Mars: The Riddle of the Red Planet

Mars was a distant shore and the men spread upon it in waves ... The first wave carried with it men accustomed to spaces and coldness and being alone ... They came and made things a little less empty, so that others would find courage to follow.

--Ray Bradbury, The Martian Chronicles

For centuries, in fiction as well as in fact, men have dreamed about going to Mars and exploring the Red Planet. Last week, on July 20, at 8:12 a.m. (E.D.T.)--seven years to the day after the first men walked on the moon--this dream became a reality. "Touchdown! We have touchdown!" shouted Project Manager James S. Martin Jr. as he watched the consoles at Pasadena's Jet Propulsion Laboratory. Only 17 sec. behind schedule, the lander was safely down on Mars' Chryse Planitia (golden plains).

"This has got to be the happiest time of my life," said Martin as he popped the cork on a bottle of champagne. "It's incredible to me that it all worked so perfectly." Scientists who had sweated through Viking's earlier delays and other technical problems greeted the landing with applause or jokes. A few were damp-eyed. Most, however, were simply overwhelmed by the implications of their accomplishment. "How many times does Columbus arrive in history?" asked Gerald Soffen, Viking project scientist. "We've just witnessed one of the arrivals. We are a privileged generation." For the first time, through an obedient and ingeniously contrived robot, man was about to gaze at a Martian landscape, to begin sifting through Martian soil for evidence that life exists beyond the earth.

Painted Desert. Like an apprehensive human who had plummeted from the sky onto alien soil, Viking first looked down at its footing, transmitting back to Pasadena the historic, if not dramatic first picture from the Martian surface. It showed one of the lander's round footpads resting upon an area of hard-packed soil strewn with pebbles and small rocks of varying sizes. At J.P.L., 212 million miles away, scientists could clearly see the rows of rivets on the lander's foot, late (Martian) afternoon shadows and--extending from rocks--dirt tails that might have been formed by the strong winds that frequently scour the planet's surface.

It was when Viking lifted its gaze and surveyed the landscape that man could really imagine standing on Chryse Planitia. "Terrific!" exclaimed the Viking scientists. "Fantastic!" There before them in a spectacular 300DEG panoramic view was a rock-strewn--and apparently lifeless--plain reminiscent of the deserts of Arizona and northern Mexico. Clearly visible were bright patches of sand and dunes, some low ridges, what seemed to be an eroded crater and a landscape littered with rocks. Some of the more distinctively shaped rocks were promptly given names like "Midas muffler" and "Dutch shoe" by scientists. On the horizon, about two miles away, was a ridge that could be the rim of a large impact crater from which many of the rocks may have been ejected. Scientists estimated that some of the boulders were as big as 12 ft. in diameter, large enough to have overturned the Viking lander had it put down in their midst.

Above the horizon, the Martian sky looked surprisingly bright*--evidence, say some scientists, that the atmosphere is richer than expected in light-diffusing particles. In the sky was a shadow-- perhaps a cloud composed of water vapor.

The illusion of standing on the Martian plain became even more vivid when scientists produced a color picture that confirmed the appropriateness of Mars' longtime sobriquet of Red Planet. The soil seemed to consist of a fine-grained reddish material interspersed with small blue-black or blue-green patches. Many of the rocks were also coated with a reddish stain, strongly suggesting the presence of iron that had rusted in the presence of atmospheric or waterbound oxygen. Other rocks, blue-green and opalescent, reminded some scientists of copper ore. After correcting the color values on the photograph, scientists decided that the sky, which looked blue in the original print, was really of a pinkish hue. All in all, the view, far from being alien and forbidding, seemed almost inviting. "Oh, gosh, that's just lovely," said Thomas Mutch, head of the team charged with interpreting Viking's photography. "You just wish you could be standing there, walking across that terrain."

The rhapsodic mood in the mission-control room at J.P.L. was in sharp contrast to the tense atmosphere earlier that morning when the Viking 1 lander responded to a command by separating from the orbiter and beginning its 3-hr. 17-min. descent to the surface. Penetrating the Martian atmosphere, it shed its clamshell-like protective covering, deployed a 53-ft.-diameter parachute to slow its descent, and shortly before touchdown fired its retrorockets to brake its fall further. Engineers at J.P.L. watched nervously as the signals on their consoles marked the completion of each stage of the landing procedure. Because the signals, traveling at the speed of light, took nearly 19 min. to travel from Viking back to earth, scientists at J.P.L. were only too well aware that while they waited, the lander had already met disaster-- or made history-- on Mars.

