Rendezvous with Mars

After a voyage of more than five months and 248 million miles, the first of a trio of terrestrial ships made its rendezvous with Mars late last week. Precisely on schedule, the 1,300-lb. U.S. Mariner 9 fired its retrorocket and went into a looping orbit around the red planet, swinging as close as 800 miles to the Martian surface. With that successful maneuver, controlled entirely by its onboard computer, the $76.8 million windmill-shaped robot became the first man-made satellite of another planet. As pictures of the dust-obscured Martian surface began reaching earth, delighted mission controllers at the Jet Propulsion Laboratory in Pasadena. Calif., reported that Mariner's twin TV cameras and ultraviolet and infra-red sensors were all performing flawlessly.

The Russians, for their part, continued to remain silent about their two unmanned craft, which are expected to reach Mars some five to ten days after Mariner. But U.S. scientists who recently visited Russia revealed last week that they had been told by their Soviet counterparts that Mars 2 and 3 will attempt to land instrumented packages on the Martian surface. That seemed to confirm speculation by U.S. space officials, who had anticipated a Russian landing attempt simply on the basis of the great lift-off weight of Mars 2 and 3 (about 10,000 lbs. each). If their landers work properly, the Russians will leapfrog ahead of the U.S. by at least four years in the exploration of Mars; NASA does not expect to launch its Viking landers before 1975.

Small Targets. For the time being, however, Mariner 9 was stealing the space show. Even before going into orbit, it took three series of pictures of Mars from distances varying between 535,000 and 70,000 miles, stored the images on tape, and then, on commands from mission control, transmitted them back home (the signals, traveling at the speed of light, took 6 1/2 minutes to reach earth). The early images were somewhat disappointing. Because much of Mars is shrouded by a raging dust storm that began last September, only a few features could be picked out. But the scientists were not top concerned. The storm is expected to die down within a few weeks, and if Mariner's systems continue working well, the spacecraft will take some 5,000 pictures over the next three months, mapping at least 70% of the Martian surface and providing an invaluable day-by-day record of its still unexplained changes of color.

Mariner's cameras have another assignment: photographing the tiny Martian moons, Phobos and Deimos. In fact, before last week's rendezvous they managed to catch 19 long shots of the outer moon, Deimos, and two of Phobos. In the course of the mission, scientists hope for much closer shots that will actually show surface features of these tiny bodies, which are so small (only a lew miles in diameter) that they appear as mere dots in earthbound telescopes. Closeup photographs of Phobos and Deimos (named after the sons of Mars, the Roman god of war) could finally put to rest the imaginative theory of Soviet Astrophysicist I.S. Shklovskii. In an attempt to explain certain peculiarities--now attributed to misinterpretation of data--in the orbit of Phobos. Shklovskii suggested in 1959 that the moonlet might be hollow, possibly a satellite lofted by some long-vanished civilization.

Like Mariner 9. Mars 2 and 3 each contain two TV cameras and sensors to sniff out the composition of the Martian atmosphere and surface. In addition, they are equipped with temperature gauges that can, by measuring natural microwaves from the planet, locate subsurface hot spots, including volcanoes. Their landers, believed to be a modified version of the Soviet Venera (Venus) capsules, will be released shortly before the mother ships go into orbit. They are probably equipped with parachutes and retrorockets to slow their descent through the thin Martian atmosphere. The landers are also thought to contain sensing gear designed to radio back data on the composition, temperature, density and pressure of the Martian atmosphere during the few minutes of descent; there is some doubt that the instrumentation can survive what U.S. scientists expect to be a relatively hard landing. In contrast, the U.S. Viking has been designed to settle gently to the surface and to transmit TV pictures and other signals from the Martian surface.

Life Precursors. Although Mariner and the Soviet Mars craft are equipped to measure water, oxygen, temperature and other factors important to the existence of life, prospects for biological activity in the harsh Martian environment are considered extremely dim. In fact, some scientists suggest that Mars may still be in an early stage of planetary evolution, during which such primordial processes as the venting of carbon dioxide and water from the interior are only beginning.

Not all scientists are yet willing to abandon the old dream of life on Mars. Caltech Biochemist Norman Horowitz, for instance, points to recent experiments showing that organic compounds--usually regarded as precursors of life--can be synthesized in a Mars-like environment. If Martian life does indeed exist, it will probably be safe from contamination by microbes carried by the Soviet landers; thermite bombs will be set off inside the capsules after the landings, in an effort to ensure the destruction of any tiny stowaways.

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