars. Atmosphere is scarce. Surface pressure is presently 7 millibars (Earth's is 1000). Water either freezes or boils at such low pressure; it will not stay liquid. For humans and animals, the Martian atmosphere may as well be vacuum. Even so, some forms of terrestrial life can survive under Martian conditions. Some microorganisms and even macroscopic plants on Earth can extract water vapor from air, rocks, and ice; cell membrane pressure and internal metabolic heat enable them to keep their internal water supply in a liquid state. Still others keep water liquid at subzero temperatures via a natural 'anti-freeze.' These tricks of nature have allowed microorganisms to survive in the sandstone rocks of perpetually-frozen Antarctica[3] -- an environment not unlike Mars in temperature range. And it turns out that some plants actually thrive better in frigid temperatures when oxygen is lacking. Using artificial environments known as 'Mars Jars' (duplicating Martian surface conditions as much as possible), scientists have been able to show that certain humble earthly plants -- lichens in particular -- could survive on the planet.[4] In theory, these plants should flourish in patches large enough to be seen from Earth. And they may indeed have been. For many decades, astronomers reported seeing color changes on the planet in synchronization with the seasons, as Slipher observed in 1955:
Additionally, spectrum analysis of the light reflected by the dark regions shows the presence of the carbon-hydrogen bonding found in organic molecules. The astronomer V.A. Firsoff noted many years ago:
Another astronomer, E. J. Opik, observed in 1950 that given its frequent dust storms, Mars should by now be completely covered with light-colored dust. So why are there still dark regions? Opik suggested that these regions were populated with plants, which gave them their color. Once a storm settled, the plants grew up through the dust layer a few weeks later and the region appeared dark again. This paralleled observations.[7] Ultraviolet radiation may seem a sure killer, given the lack of protection provided by the thin atmosphere of Mars, but there are plants on Earth (in Death Valley, no less) whose pigmentation blocks out UV light.[8] Actually, UV presents even more evidence for the life search. When ultraviolet sunlight reflects off the Martian atmosphere, it appears on telescopic photographs as a 'blue haze' surrounding the planet. At times, the blue haze vanishes over a portion of Mars, indicating that ultraviolet light is no longer being reflected but instead penetrates to the surface. Shortly after such 'blue clearings,' the surface below will change color, as if the vegetation died under the UV onslaught. Later, the previous coloring returns, as if the vegetation has grown back.[9] Arctic lichens seem the best candidate for a type of plant life that could survive on Mars. The Martian dark regions lack detectable chlorophyll, but so do lichens. And in every other aspect, those regions match the life cycle of lichens. And if there are lichens on Mars, then there is surely microscopic life as well. Such a conclusion is consistent with the telescopic observations. It is also consistent with the actual results of the biological experiments undertaken by the Viking space probe landers in the summer of 1976.
