Is There Life on Mars

I cannot say I believe that there is life out there. All I can say is that there are a number of reasons to think it is possible and that we have at our command the means of finding out. Those two things being the case, I would be very ashamed of my civilization if we did not try to find out.

--Astronomer Carl Sagan

FROM the first time he looked into the heavens and sensed that there were worlds beyond his own, man has sought to answer a haunting question: Are we alone in the universe? Although he has worked out many rationales to justify costly space programs, man's prime motivation for launching his rockets is his determination to learn if there really is extraterrestrial life. Last week that determination seemed more intense than ever.

Convinced by the findings of the Apollo missions that the moon is lifeless, the earth's two superpowers were concentrating on the next target of opportunity: Mars. A pair of spacecraft, America's Mariner 9 and Russia's Mars 2, were in orbit around the Red Planet, seeking out conditions and features that might support life and radioing their findings back to earth across more than 90 million miles of space. A capsule ejected from Mars 2 lay on the Martian surface, possibly equipped with instruments that could sample the soil and the atmosphere and detect the presence of life. And a second Mars-bound Soviet spacecraft was closing in; it too was presumed to carry a capsule capable of making a soft landing.

At the same time, scientists were readying Pioneer F, a spacecraft that will take off in February on a 600-to 700-day journey to Jupiter, which could harbor life--or the precursors of life --in its atmosphere. In 1973, if all goes well, Pioneer will send back pictures and information while it flies by the largest of the solar system's nine planets. Mars is also in for more scrutiny. The Soviet Union will probably launch Mars probes in both 1973 and 1975, and two U.S. Viking spacecraft are scheduled to land life detectors on the Martian surface in 1976.

Birth of Exobiology

Such vast expenditures of energy and resources are contributing to the growth of an entirely new science called exobiology (from the Greek exo, or out of), which has come into being in the past decade and is dedicated specifically to the study of extraterrestrial life. Paleontologist George Gaylord Simpson has sardonically called exobiology a science "that has yet to demonstrate that its subject matter exists." But in laboratories, at giant radio observatories and at esoteric symposiums, some of the world's keenest intellects have begun to focus on the new discipline.

In September, for example, dozens of eminent scientists--including two Nobel laureates--gathered at the Byurakan Astrophysical Observatory in Soviet Armenia under the auspices of the Soviet and U.S. Academies of Science to ponder a mind-boggling proposition: Should man try to monitor the messages of other worlds? The answer was a resounding yes. Russian, U.S., Czech. Hungarian and British delegates united to support an unusually cooperative proposal: "It seems to us appropriate that the search for extraterrestrial intelligence should be made by representatives of the whole of mankind."

In the heady friendliness of the conference, the Russians also saw fit to reveal that they are conducting two continuing searches for messages from space. A 50-ft. radio telescope is "listening" to the emanations from 50 relatively nearby stars, one at a time, in the hope of picking up an intelligent signal; and radio observatories in four different locations are trying to detect short, intense bursts of electromagnetic energy that might be transmitted into space by the technological products of an advanced civilization.

At a similar conference last summer at NASA's Ames Research Center near San Francisco, one of the chief exobiology research centers in the U.S., participants discussed the feasibility of launching Project Cyclops. The ambitious enterprise, which might cost as much as a billion dollars, would involve building three vast arrays of radio telescopes to conduct a more effective search for messages from the stars.

In their discussions of extraterrestrial life, most exobiologists suggest that in all probability the universe is teeming with intelligent beings. Most are now convinced that there is no intelligent life or technological civilization on the other eight planets of the solar system. If intelligent, technological races inhabit any of the other planets or their moons, so the argument runs, man would likely have heard from them--or have been visited by them--long ago. But that reasoning in no way diminishes the intense interest that most scientists feel about the faintest possibility of finding any form of life--or clues that it once existed--on the earth's planetary neighbors.

A Jarring Sight

For centuries, scientists have concentrated on Mars as the most probable habitat of extraterrestrial life. After cloud-covered Venus, Mars is the planet closest and most visible to earth. Through a telescope, its earthlike polar caps can easily be seen, receding and advancing as the seasons change. Another seasonal variation, a wave of darkening that appeared to move out from the polar regions in the spring, once led earthbound observers to believe that the melting icecaps released water that in turn promoted the growth of vegetation.