No Monsters. Once the first lander was safely down on Martian soil--thereby assuring at least partial success of the $1 billion, eight-year-long Viking project--scientists decided that they could afford to be less cautious with Viking 2, which is approaching Mars and scheduled to go into orbit on Aug. 7. Last week scientists were considering setting the second lander down in a rugged northern region that would be more hazardous for landing than Viking 1's site but potentially more interesting to geologists and biologists.

In the early flush of excitement about the landing and the first photographs, none of the Viking scientists seemed particularly disappointed that the pictures showed no obvious signs of life--no lichen, bushes or trees, nothing even remotely resembling an animal or the monsters or little green men beloved by generations of science-fiction writers. Said Exobiologist Carl Sagan: "The pictures do not suggest that the planet is filled, pole to pole, with living things." But, noted Sagan, nothing in the pictures ruled out the existence of life on the planet either. Soffen added that the lander's immediate vicinity held half a dozen niches in which conventional biology, including hundreds of life forms, could be detected in a desert on earth. "The microbes of Mars are within our grasp, if they are there," said Soffen. "There could be cockroaches under those rocks."

Indeed, Mars seems to possess many of the elements essential to life on earth. Most of Mars' visible water appears in the form of atmospheric vapor or ice locked in the planet's two polar caps (the surface pressure on Mars is so low* that liquid water would probably boil away). But liquid water apparently once did flow freely on the Martian surface in earlier days; Viking's orbital pictures show that the planet is crisscrossed by dry "riverbeds" and sinuous valleys, including a deep Grand Canyon-like depression called the Valles Marineris, that were probably carved out by running water. During Viking's descent, the lander's instruments sniffed and measured both nitrogen (3%) and argon (1.5%) in the Martian atmosphere. Nitrogen is an essential element in the molecules of terrestrial life. Also, the presence of approximately the same percentage of argon found in the earth's air suggests that Mars at one time had a denser atmosphere more conducive to the evolution of life. Said Dr. Michael McElroy, a Harvard University physicist: "At an early stage. Mars apparently had enough pressure to hold quantities of water." And even today, notes the scientist, Mars may be capable of supporting life. "Look at what we need for life," said McElroy. "We need water; that we have. We need nitrogen; that we have. Phosphorus, phosphates ... I see no reason to exclude, from every thing we know, the possibility of the evolution of life Ion Mars]."

Between now and mid-November, when Mars passes behind the sun and communications with earth are cut off, Viking's two cameras will take regular photographs of Chryse Planitia, observing what takes place throughout each Sol, or Martian day, of 24 hr. 37 min. Other instruments, meanwhile, will sample the contents of the Martian atmosphere, register the planet's temperatures, which range from a low of -200DEG during darkness to a high of +50DEG during the day, and record wind velocities, barometric pressures and humidity. A seismograph, placed aboard the Viking to detect Marsquakes and volcanic activity, was apparently not working at week's end, but scientists still had hopes that they could coax it into operation.

Balky Device. If scientists can fix another balky device--the lander's 10-ft.-long telescoping arm, which last week jammed in a partially extended position--Viking's most dramatic experiments should begin this week; the lander will start its search for life in the soil of Mars. Shortly after sunrise, eight days after the landing, an electric motor will whine in the thin air, and the slender arm, tipped with a shovel no bigger than a child's beach toy, will slide slowly out of the lander. Scooping up some 6 cu. cm. of soil (about a heaping tablespoonful), the arm will then lift, retract and twist, dumping the contents of its shovel into a round, sievelike opening in the lander's top. From there, the soil will go into a rotating carrousel, or distributor, that will feed carefully measured samples into what must certainly rate as one of the age's technological masterpieces--the Viking Lander Biology Instrument.