In the first experiment, called the Pyrolitic Release Experiment, a Martian soil sample was placed inside a chamber that had been filled with the external Martian atmosphere. A xenon lamp substituted for outside sunlight. Additionally, carbon dioxide gas was injected into the chamber from a supply aboard the vehicle. This carbon dioxide had been specially prepared back on Earth, so that it contained trace amounts of the radioactive isotope, Carbon 14. After five days, the soil sample was heated to produce a vapor, which was passed through a gas chromatograph tube designed to capture organic molecules (organic molecules themselves are not living, but are produced by biological processes). Once the organics were separated by the tube, a radiation detector sniffed them for the presence of Carbon 14. In theory, if there were any plant-like organisms within the soil, the organisms should have been absorbing the carbon dioxide from the atmosphere and incorporating it into organic molecules, where the trace radioactivity would be detected at the end of the experiment. Therefore, if the detector found only background radiation in the gas chromatograph, that would be a 'No' vote for life. But if there was additional radiation, that would be a 'Yes' vote. The first test-run revealed a radiation count of 96 -- more than five times the background reading of 15 for sterile soil. Somehow, Carbon 14 had indeed migrated from the atmosphere into organic molecules. No known non-biological chemical process could do this in the quantities observed. By the original rules of the experiment, life was the most likely explanation. To rule out non-biological explanations for the chemical changes, however, a 'control run' version of the experiment was conducted, in which a new soil sample was heat-sterilized prior to repeating the same steps as before. In yet another version of the same experiment, the xenon lamp was kept turned off. In both of these variations, the radiation remained at background level. Most plants, of course, cannot survive heat sterilization, nor can they metabolize wholeheartedly without light. Thus, the negative results of these two control runs pointed toward life and away from a possible chemical explanation for the original test run. In a third control run, the soil sample was again reheated, but this time to only 90 degrees Fahrenheit. The positive reading matched what would be expected from most earthly micro-organisms, which can easily survive such temperatures. Thus, the original experiment run and the three control runs most likely indicate that earthlike microorganisms were present in the Martian soil samples. But these were the results of only one of the Viking lander biological experiments. There were still two more to go. In the second experiment, which was called the Gas Exchange Experiment, a soil sample was once again placed in a chamber. A drop of artificial nutrient solution was added. In theory, if there was life within the soil, the microbes would consume the nutrients and produce changes in the balance of several gasses within the atmosphere of the chamber. In agreement with this hypothesis, instrumentation reported that these changes occurred. There was a control run for this experiment as well, involving high-temperature pre-heating of the soil sample. Once again, the chemical reactions ceased, again as if the sample had been biologically sterilized by the heat. So in two experiments with several control runs, the case for life on Mars had passed every test successfully. Onto the third experiment. The third Viking experiment was called the Labeled Release Experiment. Carbon 14 was employed once again, but this time in a liquid nutrient solution that was placed in the soil sample. If there were microbes present in the sample, they would consume the solution, and release carbon dioxide into the atmosphere of the soil analysis chamber, where a radiation detector would spot the Carbon 14 that had migrated during the process. The anticipated high radiation count did indeed occur. But when the sample was heat-sterilized beforehand, it did not. The findings once again pointed toward life. Another variation of this test provided perhaps the most intriguing result of all. In that control run, the sample was heat-sterilized at the relatively low temperature of 122 degrees Fahrenheit. The results now showed that carbon dioxide within the soil was being released and reabsorbed on a twenty-four hour cycle -- which is the length of a Martian day! There is no reason, of course, for a chemical reaction to fluctuate according to the period of planetary rotation. Many microorganisms here on Earth, however, do exactly that, in adaptation to environmental changes that occur from day to night. If life was responsible for the processes taking place within the test chamber, then it was conceivable that the low-temperature heat sterilization had killed off the non-cyclic microorganisms, leaving the cyclic microorganisms to survive and breed. If ordinary chemical reactions were responsible -- well, they couldn't be responsible. Nothing in the chemical world short of the complexity of living microorganisms could produce such results. Thus concluded the three Viking biological experiments. We note that all three of them in all of their control runs unfailingly lead us to the conclusion that microscopic life existed on the surface of Mars. The decades of telescopic observations had been confirmed. Mars was the abode of life. Yet the consensus of the Viking scientific team was that there was no evidence at all for life on Mars! And in time, the message became: No Life.