Many such illusions were shattered in the 1960s when Mariner spacecraft gave man his first closeup look at the Red Planet. It was a jarring sight: a bleak moonlike landscape pockmarked by craters, with no seas and no obvious vegetation. The Mariner instruments and telescopic observations from earth revealed that the Martian atmosphere was less than 1% as thick as the earth's and consisted largely of carbon dioxide with slight traces of water vapor. In addition, there was no evidence of any shielding ozone in the atmosphere, which meant that the sun's searing ultraviolet radiation, deadly to earth life, poured continuously onto the surface. Finally, the Mariners detected no magnetic field around Mars, indicating that the planet did not have a molten-iron core like the earth's. That finding seemed to suggest that Mars was never hot enough to melt and differentiate, a process in which the lighter elements vital to earth life rise to the surface and harden to form a crust.

For laymen and some scientists, these discoveries dealt a crushing blow to the possibility of finding life on Mars. But Cornell University Astronomer Carl Sagan, exobiology's most energetic and articulate spokesman, was less easily discouraged. To prove that Mariner flybys would have difficulty detecting any signs of life on Mars from a distance of thousands of miles, Sagan sifted through pictures of the earth taken by weather satellites and discovered that only one shot in a thousand showed evidence of man's presence. He presented his conclusions in a provocative paper that in effect asked: Is there life on earth? Later, Sagan puckishly noted that Martians visiting the earth might believe that automobiles were the dominant form of terrestrial life; the environment is altered to fit their needs and they act much like living beings by moving, eating and excreting.

Exobiologists do not insist that life exists on Mars; they argue only that the harsh conditions on the planet do not necessarily preclude life. On earth, they point out, organisms have managed to thrive in environments ranging from the icy wastes of Antarctica to the windblown summits of high mountains to the enormous pressures of deep-sea trenches. Adds University of Maryland Exobiologist Cyril Ponnamperuma: "We have even found life in boiling hot springs and strong acids."

To buttress their case, exobiologists have exposed microorganisms to simulated Martian environments (carbon dioxide, extreme cold, small amounts of water) in so-called "Mars jars." Some of the bugs readily adapted to the Martian conditions. For this reason, Western scientists were all the more concerned last week that the Russian lander might, if not completely sterilized, introduce earthly life forms to Mars.

Scenarios for Survival

Exobiologists have suggested a number of scenarios for the survival of Martian life. Sagan, for instance, theorizes that Mars may now be experiencing an ice age. As he explains it, the planet's northern hemisphere does not now receive the maximum possible dose of solar radiation because the Martian north pole is tilted toward the sun only when the planet is farthest from it. Yet in about 10,000 to 12,000 years, because of the slow precession of Mars (a wobbling of the planet as it rotates through space), the north pole will be tilted so that it receives more solar radiation during the planet's close approach to the sun. The increased radiation would heat up the northern icecap, release large amounts of trapped water into the atmosphere and make enough water available to stir up any lazy creatures that might have hibernated through the long Martian winter. Impossible? Perhaps, says Sagan, but he adds that those who criticize such speculations do so only because of their "chauvinistic" earthbound outlook.

That chauvinism is displayed time and again, say exobiologists, by those who cannot conceive the possibility of life without water (which Sagan calls "liquid-water chauvinism"), without oxygen ("oxygen chauvinism") or in the presence of intense ultraviolet radiation ("ultraviolet chauvinism"). Yet life can indeed develop under conditions radically different from those on earth. It did, for example, evolve during untold eons on earth when there was no oxygen in the atmosphere. To those primitive forms of life, in fact, oxygen would have been a poisonous gas. Thus instead of requiring oxygen, Martian organisms, like some terrestrial bacteria, might thrive in a carbon dioxide environment. To obtain water if they need it, Martian organisms may have evolved mechanisms to unlock the supply chemically bound into the rocks of their bleak planet. If Martian creatures found intense ultraviolet radiation unbearable, Sagan speculates, they may have developed tough silicate shells that would protect them from it. The reason that Mars does not reflect back much ultraviolet radiation, he says whimsically, may be that all those turtle-like creatures are absorbing it.

