Life on Mars? On July 14 we could know
Mariner IV is morethan just another spacecraft. As it nears journey’s end, sensitive instruments and a TV camera stand ready to scan the enigmatic Red Planet What they find could unlock the deepest mystery of the universe: the origin of life itself
N. J. BERRILL
LAST NOVEMBER the spacecraft Mariner IV was launched on a course that would intercept the planet Mars on July 14 of this year. On that day, if all has gone well, the spacecraft is expected to fly by Mars at a distance of about five thousand miles from its surface and take twenty-one close-up portraits, one every fortyeight seconds, together with magnetic readings. Then, curving behind Mars under the pull Martian gravity, radio signals will be beamed to the earth through the Martian atmosphere to measure the atmospheric density. Mariner IV, with its 138,000 delicate parts, will have made a 325-million-mile trip in 228 days, keeping to its course by means of its electronic eye fixed on Canopus as its guiding star. Unlike Mariner II which swung toward the sun after passing close by Venus, Mariner IV will careen off into the outer darkness of the solar system after scrutinizing Mars. Both Mariners have been sent off with the same general end in view, as the first steps in the search for life, any sort of life, beyond the limits of the earth.
The possibility of life existing on b planets has attracted much speculation dur the past. They are the nearest planets to earth, except for the obviously barren mo Venus, almost exactly the same size as earth and enveloped in a dense protect cloud cover that hides all sight of the surfa held mystery and the most promise u Mariner f] and some refined earth-ba astronomy recently dashed our hopes. MÍ with only half the diameter of the earth, is too clear, so much so that surface markii can be seen which the American astronorr I ercival Lowell, around the turn of the centi interpreted as vegetation bordering canals mí by intelligent inhabitants of a dying piar struggling to keep alive by a planetwide syst of irrigation from the water of melting snc caps. Fantasies such as this have long sir gone by the way and both Mars and Ver are now regarded as pretty grim environme lor anything alive, that of Venus apparen impossibly so, that of Mars perhaps margina
permissive. Why. then, all the fuss? For these projects are enormously expensive in every way, and they are but the beginning. A recent scientific editorial states that for several years numerous prominent scientists, singly and in concert, have voiced the belief that the impending search for extraterrestrial life may produce the grandest experiment in science, perhaps the most momentous event in the history of man. The discovery of living things on another planet would give us our first perspective of that presently unique and baffling enigma, life. Scientists, philosophers, theologians, and the man in the street would find the information of prime importance in testing and shaping their theories and beliefs. The results would be felt throughout the society of man and would have a profound, continuing influence.
The basic question is the origin, or origination of life. Most religions, primitive or advanced, are concerned with this question, and it is one that looms large in present-day biology and biochemistry. How
U.S. scientists deem life on Mars likely
WASHINGTON — A panel of thirty-six scientists, convened at the U. S. government’s request, has concluded that the possibility of life on Mars is strong enough to justify an immediate start on plans to explore the planet. “The biological exploration of Mars is a scientific undertaking of the greatest validity,” the panel reported. “We wish to test the hypothesis that the origin of life is a probable event in the evolution of all planetary environments whose histories resemble ours. (Among) our specific aims are: determination of whether or not life is or has been present on Mars; and characterization of that life, if present.”
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Are we special or
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did life first begin on the earth? Many other questions follow but this is primary. The current scientific theory is that life first came into being on earth as the result of entirely natural conditions prevailing when the earth was very young, some three or four billion years ago, as the result of solar radiation acting on the various gases and watery solutions present at the time. Laboratory experiments already give strong support to this view, but the real proof would be the finding of some forms of life on a planet other than the earth. Then we would know that the earth is not unique in having life, that we are neither a special creation nor an accidental freak of no significance in the universe, but that wherever planets exist and circumstances are suitable, life has evolved or will yet evolve. And to settle this matter we do not need to find advanced forms of life such as we know on earth, let alone something or someone intelligent such as we suppose ourselves to be. Even the simplest living things, as lowly as bacteria, would be sufficient, always supposing the “find” is not something we have inadvertently introduced ourselves in landing instruments improperly sterilized first.
This question of life involves the solar system as a whole, for it is truly a system on its own and it is so far isolated from any other that our only prospects of investigation are here. We need to know all we can about all the planets before we can fully appreciate why the earth, as is almost certainly the case, is blessed with a richness of life above all others. Already we think we know, but a visit to Mars would make all the difference between thinking and knowing.