Built by TRW of Redondo Beach, Calif., at a cost of about $50 million and housing some 40,000 components--pumps, chambers, filters and electronic parts--the biology instrument is the equivalent of a university biology laboratory in capability--but not in size. The entire package--including much of the equipment to transmit its findings back to earth--is crammed into a box occupying only 1 cu. ft., about the dimensions of the average automobile battery.

The biology lab will be looking for the signs of the kind of life that scientists believe is most likely to exist on Mars: microorganisms that live in the planet's red soil. In three separate experiments, each of which can be run four times for confirmation and control purposes, the Viking biology lab will test for evidence of:

GROWTH. On earth, plants depend on photosynthesis, the process by which they remove carbon dioxide from the air and, using sunlight as their energy source, convert the carbon to organic matter. Viking's first life-seeking experiment--called pyrolytic release--will attempt to determine whether Mars has organisms that can do the same. The biology instrument will take a 1/4-cu.-cm. soil sample and incubate it for up to five days under simulated Martian sunlight in a chamber filled with carbon dioxide and carbon monoxide containing radioactive carbon 14. Any organisms present in the sample should assimilate carbon--and thus radioactive carbon 14 from the atmosphere in the chamber.

At the end of the incubation period, the chamber atmosphere will be flushed (into a special container in order to avoid contaminating the Martian atmosphere) to remove any carbon 14 that has not been ingested by the organisms. Then the soil sample will be heated to a temperature of 625DEG C. (1057DEG F.) to break down the organisms' cells and vaporize the organic material. The cooking will release whatever carbon 14 has been assimilated during the incubation period, providing Viking's sensitive detectors with at least initial evidence that organisms are growing on Mars.

METABOLISM. Terrestrial life breaks down and uses nutrients and releases waste products and gases, a process called metabolism. Viking will attempt to determine whether any Martian organisms do the same thing, by means of a study called the labeled-release experiment. A sample of Martian soil will be loaded into a test chamber, then moistened with a substance scientists have named "chicken soup," a nutrient broth rich in vitamins and amino acids and containing radioactive carbon 14. The sample will then be incubated at a temperature of 47DEG F. for up to eleven days. During the experiment, any organism that functions by metabolism is likely to consume the nutrient and release gases that contain radioactively labeled wastes. Viking's sensors are capable of detecting them.

RESPIRATION. Living organisms on earth alter their environment as they live, breathe, eat and reproduce. To determine whether Martian organisms do likewise, Viking will conduct a third experiment, called gas exchange. It will submerge a soil sample in a liquid nutrient, then incubate the dirt for up to twelve days in an atmosphere of helium, krypton and carbon dioxide. The lab will then sample the atmosphere in the chamber at regular intervals, searching for the gases generally produced during the processes of life--molecular hydrogen, nitrogen, oxygen, methane and carbon dioxide.

Should Viking find any indications of growth, metabolism or respiration in the soil of Mars, the excitement--and the implications of the discovery--will be unprecedented. The existence of even the most rudimentary Martian organism would prove that the evolution of life on earth was not an isolated occurrence. Indeed, it would strongly suggest what many scientists already believe: life is commonplace in the universe. In the Milky Way galaxy alone, for example, there are probably hundreds of millions of sunlike stars, many with planets capable of harboring life. If life exists on both earth and Mars, the odds are good that it has evolved on other planets too.

Even if the Viking landers fail to detect living organisms, the possibility of life on Mars will not be precluded. With the Viking biological package, says Carl Sagan, "we simply may be asking the wrong questions." In other words, the experiments can tell only if there is earthlike life in the particular soil samples. Martian life could be based on a chemistry completely different from that on earth. Then, too, Viking, which landed on a site selected more for safety than scientific value, could simply be looking in the wrong part of the planet. The lander does not move and thus cannot tell what may lie even over the nearest hill.

Whatever the additional findings of Viking 1, and of Viking 2 afterward, the billion-dollar project has already paid off handsomely--and, in a way, has even provided what it set out to find. For, as Science-Fiction Writer Bradbury says, "From this point on, there is life on Mars--an extension of our sensibilities. Man is reaching across space and touching Mars. Our life is on Mars now."

*In contrast to the lunar sky, which, because the moon has no atmosphere, looks black.

*Equivalent to terrestrial air pressure at an altitude of 100,000ft.

This file is automatically generated by a robot program, so viewer discretion is required.