That any Martian creatures, turtle-like or otherwise, will be discovered during the current Mars missions seems highly unlikely. Mariner 9, mapping the planet with its twin TV cameras and using ultraviolet and infra-red sensors to probe the surface and the atmosphere, will never come close enough in its far-ranging 860-mile by 10,600-mile orbit to photograph any life forms. Although the Russians have announced that their Mars 2 lander carried a Soviet pennant to the Martian surface, they have been silent about the performance of any life detectors or other instruments it might have carried.

Nonetheless, Mariner 9 has already added important new findings to man's knowledge of Mars. Near the south pole, one of the few areas where Mariner's cameras have been able to peer through the huge dust storm that still obscures much of the planet, the surface is also remarkably smooth, leading some scientists to theorize that the region was scoured clean by glaciers as the polar cap grew during Martian winters and then receded again. If glaciers were indeed responsible, their presence would indicate that there is more water in the polar cap (which is composed largely of frozen carbon dioxide, or dry ice) than anyone had supposed. Mariner has also discovered four craters that the U.S. Geological Survey's Harold Masursky and others believe are extinct volcanoes, one of them relatively young. Exobiologists are excited by the finding because they think that most of the amino-acid-building gases in the earth's primordial atmosphere were belched forth by volcanoes.

Turning its cameras away from the Martian surface. Mariner provided a bonus for scientists at Caltech's Jet Propulsion Laboratory: the first closeup pictures of the two tiny moonlets of Mars. Deimos and Phobos. Sharpened and clarified by computers, the photographs finally laid to rest an enticing theory put forth a few years ago by Soviet Astrophysicist I.S. Shklovskii. who said that the apparent behavior of Phobos in orbit meant that it could be hollow. That in turn suggested to Shklovskii that the moonlet might be an artificial satellite, lofted into orbit by a long-extinct Martian civilization. Instead, Mariner's photos have revealed that both moonlets are irregular-shaped hunks of rock, pockmarked with craters.

Whether or not Mars is eventually proved lifeless, never-say-die exobiologists are looking forward to investigating Jupiter and perhaps taking another look at Venus for signs of living organisms.

Although few expect to find life on the face of either planet (atmospheric pressure on Jupiter's still-unfathomed surface would probably be too high, and temperatures at the surface of Venus are more than 800DEG F., hot enough to melt lead) there is a possibility that organisms may have evolved at levels of the atmospheres where temperatures and pressures are moderate. The irrepressible Sagan has speculated that one form of Jovian life might be large, ballasted, gasbag-like creatures that swallow up organic matter as they float through the thick Jovian atmosphere like plankton-eating whales. But even the failure to discover biological activity on the other planets circling the sun will not discourage the life seekers. They will then turn their full attention to the stars. For they are certain that given the right conditions, the creation of life anywhere in the universe is more the rule than a miraculous accident.

Innumerable Suns

Even before man had scientific facts to back his convictions, he was confident about the existence of extraterrestrial life. "To consider the earth as the only populated world in infinite space," said the 4th century B.C. Epicurean Philosopher Metrodoros, "is as absurd as to assert that in an entire field sown with millet only one grain will grow."

In the Middle Ages, when it was dangerous to question Christian dogma, which held that the earth was the center of the universe and that other worlds were lifeless, the Polish astronomer Copernicus and his followers thought otherwise. Although he prudently did not publish his epic work On the Revolution of Heavenly Bodies until he lay on his deathbed, Copernicus dealt the earth-centered universe of Ptolemy its final blow. After years of observations, he concluded it was the sun--and not the earth--that occupied center stage; the earth, he said, was simply one of several planets that spun around the parent sun. A zealous disciple, the Dominican monk Giordano Bruno, added an even more shattering idea. "Innumerable suns exist," proclaimed Bruno. "Innumerable earths revolve about these suns in a manner similar to the way the seven [then known] planets revolve around our sun. Living beings inhabit these worlds." Although Bruno was burned at the stake in 1600 as a heretic, his views lived on.