The shift in attitude did not occur all at once. At the outset, many of the Viking scientists were optimistic. Dr. Herb Klein, head of the biology team, remarked, "It certainly fit the concept that there was some biology going on."[10] Dr. Norman Horowitz, the designer of the Pyrolitic Release Experiment, commented, "It is not easy to point to a nonbiological explanation for the positive results."[11] Illustrating his initial excitement when the data results came in from Mars, Horowitz recounts, "It was amazing. We could hardly believe it."[12] However, severe pessimism was soon to ensue -- thanks to a device known as the Gas Chromatograph/Mass Spectrometer, or GCMS. The GCMS was not part of the official biological test package. It had been included in the lander as part of the geology survey package, as a means of detecting large concentrations of organic molecules in the Martian soil. Organic molecules, it should be stressed, are not 'alive' themselves, nor are they necessarily part of living things. Other processes beside life can also be responsible for the production of organic molecules -- such as fallout from meteors and comets. The GCMS was originally intended to provide data on how these processes had affected the Martian environment; it would do so by measuring the concentration of organic molecules within the Martian soil. The GCMS failed to detect any organic molecules at all, however. While the sensitivity of the instrument was too low to detect the actual presence of living microorganisms, it should have detected the expected amount of organic molecules present in the form of the accumulated corpses of those organisms that had died over many years. But it didn't. Viking scientific team leader Gerald Soffen commented, "All the signs suggest that life exists on Mars, but we can't find any bodies!"[13 ] But . . . the GCMS had never been intended as a biology experiment. It could not even detect living matter, and was only one vote against three. But it swung the scientific consensus. On May 30, 1977, the Martian biology experiments came to an end. The official NASA press release declared: "Biologists have not reached any final conclusion about the presence or absence of life on Mars."[14] While the official statement was ambiguous, the present-day consensus has become: No Life -- It's Exotic Chemistry. Over the years, many scientists have sought to substantiate this. Horowitz has used iron-rich clays to deceive his Pyrolitic Release Experiment into producing a radiation count level identical to that received from Mars.[15] Oxidants have also proved useful in simulating the test results.[16] Although mimicry of the sensitivities to temperature, day-night cycle, and light in the control runs continues to elude years of effort, most of the Viking scientists now believe that the mission test results were due to non-biological chemistry alone.
A century ago, the astronomer Percival Lowell could theorize about canal-building Martians and still be taken seriously. Today he is seen as a crackpot. Carl Sagan checks in around the middle of the road of the Martian-Life spectrum. "I haven't seen anything," he said in 1978, "that makes me go negative on the idea of microbes on Mars; on the contrary, I'd have to say I stand about where I did before."[17] Sagan and other science popularizers leave the question open, but the mainstream view is: Mars is dead, dead, dead. The greatest victim of this scientific consensus is perhaps Dr. Gil Levin. Levin, who designed Viking's Labeled Release Experiment, believes that the presence of life better explains the Viking results than any chemical hypothesis thus far advanced. He has tested life-bearing rocks from Antarctica, gaining a positive result from the Labeled Release Experiment and a negative result from the GCMS on the same sample, proving that the Viking GCMS result is actually irrelevant to the question of life on Mars. This removes the justification for dismissing the Viking biological experiment results. But other scientists won't listen to Levin. Levin's fate was probably cast in stone right from the outset, when his work was pronounced "trivial"[18] by the Nobel-Prize winner and fellow Viking team biologist, Dr. Joshua Lederberger, regarded as the team 'guru.' Lederberger has more recently commented that it is unfortunate that Levin has so badly "misinterpreted"[19] the Viking data. The most vociferous critic of the life hypothesis is Viking biologist Norman Horowitz, the developer of the Pyrolitic Release Experiment. Once, Horowitz says, he too was a believer in a life-bearing Mars. But the sight of those dead craters in the Mariner 4 photographs was a turning point in his life, which he says 'shattered his illusions' and caused him to realize how much 'wishful thinking' had held back the pursuit of legitimate science. Exactly how hope for the discovery of life on Mars had held back exploration of the planet, he doesn't explain. But since his 'moment of truth' he has mounted a vigorous and sometimes antagonistic offensive. Just as