Looking for the Bodies

Edgar Rice Burroughs peopled Mars with bosomy princesses and Tarzan-like adventurers. H.G. Wells populated the planet with huge, insectlike creatures. NASA scientists have yet to find either maidens or monsters on the Red Planet, but their epoch-making explorations increasingly suggest that there may be more on Mars than rocks. Though the Viking 1 lander has yet to discover the organic compounds that would enable scientists to say with any confidence that there is life out there, it has sent back evidence that processes usually associated with life on earth also take place on Mars. Says Harold Klein, leader of the Viking biology team: "Mars is telling us something. The question is whether Mars is talking with a forked tongue or giving us the straight dope."

This week scientists are involved in a new effort to find the answer to this question. Two weeks ago Viking 2 dropped silently out of space and bumped to a landing on Mars' Utopia Planitia (plains of Utopia), some 4,600 miles east-northeast and almost halfway around the planet from Viking 1 (see map). The landing gave scientists some anxious moments. Shortly after separation from its lander, the Viking 2 orbiter lost its "lock" on the star Vega and began to roll, breaking its contact with mission controllers at the Jet Propulsion Laboratory in Pasadena, Calif. But even as engineers worked feverishly to correct the problem with the orbiter, the lander was performing perfectly, coasting through the thin Martian atmosphere to a landing only 32 seconds behind schedule. "It's a very interesting thing," commented Viking Project Manager James Martin. "The lander doesn't seem to need us."

The first view of Viking 2's new home, transmitted back to earth the following day, was also a surprise. Scientists had expected from orbital observations that the landing site would be covered with Sahara-like dunes. But the first panoramic pictures showed an area strikingly similar to that occupied by Viking 1: a relatively flat plain, strewn with porous, spongy-looking rocks that seemed as if they might be volcanic in origin and cut by a shallow channel that could have been carved by running water.

Scientists lost no time in studying Viking 2's new surroundings. With signals that took 21 minutes to traverse the 228,670,000 miles from earth to Mars, they swiveled the lander's cameras around for a better look at the Utopia site and the planet's salmon-pink sky, triggered its seismometers so that it could listen for Marsquakes (similar devices on Viking 1 have failed to work) and switched on its weather station instruments.

Exotic Chemistry. But the devices that got the most attention were those in Viking 2's biology laboratory, the small (1 cu. ft.) package designed to detect life on Mars. This week the lander is to stretch out its robot arm, scoop up a sample of Martian soil and dump it into the minilab, which will repeat the three life-seeking experiments already performed by Viking 1. If the scoop works and all goes according to schedule, the results of these experiments could be in early next week.

They will be awaited eagerly, for the results of the tests already done by Viking 1 have been ambiguous--teasingly hinting at the existence of life, yet failing to find a key element that would help confirm it. In one life-detection experiment, a soil sample that had been dampened with "chicken soup"--a nutrient broth designed to satisfy any Martian microbes' tastes--released surprisingly large quantities of oxygen. In another test, a sample that was also moistened with a nutrient and incubated released large amounts of carbon dioxide and carbon monoxide. Subsequent reruns of these tests by Viking 1 proved puzzling, however. The production of the telltale gases slumped, and the scientists reluctantly concluded that the reactions they had observed might just as easily have been produced by some sort of exotic extraterrestrial chemistry as by Martian microorganisms.

But an experiment designed to detect photosynthesis--the process by which green plants on earth use sunlight, water and carbon dioxide to make organic matter--was more encouraging. The data from Viking 1 showed that the Martian soil sample had absorbed carbon from the atmosphere in amounts that could not easily be explained by chemistry alone. When the experiment was performed using a sterilized sample, a much lower level of activity was observed, suggesting that organisms might have been killed. On earth, says Biochemist Norman Horowitz of the California Institute of Technology, this would have been considered "a weak but definitely positive biological signal." Despite this discovery, scientists are still unwilling to say that there is life on Mars. Viking 1's sophisticated gas chromatograph-mass spectrometer has yet to detect any evidence of the carbon-based organic compounds that constitute a basic ingredient of life, a fact which argues against its existence. "There's every sign of life except death," said a frustrated Klein last week. "Where are the bodies?"

If Viking 2, which has set down in a damper and thus potentially more fertile region of Mars than Viking 1, can find those biological bodies, it would not be a great surprise; Mars, after all, does contain all the elements necessary for the evolution of life. But even if no life is discovered, few scientists are likely to be disappointed, for the Viking mission is providing them with an unprecedented opportunity to examine another world. It has also given them an impetus for intensifying their explorations of Mars. Even as Viking 2 touched down, scientists were considering the possibilities of sending another lander, one able to move around, as Viking 1 and 2 cannot, to Mars during the next decade.

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