In fact, after the newly invented telescope showed man that the planets were not simply flecks of light, it became quite fashionable to regard all of them as inhabited. The 18th century astronomer Johann Elert Bode, author of Bode's Law (each planet is roughly twice as far from the sun as the previous one), contended that the same mathematical proportions held for the spirituality of their inhabitants. Thus, by Bode's reckoning, Martians, on the fourth planet from the sun, were considerably more spiritual than the people on the third (earth).

In 1877, the Italian astronomer Giovanni Virginio Schiaparelli (an uncle of the present-day Paris couturiere) reported actually observing canali linking dark areas on Mars. Although the Italian word can simply mean channels or grooves, it was promptly translated into English as canals, which suggested that they were artificially made. That inspired an erstwhile American diplomat named Percival Lowell (of the Boston Lowells) to take up astronomy and establish an observatory near dry, cloudless Flagstaff, Ariz., principally to study Mars. Lowell spotted hundreds of "canals" on the Martian surface and contributed the theory that they were the work of an advanced civilization. Belief in intelligent life on Mars was dramatized by H.G. Wells in his novel The War of the Worlds and carried into contemporary times by another Welles named Orson, whose 1938 radio broadcast of the novel caused widespread panic in the U.S.

In their persistent belief that extraterrestrial organisms exist, modern scientists are supported by laboratory experiments that have already brought man close to understanding the secrets of the origin of life. According to some theories, that process began shortly after the formation of the earth some 4.6 billion years ago. The primordial planet was still enveloped in a thick atmosphere of ammonia, methane, hydrogen and water vapor. Perhaps because of the sun's ultraviolet radiation, or lightning discharges in the earth's turbulent atmosphere, or even the heat from the volcanoes that were erupting all over the face of the young, seething planet, some of the atmospheric molecules broke up and reunited in different combinations. After these molecules were washed into the earth's seas they formed amino acids, organic compounds that are the building blocks of protein and of life. Other reactions in this "soup" formed the forerunner chemicals of nucleic acids, which in turn are the building blocks of DNA, the master molecule that directs the production of protein in living cells.

Genesis Molecule

Finally, after millions of years and countless interactions, a long molecule was born that had an extraordinary capability: it could replicate, probably by breaking into sections that attracted other chemicals that in turn became duplicates of the original molecules. With the emergence of these genesis molecules, biological evolution was on its way.

A now classic experiment, performed in 1953 at the University of Chicago by a young graduate student named Stanley Miller, suggests that the theory is correct. Following a scheme proposed by Nobel Laureate Chemist Harold Urey, Miller managed to produce amino acids and other organic compounds by sending electrical discharges through a mixture of gases that simulated the earth's early atmosphere. Since then, a host of other researchers have repeated the experiment with different energy sources--ultraviolet rays, heat lamps and even shock waves. Taking the process through one more giant chemical step, Chemist Sidney Fox of Florida's University of Miami has succeeded in linking up test-tube amino acids into what he calls "proteinoids." These are tiny protein fragments that tend to form themselves into bacteria-sized spheres. In equally dramatic experiments, Ponnamperuma and Biochemist Juan Oro at the University of Houston have shown that it is also possible, in laboratory simulations of the early conditions on earth, to make several of the chemical building blocks of nucleic acids.

There is increasing evidence that similar chemical combinations take place in outer space. Of the thousands of meteorites that bombard the earth each year, about 2% contain organic, or carbon-rich, compounds. On several occasions, researchers claimed that some of these meteorites--called carbonaceous chondrites--contained amino acids and even fossilized remnants of microscopic extraterrestrial life. But most scientists have contended that the amino acids or living debris was picked up by the porous meteorites either as they plunged through the earth's atmosphere or later in the laboratory.

The whole argument was dramatically reopened last year by the Ceylonese-born Ponnamperuma, who identified 17 different amino acids in a newly fallen Australian meteorite. Ponnamperuma conceded that e a thumbprint on a laboratory beaker could have introduced the acids into his test samples, but he presented evidence that seemed to rule out the possibility. Although amino acids can be assembled in two ways--one a mirror image of the other--most of those found in terrestrial life have a left-handed configuration; that is, polarized light waves passed through them are rotated slightly to the left. Yet, when Ponnamperuma tallied up the meteorite's amino acids, he found an almost equal distribution of left-and right-handed molecules. That, he felt, was a clear sign that they had come from space.