The presence of water in liquid form is of first importance. All life is very watery — ninety-eight percent for a jellyfish, sixty-eight percent for a man and much higher than that if the bones are omitted. And the unique properties of water are such that no biologist or chemist has yet conceived how any other substance could possibly be substituted for it in living matter. Consequently, life seems possible only within the temperature range between steam and ice. which puts a crimp on planetary possibilities within this or any other solar system.
Too near the sun. water exists as vapor and too readily escapes into space. Too far from the sun, it persists as crystalline ice. Only in a relatively narrow belt at some distance from the sun can water be water with all its uniqueness and liquidity, and such a belt will itself have an inner and an outer margin where water barely makes the grade, with the happy mean somewhere in between. This happy mean is where we are. whereas Venus and Mars lie close to the inner and outer limits. The moon, obviously as well placed as the earth, is so small a planet and therefore its gravitational pull is so puny, that whatever surface water and atmosphere it may have originally possessed have long since been lost to space. Venus, as massive as the earth, might well have had oceans in addition to its dense atmosphere. but indirect evidence indicates that it has a hard, hot. waterless surface hostile to life and, although this may not be the last word, it is enough to direct our interest elsewhere.
Elsewhere means Mars, for the red planet, smaller than the earth but much larger than the moon, has both surface water and atmosphere, though none too much of either. However this may be. Mars represents the remaining hope for discovering any sort of extraterrestrial life within the solar system, for all the giant planets with their orbits farther out than Mars have deeply frozen atmospheres.
Consequently an “on to Mars” policy has been rapidly gaining ground during the past few years. Even so. the launching of Mariner IV toward Mars late in 1964 came almost as a surprise. For complications had appeared. The original plan adopted by the National Aeronautics And Space Administration was for a tentative launch date for a Mars lander in 1964, a lander being an actual landing of instruments on the planet’s surface by means of parachutes released from the space craft. Experimenters working on life - detection devices were asked to schedule their hardware development accordingly; 1964 was a critical date for launching because only once in every two years does the earth pass close enough to Mars for such a project to be feasible. It soon became apparent however that the vehicle designed to carry the instruments had propulsive difficulties and the 1964 effort became impossible.
Sights were shifted to 1966. the next launch “window.” Progress was made toward producing the required thrust and the 1966 prospect seemed good, until some startling new data was obtained by earth - based instruments concerning the Mars atmosphere. Previously the atmosphere at the surface had been estimated to be about one tenth that of the earth, or roughly the density of the earth’s atmosphere at an altitude twice the height of Mount Everest. The new spectroscopic evaluation of the density of the Mars’ atmosphere is so much lower that the proposed parachute landing of the instrument capsule would not be possible, retro-rockets would have to be used and their added weight might reduce the payload to the marginal point. There has also been new data concerning the temperature of Mars, indicating a much higher temperature than had been expected. This may. however, be radiation associated with the magnetic field, if there is one. and not an indication of actual heat.
All of this adds up to the reason why Mariner IV was shot off toward Mars late in 1964. almost at the last possible moment. Mariner III, launched a few weeks earlier but off its course, had been part of the same venture If Mariner IV had also failed. f no further attempt could have been made until 1966. It had become essential to know for certain whether the new estimates of the Martian atmospheric density and temperature were what they seemed to be or not. Without confirmation one way or the other, the planning of the Mars' program could not proceed. Accordingly Mariner IV has been sent on a flyby mission similar to the one sent to Venus, with the primary purpose of determining at close hand just how' dense the atmosphere of Mars may be and whether or not the planet has a protective magnetic field like the earth’s. Any close-up pictures of the planet's surface will of course also be of inestimable value.
What can be expected of Mars? Certainly not very much in the way ol life, but however little it may be, as long as there is something, it will be enough if scientists ever succeed in analyzing it. The prospect of finding some sort of Martian life is fair.
