Science: 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 6½ 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.