Swirling Clouds

There is growing evidence that the basic chemicals of life can be found beyond the solar system. In 1968, a team of scientists from the University of California at Berkeley pointed a radio telescope toward the center of the Milky Way galaxy, the island of stars in which the sun is located. To their great satisfaction, the big electronic ear picked up emissions that could only be given off by ammonia molecules (bombarded by radiation, molecules emit characteristic signals that can be used like fingerprints for identification). For the first time, complete, chemically stable molecules had been found in the swirling clouds of gases that occupy the enormous spaces between the stars.

Since that discovery, about two dozen molecules, including carbon monoxide, formaldehyde, ethyl alcohol and water, have been identified in distant space.

The discovery of these far-off molecules, many of which are essential to life, indicates that the same chemical concatenations that led to life on earth may be under way throughout the universe. Says Carl Sagan: "The building blocks of life are lying around everywhere."

Even so, life elsewhere in the universe might resemble nothing on earth. It would almost certainly be molded by different environments and possibly by different chemistries. Says Sagan: "If we started the earth all over again, even with the same physical conditions, and just let random factors operate, we would never get anything remotely resembling human beings. There are just too many accidents in our evolutionary past for things closely resembling human beings to arise anywhere else."

Although their thinking may well reflect planetary chauvinism, most scientists believe that life, whatever its form, can begin only on a planet or one of its moons; it is inconceivable to them that it can evolve among the molecules floating in space or within the nuclear fires of stars. But are there any planets outside the solar system? The capability of detecting a planet in orbit around even the sun's nearest stellar neighbor is beyond the power of the largest optical telescopes, but many astronomers are convinced that there are billions of planets in the observable universe. The sun, they note, is an ordinary star in an island of 100 billion stars, the Milky Way galaxy. The Milky Way, in turn, is just one of billions of galaxies in the universe. Thus the laws of mathematical probability would weigh heavily against the notion that the sun is the only star with a planetary system. Moreover, the more recent theories of stellar evolution pre dict that the formation of planets around ordinary stars like the sun is more the rule than the exception.

Astronomers have even more direct evidence that there are distant, unseen planets. Analyzing a wiggle in the path of Barnard's star, one of the sun's nearest neighbors,*they have concluded that two planets about the size of Jupiter and Saturn are orbiting the star and exerting a gravitational pull that affects its course. The observation raises the possibility that other smaller planets with less noticeable gravitational pull are also circling Barnard's star, and it helps support one common estimate by astronomers that there may be at least 50 billion planets in the Milky Way alone.

Not all of these planets can support life. To do so, they must be orbiting a star that shines with steady intensity for billions of years and must occupy what NASA Astrophysicist Su-Shu Huang called the star's habitable zone --the region in space where the amount of solar radiation is neither too intense nor too weak for life. Taking these requirements into account and considering the rate of new star formation (about one per year in the Milky Way), the percentage of stars that have planets (about half), and other factors, the scientists attending the September meeting in Armenia concluded that there are now 100,000 to 1,000,000 technological civilizations in the Milky Way. They are an average of a few hundred light-years apart, and each one is capable of transmitting radio messages.

That number, the scientists agreed, could vary widely, depending on the length of time that a race could survive as a technological society. Pessimists in the group estimated that a civilization might survive as little as 40 or 50 years after it developed the capacity to transmit radio messages; it would soon destroy itself in a nuclear holocaust or pollute itself to death. With that short a life span, the number of technological civilizations existing concurrently within the galaxy would be quite small, the average distance between them immense, and the possibility of an exchange of messages sharply reduced.

In any event, space travel as man knows it would be out of the question for contacting a civilization in another solar system. If an astronaut were sent off in a space ship traveling at rocket speeds of five miles per second, for example, it would take him at least 80,000 years to reach the nearby star, Proxima Centauri, which is 4.3 light-years away; more distant stars might keep him en route for hundreds of thousands, millions or billions of years.