To begin with, certain similarities with the earth are suggestive, particularly the seasonal expansion and shrinking of the north and south white
polar caps. They are known to be frozen water, but w'hether as ice. snow or hoarfrost is uncertain. In any case they are thin and the seasonal melting, especially in the south, is both rapid and extensive. It is possible that they change to water vapor directly, without passing through a melted, or liquid state. Even more suggestive are the dark and orange areas that lie in the middle latitudes between the two polar caps, for they also undergo verymarked seasonal change. It is signifi-
cant that the color change begins in spring next to the polar cap and progresses toward the equator, indicating a close dependence of the color change upon the melting of the polar cap. During the spring of the southern hemisphere the color change continues over the equator into the northern hemisphere. Occasionally new areas appear and old ones vanish. The natural explanation would seem to be that the areas that darken with the apparent spread of moisture represent vege-
tation of some sort, although nonliving. chemical changes have also been suggested.
One of the most important questions concerning Mars as a possible abode of life is not so much whether water is present, for that seems certain, but how' much water is there. Estimations of the amount of water vapor made from the Swiss observatory at the top of the Jungfrau and from high-altitude balloons, indicate that there is barely enough to cover
the surface of Mars with a film of moisture, suggesting that the extent of free water evaporating at the surface is not great. But it says nothing of the possibility, of ice. One Russian astronomer thinks that the canal-like markings may actually be great fissures in a thick layer of ice covering the whole planet, most of which however is covered with dust and sand.
Photographs taken by Mariner IV may show a great deal concerning the planet’s surface, though it should be realized that so-called close-up pictures taken from a distance of five thousand miles are actually as far as Montreal is from Stockholm. However, details as small as two miles across will appear, so that mountains, craters, ice fields, and lakes should show up if present. When Mariner IV was launched, Mars was far ahead of the earth but traveling more slowly on the outside track. By the time the pictures are being taken, the earth will be about 134 million miles ahead of Mars and the pictures will have to be televised to the earth through that distance. This will require power and the necessary amount will be gathered from sunlight hy solar cells and the pictures transmitted one by one at intervals during the week following the actual fly-by.
Whether or not Mars has a magnetic field is important in several ways. The question has strong bearing on the relationship of a planetary magnetic field to a planet’s rotation about its axis and the presence of a fluid metallic core, and the answer will do much to confirm or to upset present views concerning the structure of the earth. Apart from this and with more direct bearing on the suitability of Mars as an abode of life is the role played by a planet’s magnetic field in deflecting cosmic rays pouring out from the sun. If it were not for the earth’s magnetic field, especially the so-called Van Allen belts far out beyond the atmosphere, intense rays deadly to life would penetrate to the earth’s surface. Venus and the moon do not have a magnetic field, nor do they rotate, at least significantly, whereas the largest of all the planets, Jupiter, not only rotates more than twice as fast as the earth but has a magnetic field powerful enough even at such an enormous distance to be a disturbing source of radio interference. Mars is fully expected to belong to the magnetic company, but we do need to be sure.
Questions concerning the nature of the Martian atmosphere, other than the matter of density, may remain unsettled. All that can be said at present is that the proportion of carbon dioxide is higher than in the terrestrial atmosphere, that water vapor is much lower, and that no oxygen has been detected. It is considered likely that nitrogen is the predominant atmospheric gas, as it is here. If such is the general case, however, there is still no reason to suppose that life cannot exist, although it would necessarily be different from what we know here.
If the seasonal color changes are in any way connected with the presence of living organisms, we at least have some inkling of what to expect. To begin with, the nature of Martian organisms must be able to account for a number of the planetary features
already observed. They must be visible or must form visible colonies that cover the ground rather extensively. They must account for the color and the observed color changes, and they must account for the changes in size and shape of the dark areas, and be able to grow and migrate fairly rapidly. All under the seemingly unfavorable Martian circumstances. That this should be possible is not to expect too much, for even on the earth many organisms live and thrive in some amazing places. Bacteria grow and multiply in the sands of the desert and nigh in the atmosphere, while some algae live in hot springs or in mountain snowbanks. Other organisms thrive in vinegar, in tanks of gasoline and phenol, and a great many kinds of marine creatures live in the dark cold of the oceanic abyss. Yet none of these could account for what we can see on Mars. Lichens have been suggested as the type of vegetation we could expect to find on Mars, but lichens themselves are combinations of algae and fungus and, although tough and content with a minimum of oxygen and water, are so slow-growing as to be disqualified.
