Science

Journey to the stars, part two: The Martian Chronicles

TERENCE DICKINSON August 1 1976
Science

Journey to the stars, part two: The Martian Chronicles

TERENCE DICKINSON August 1 1976

Journey to the stars, part two: The Martian Chronicles

Science

Seven years after the first Apollo landing (“. . . a giant leap for mankind”) and Star Trek (“. . . to boldly go where no man has gone before”) went into reruns, earthlings had become a trifle jaded about space. After all, Alan Shepard had already played golf on the moon and Captain Kirk had trekked through the galaxy, fighting Klingons and necking with spacebunnies. But then, along came Viking and with it, despite competition from the Olympics, some of the old excitement. Mars, the mysterious yet tantalizingly dose Red Planet of science fiction and scientific fascination, has been invaded—a neat switch on the old Orson Welles theme—by mechanical man. The spindly Martian lander Viking 1, remarkably similar to the Apollo module that set Neil Armstrong on the moon, touched down perfectly on the red, rockstrewn surface and ushered in a new era of exploration, a cosmic leap forward in man’s eternal quest for information and his search for other children of the universe. By any measure, it was a stunning achievement—and, inevitably, it was only the beginning. Generations to come will travel farther.

The most elaborate and, at one billion dollars, the most expensive unmanned space venture to date. Viking had strong overtones of a philosophical adventure—a quest for life beyond earth. Of the solar system’s eight other planets, only Mars seems remotely likely to harbor life as we know it. Mars is barely half earth’s diameter and 40% farther from the sun—a combination that has prevented it from retaining an atmosphere that apparently used to be as dense as our own. Occasionally the thin Martian atmosphere gets whipped into a savage maelstrom with gales sweeping reddish dust into storms that last for months. During the last reconnaissance of Mars, in 1971, Mariner 9 was frustrated by such a storm. But all was calm when Viking arrived after an 11-month, half-billionmile voyage. After two proposed landing sites were rejected because of rough terrain, U.S. scientists chose a location known as Chryse Planitia, on the basis of its low altitude (where there was more likely to be water) and smooth appearance.

Viking is mankind’s eyes, nose, hands and, to some extent, mind embodied in a robot on another world. But its nerve centre is the Jet Propulsion Laboratory (JPL) in Pasadena, California—a massive research facility run for the National Aeronautics and Space Administration by the California Institute of Technology— where some of the nearly 800 scientists and

technicians now working on the mission have spent eight years planning it. When safe landing was achieved at 8.12 a.m. EDT July 20, roars of approval surged through JPL. Even more dramatic were the photographs—the first from the surface of Mars. Barely two hours after the landing, JPL computers had converted the spacecraft’s electronic whisper into a desert scene strewn with rocks and pebbles. Then the camera turned its gaze toward the horizon. The picture was so sharp and revealed a scene of such incredible alien beauty that

some scientists quietly wept. The next day, a stunning color photo arrived.

Viking’s origins date back to 1906 when Percival Lowell’s Mars A nd Its Canals was published. Ever since, Western civilization has been obsessed by the thought that Mars may be inhabited. Although the Italian astronomer Giovanni Schiaparelli was the first to observe the dry river beds on Mars it was Lowell, the American, who embellished that concept—he translated the Italian word for “channels” (canali) into “canals”—to embody the idea of arti-

ficially constructed waterways created by a dying civilization. The Lowellian vision of Mars has never completely died, and it still haunts astronomers. When Viking’s first photos came in, Cornell University’s Carl Sagan, this generation’s most eloquent planetary scientist, found it necessary to say: “We don’t see any plants or trees or animals, at least not where Viking landed but we can’t conclude from this that there is no life on Mars.” Almost no one expected plants or animals—but many scientists do think microorganisms could be present in the soil. Says Sagan: “Many terrestrial microorganisms could survive indefinitely under Martian conditions.”

The question of life on Mars critically hinges on the abundance of water. Telescopes have detected discouragingly small amounts of water in the Martian atmosphere. What keeps the hopes of life searchers alive are hundreds of dried-up river beds on the planet. Since there is no water in the channels now they must have been carved some time in the planet’s past. The critical question is how long was the water present and where did it go? One of the first of Viking’s findings has shed some light on it. During the spacecraft’s entry

into the predominantly carbon dioxide Martian atmosphere it measured two previously unrecorded gases in significant amounts: argon and nitrogen. Nitrogen implies a different Mars must have existed billions of years ago. “This new information on the Martian atmosphere allows us for the first time to speculate on the early history of Mars,” says Dr. Michael McElroy, a Harvard University specialist on planetary atmospheres. To get this quantity of nitrogen (about 3% of the total) McElroy calculates that there once was the equivalent of 10 feet of water covering the entire planet. “There is no way that most of this could have escaped into space. It still has to be on the planet,” McElroy insists. “Some of it is in the polar caps along with the frozen carbon dioxide there but the rest of the water has to be underground in the form of permafrost.” At one time, scientists believe, Mars had an atmosphere similar to earth’s. But when? McElroy believes it happened during the first billion years of the solar system’s 4.6-billion-year existence. When asked if water flowed on Mars long enough to allow life to develop, Harold Masursky of the U.S. Geological Survey, a chief Viking experimenter, re-

plied: “That’s what Viking should tell us. The finding of nitrogen makes me more optimistic—it was the last barrier. Without nitrogen life is highly unlikely.” The life detection experiments are now in progress. After a balky start, a 10-foot arm came to life and reached from the side of the squat craft to grasp a handful of Martian soil. The arm then swung around and deposited the soil in a hopper where it was distributed to three experiments designed to detect fundamental life forms.

Meanwhile Viking 2, an exact replica of its predecessor, is nearing Mars. Touchdown, planned for September 4, will be in a region considered more likely to have underground water. But whether or not the Vikings detect life there are certain to be follow-up missions. What the Vikings find will determine the scope and timing of future Martian exploration. Even during the euphoria of the Viking 1 success, however, no one was talking of manned missions to Mars. Apart from the estimated $150 billion price tag, the feeling is humans are not necessary—yet. Says Carl Sagan: “It makes a great deal more sense to send smart machines rather than smart humans.” TERENCE DICKINSON

TERENCE DICKINSON