Percival Lowell was once absolutely convinced that Mars was the abode of thriving intelligent life, so too Horowitz is absolutely convinced that Mars is dead and always has been dead. Prior to the Viking mission, he declared that there was a "flat zero"[20] chance of finding life on Mars. Although he originally worked briefly with Levin on the Labeled Release experiment, he broke away, later declaring that it was "irrelevant"[21] to the life search. During the Viking mission, he often provided on-the-spot (and doubtlessly annoying) psychoanalysis of the 'wishful thinking' of those who saw the possibility of life in the experiment results. In the 1980s, Horowitz wrote a book on the subject of wishful thinking concerning life on other planets. Entitled To Utopia and Back: The Search for Life in the Solar System, the book relentlessly pounded away at the failure of scientists to disown Percival Lowell's vision of a living Mars. Horowitz speaks of a 'real Mars' thus:
Regarding those who had allegedly misinterpreted the data in their eagerness to make the case for life on Mars, Horowitz offers the following observation:
In Horowitz's mind, those who disagree with him are therefore not only deluded, they are lacking in 'justice' as well, and thus imperiling the 'safety of science.' Horowitz's passion on this matter goes beyond words. In 1986, NASA sponsored a reunion conference for former Viking team scientists, which Levin and Horowitz both attended. Gil Levin gave a slide presentation, in which he restated why he thought that the Viking test results indicated life. Then he went one small step further, showing color pictures from the Viking site at different times of the Martian year, and suggested that the seasonal color changes were compatible with vegetation. This was too much for Horowitz, who angrily confronted him afterward. Levin relates: "We practically had a fistfight. He said, 'You've disgraced me and you've disgraced science!'"[24]
Surface of Mars, as seen from Viking lander camera. But, Horowitz's emotions aside, what of science? What effect did the no-life verdict from the Viking team have on the cause of scientific progress? Gerald Soffen frankly admits that the announced results had a negative impact on space exploration: "It punctured dreams. We did more than say we couldn't find [life]; we said it's probably not there. No question that it influenced the space program."[25] Science writer G. Harry Stine echoes this assessment:
There is a seeming effort to kill interest in the space program and it is ongoing, as Viking alumni scientist Herb Klein demonstrates when he said: "I'm still telling NASA and the Soviets, 'If you want to go back to Mars, don't do any life detection experiments yet.'" This statement was uttered in 1991 -- fifteen years after Viking. He added, "In the last six months we on the inside have succeeded in toning down this eagerness to go back to look for extant life."[27] Klein seems to fear that if the public gets too excited now, they will get too disappointed later, the space budget will be slashed, and science will suffer. Whatever his agenda, truth about the most important question in space science is not at the top. In a similar spirit, Gerald Soffen has : "No one wanted to say 'We found life' and then say 'Sorry.' The whole credibility of science is shot!"[28] Since when did credibility and honesty end up being opposed to one another? Since 1976 and the Viking expedition, apparently. We can compare the public pronouncement to the actual evidence, and conclude which choice was made. Contradictory or not, the idea of obstructing the truth for the sake of science seems to have come naturally to those scientists involved in the study of life on Mars. At the core, something must have caused scientists to develop an ideology in which preservation of the reputation of science is more important than the pursuit of truth. And whatever this core philosophy is, apparently the discovery of life on Mars is in direct conflict with it. That is why they were blind -- and remain defiantly so to this day. On August 7, 1996, President Bill Clinton announced that an antarctic meteorite, known as ALH84001, had been deduced by NASA scientists as having come from Mars -- and contained structures that the scientists thought might be fossils of microscopic life that lived on the planet billions of years ago.[29] While the declaration galvanized the general public, it did not significantly challenge the Viking scientific team viewpoint that Mars today is a dead world. Life briefly evolved on Mars, so what? It never advanced farther than microscopic organisms, and then it died out -- and billions of years ago. Rest easy tonight. Meanwhile, Mars is waiting for a bolder generation -- one that will objectively look at the evidence, one that will not discount truth in favor of reputation, one that will not be afraid to let the cherished theories crash. For those who are ready, the adventure awaits.
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Pyrolytic Release Experiment 