Manned landing necessary
Unless the shifting color changes have nothing to do with the presence of life on Mars, some sort of vegetation must exist. The apparent absence of free oxygen in the atmosphere indicates that if photosynthesis by plantlike organisms takes place at all, it must be accomplished by something other than green chlorophyll such as we are familiar with, for the oxygen in our own atmosphere is considered to be entirely or almost entirely a byproduct of photosynthetic activity. Oxygen, however, may be present but in too low a concentration to be detected by examining the reflected light
from Mars by peeking at it through the earth's own oxygen-laden atmosphere, no matter how sensitive the instrument or how high the altitude. Whatever may be the case, there is even less likelihood that animal life exists on Mars except perhaps of the most lowly kind, and if there is no oxygen at all, it is difficult to see how' the particular quality of animal life could have originated. Much, therefore, that we would like to know concerning life on Mars, if any, must wait until some highly sophisticated instruments have been landed actually on the planet’s surface, and probably only when a manned landing has been made.
One of the proposed devices for detecting the presence of living organisms on Mars by landed instruments, although only one of many under consideration or production, is a contraption designed to shoot out two weights with sticky strings, on arrival at the surface. The strings would then be wound back into a chamber containing a special broth in which it is hoped that any captured micro - organisms might multiply. A detection system would analyze gases thereby produced and would radio the results back to earth. But, as a Russian delegate to an international committee discussing the matter asked, does not the proposed experiment assume that Martian bacteria would have the same taste in broth as terrestrial ones? Experiments are now being devised, therefore, that would reveal the existence of exotic forms of life with which we are totally unfamiliar. This, if nothing more, is a most challenging mental exercise.
The finding and analysis of the simplest forms of life imaginable would supply information of inestimable value. We would know the answers to all kinds of questions that are applicable here to microbes and man alike. How is solar energy in-
tercepted and converted into living chemical energy? What, for instance, is the genetic mechanism for transmitting inheritance from generation tol generation? Is there sex? Is the energy. transfer system based on phosphorus,: as it is here? What evolutionary mechanisms operate? How are organisms adapted to the thin atmosphere, the low oxygen, and the Martian temperature range? And, after we have landed on Mars and begun to dig around, what evidence is there of a fossilized Martian past? With answers in hand, our understanding and appreciation of the nature of earthly life will have taken a tremendous step forward, and in a way that we cannoi otherwise accomplish.
As the director of the National Aeronautics And Space Administration Bioscience Program has said, “The search for life on Mars ultimately will require that Martian samples be studied in manned (preferably terrestrial) laboratories. Many of us believe that the retrieval of Martian samples’ should be recognized explicitly as the ultimate objective of exobiological misj. sions. It is doubtful if such retrieval can be accomplished satisfactorily by an unmanned expedition . . . Nos since Darwin, and Copernicus before him, has science had the opportunité for so great an impact on man’s unj derstanding of man. The scientific! question at stake in exobiology is, ill the opinion of many, the most excit ing, challenging and profound issue not only of the century, but of th; whole naturalistic movement that has characterized the history of westen thought for three hundred years. Whaf is at stake is the chance to gain I wholly new level of discussion on thtj meaning and nature of life.”
The stake is enormous and on n; account must be fumbled. If we arc careless and happen to establish or Mars various micro - organisms o| earthly origin before we know all w( need to know concerning what is trulyl Martian, our one chance will have gone for good. Sterilization of space craft and instruments is, therefore, ; major concern. It is also very difficult and has to be done step by step a? equipment is assembled. The greater difficulty will arise when manner vehicles are sent abroad, for thi healthiest human being is a hive of viruses, bacteria and protozoans, some of which are essential to health itselii Any such visit to Mars must therefore be made with extreme circumspection; for, as already demonstrated here or. earth, man appears to he a menace to all that attracts him. The longer if takes the blacksmiths of manned space travel to perfect their hardware, the better pleased the biologist will be.
Just before Mariner IV was launched last November, the National Academy of Sciences at Washington, D.C released the report of its space science board dealing with this overall program. The manned round trip to the moon still receives priority with regaré to time, and the experience may bí essential to assure tí later successful venture to Mars. But Mars is put a the top of the list as the primary goa after 1970. with exploration to be carried out initially by unmanned vehicler of the Saturn class, with suitable de contamination, and a hope held 01« for manned exploration by 1985. ★