But if technological civilizations are capable of surviving hundreds of thousands of years, as the optimists at the conference suggested, the number thriving at any one time would be much greater, the average distance between them reduced and the possibility of communication--at least by radio--greatly increased. Says Astrophysicist A.G.W. Cameron of New York's Yeshiva University: "We know that our species has managed to live 26 years since the development of the Abomb. We want to know if it is going to live 100, 1,000, 1,000,000 or 1 billion years. The whole argument about communication hinges on the longevity of a species."

Man, for example, has been inadvertently sending strong signals into space for about 15 years by using military radar and UHF communication devices. If the nearest technological race is 20 light-years away, for instance, the terrestrial signals will reach it in 1976. If that distant race immediately composes a message and sends it back, it will not reach the earth until 1996. Will atomic-age man still be here to receive it?

There are other formidable problems in communicating with an alien race. At what frequency would a civilization listen for and transmit messages? Many scientists have proposed the 21-cm. band, which is the wave length of emissions from the hydrogen atom, the most abundant element in the universe. Another hurdle might well be the choice of a language that would be universally understood by intelligent beings (see diagram, page 56). Also, because man has so recently entered a technological state, any civilization capable of receiving earthly signs might be far more sophisticated. Would it bother to reply? Possibly not, according to Sagan, because the alien race might find men as inferior as men find ants. "Would we bother teaching the alphabet to the ants?" he asks.

On several occasions in the past decade, radio astronomers have been startled to receive signals that seemed to signify an extraterrestrial intelligence. By 1960, when scientists led by Frank Drake in an operation called Project Ozma used the radio telescope at Green Bank, W. Va., in an attempt to pick up signals from nearby stars, they detected regular pulses that were later presumed to be emanating from a secret U.S. radar experiment. In the mid-1960s, a Russian astronomer detected varying signals from a mysteri ous radio source; Tass breathlessly reported that the signals were a beacon from a supercivilization. The source was later identified as a distant, starlike quasar. When Cambridge Astronomer Anthony Hewish and his assistant Jocelyn Bell in 1967 recorded blips coming from space at precise intervals, they playfully named the sources LGMs (for Little Green Men) on the chance that they had detected the beacon of an advanced civilization. The LGMs were later named pulsars and recently identified as natural phenomena: the long-sought neutron stars. Despite man's failure to pick up any interstellar communications, however, the entire galaxy could be filled with chatter between advanced civilizations, transmitted by a technique still undiscovered on earth. Says Carl Sagan: "We may be very much like the inhabitants of an isolated valley in New Guinea who communicate with villages in the next valley by drum and runner but have no idea that there is a vast international radio traffic going around them, over them and through them."

God's Quarantine

If a signal from another planet is ever received and deciphered, it would surely have an immeasurable impact on man. In one brief burst of information it would expand his horizons into infinity. In the process it would force him to re-examine some ancient questions. With his long heritage of Judeo-Christian culture, could Western man still be certain of his superior status in a God-created universe? Orthodox Christian theologians admit no doubts. There is, they insist, only one sovereign Lord of all creation, and he created man in his image. C.S. Lewis, prolific Protestant author and theologian, was not so sure. Faced with the discovery of rational, intelligent creatures elsewhere in space, he asked, how could mankind be so arrogant as to think itself uniquely favored by God? What worried Lewis was that earthly man might some day send his missionaries out to other planets, pressing salvation upon creatures who have no need for it, denouncing as sin differences of behavior that God had created and blessed. Thus the witty skeptic proposed that "the vast astronomical distances may be God's quarantine precautions. They prevent the infection of a fallen species from spreading."

Scientists believe the missionaries--or at least their message--would travel in the other direction, spreading not infection but hope. Any civilization capable of communicating with earth from another planet would unquestionably be older than man's. It would have long since mastered the problems that now plague the earth; pollution, overpopulation and the ever-present threat of war would surely be a part of its past. And if it had learned to control the awesome power of the technology that it surely must possess, perhaps it would teach that secret of survival to man.

*Six lightyears, or 36 trillion miles away.

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