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Science: New Image for Mars

5 minute read
TIME

Man’s old dream about life on Mars seemed to fade for good in 1965 when the first closeup pictures of the red planet were radioed back to earth by the U.S. spacecraft Mariner 4. The photographs revealed a barren planet that looked as dead as the moon. Lately, this view of Mars has been radically revised. Contrary to the first photographic impression, U.S. scientists told an international space conference in Madrid last week, Mars is still undergoing sharp climatic changes. Violent geological activity has left scars all across its crust and, most significant, there may be enough water on its surface to support the evolution of primitive life.

Russian Failure. These dramatic findings have come from the extraordinarily productive Mariner 9 spacecraft. Still alive and transmitting, the 1,200-lb. robot has sent back more than 6,800 pictures since it began circling the planet last November. By patiently matching and assembling these photographs, scientists at Caltech’s Jet Propulsion Laboratory have put together a jigsaw-puzzle-like map of a strip of Mars extending 30° above and below the equator as well as an overall view of its south polar cap. Indeed, detailed photographs, showing features as small as 100 yards across, were among the highlights of the 15th annual session of the international Committee on Space Research, attended by more than 1,000 scientists from 35 countries.

Russian delegates had less to crow about. A Soviet TV-equipped instrument package did reach Mars last December in company with Mariner 9. The Russian ship landed safely and even began sending signals. But the intense dust storm that was buffeting the planet at the time completely obscured the view. (“If you know, for example, what London fog is like, then you have an idea what was there,” explained Mikhail Marov, head of the Soviet Mars program.) After sending signals for only 20 seconds, the Russian vehicle apparently tumbled over in the high winds (perhaps as strong as 300 m.p.h.), leaving its antenna pointing in the wrong direction for any further transmissions.

High above, beyond that turbulent atmosphere, Mariner 9 had better luck. Once the storm subsided, it focused on a remarkable range of Martian features:

> An area of at least four towering volcanoes, some of which may still be showing signs of activity. They are dominated by gigantic Nix Olympica, with an upper rim estimated to be more than three times as tall as Mt. Everest, the earth’s highest peak.

> Highly jumbled chaotic terrain, including many canyons, some of which seem to have been carved out by flowing water in the recent geological past. The major feature of the region is a giant gorge that is reminiscent of the Great Rift Valley in East Africa. It is 2,500 miles long, 75 miles wide and nearly four miles deep.

> A heavily cratered region, presumably pounded by meteorites, that scientists are comparing to the lunar highlands. Earlier photographs of this pock-marked area led investigators to conclude—prematurely—that Mars was a planetary version of the moon.

Mariner’s most remarkable finding came in the south polar region. Astronomers had long been convinced that the southern polar cap consists largely of frozen carbon dioxide, and that it vanishes completely in the Martian summer only to reappear during the following winter’s freeze. Closeup pictures show that in fact Mars retains a small cap near the south pole that is 200 miles in diameter even at the height of summer. Judging from the configuration of the cap—for example, its sharp edges —some scientists deduce that it may be composed of frozen water.

Wobbling Axis. If water is indeed locked inside the Martian polar caps, its presence could have profound biological implications. Since the axis of the planet slowly wobbles, or precesses, as Mars travels around the sun, the polar regions are alternately exposed to increased doses of sunlight. As a result, every 25,000 years, ice in the polar regions may well melt, releasing moisture into the Martian atmosphere and causing rains that could turn the planet’s arid surface into a morass of fast-flowing rivers and streams, lakes and perhaps even short-lived seas. A more favored theory is that flash-flooding could occur when ice in the Martian soil is melted by volcanic heat. In either case, the flowing water could account for some of the canyons and perhaps even for what looks like a wave-eroded edge around Nix Olympica. Even more intriguing, the water might in the past have remained on the surface long enough in liquid form for rudimentary life to develop.

Another reading, made by Mariner’s ultraviolet spectrometer, also raised hopes that some life, however simple, could exist on Mars. The instrument confirmed the presence of atmospheric ozone, the three-atom form of oxygen that is also found in the upper layers of the earth’s atmosphere and acts as a crucial life-saving shield against the sun’s searing ultraviolet radiation. Presumably, the ozone could play the same protective role on Mars. Indeed, the U.S. Geological Survey’s Harold Masursky, a member of the Mariner team, was so excited by these discoveries that he talked openly last week of looking for fossils when men or their robot envoys finally begin to prowl the surface of the red planet.

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