The Moon-Faced Mars

When the full set of Martian pictures taken by the spaceship Mariner IV was released last week, Mariner's earth-bound master, Physicist William H. Pickering, had the White House itself as his gallery. President Johnson was on hand to present awards to Pickering and two other Mariner scientists.* For cautious experts, the best of the photographs neither proved nor precluded the possible existence of life on Mars, although the planet's rugged terrain seemed hardly hospitable enough for the hardiest of bacteria. The pictures were clearer and sharper than anyone had expected. At least one of them --No. 11 -- was described by Jet Propulsion Laboratory scientists as "one of the most remarkable scientific photographs of the age."

Much of the pictures' quality was in the eyes of the beholders -- the JPL men who had prepared long in advance to interpret every possible detail. The picture-interpretation team, led by Dr.

Robert Leighton, took aerial photos of a volcanic area in the Mojave Desert and degraded them to Mariner's 200-line resolution. They practiced on weather pictures taken by Tiros satellites and on rocket photos of the Earth. They pored over purposely fuzzed-up pictures of relief maps of Southern California. By matching their conclusions with the known features of the areas they studied, they learned how to judge distances and sizes, how to distinguish contours from shadows and reflections.

It was a painstaking preparation, but it paid off. From their analysis of the full set of Mariner pictures, the JPL scientists concluded:

-- Mars is more moonlike than Earthlike. The pictures showed 70 clearly distinguishable craters ranging in diameter from three miles to 75 miles; a few appeared to be rimmed with frost. If the Mariner sampling is representative, Mars may have at least 10,000 craters of the size shown in the pictures, compared with fewer than 200 meteor craters that can still be seen on Earth. -- The planet's pock-marked surface, judging by what is already known of the moon's face, must be ancient--perhaps 2 billion to 5 billion years old--and well preserved. Scientists infer that Mars has never had a significant amount of water or an atmosphere denser than it is now, or else the Martian surface would show more signs of erosion. -- There were no signs of the vaunted canals, and no Earthlike features such as mountain chains, great valleys or ocean basins.

Mars may not look much like Earth; the pictures are, in fact, testimony to the uniqueness of Earth in the solar system. But Mars could still hold some of the secrets of Earth's evolution. "If the Martian surface is truly in its primitive form," said Dr. Leighton, "that surface may prove to be the best--perhaps the only--place in the solar system still preserving clues to original organic development, traces of which have long since disappeared from Earth."

* Jack N. James of JPL and Oran Nicks of the National Aeronautics and Space Administration's lunar and planetary programs.

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