Looking for Life

Although an onslaught of astronaut sniffles and sore throats at Cape Kennedy last week delayed the orbital flight of Apollo 9, an unmanned spacecraft named Mariner 6 was successfully launched from a nearby pad. Its ambitious mission: to search for evidence that life can exist on Mars.

High above the atmosphere, Mariner unfolded its four rectangular solar panels and wheeled around until sensors locked onto the sun and the star Canopus, stabilizing the 850-lb. craft in space. Then, right on course, the complex space traveler settled down for a five-month, 226 million-mile journey that is scheduled to take it to within 2,000 miles of Mars on July 31.

Enigmatic Features. As Mariner 6 approaches its goal this summer, one of its two television cameras will begin shooting a series of pictures that will show the full disk of the planet six times more clearly than it can be seen through Earth telescopes. While Mariner 6 sweeps over the equatorial regions of Mars, both cameras will shoot a series of 24 closeup pictures programmed to include areas of interest on the red planet: permanent and variable dark markings, "canals" and "oases," white markings on crater rims and other enigmatic features that have been seen through terrestrial telescopes or were photographed four years ago during Mariner 4's historic flight (TIME cover, July 23, 1965). The pictures will be converted into digital "on-off" signals and radioed back to earth, which, at the time, will be about 60 million miles away.

Five days later, if all goes well, Mariner 7, a second Mars probe, will make a sweep across the south polar regions of the planet, shooting closeup photographs of the white polar cap and areas that appear to change color seasonally. Mariner 7 is scheduled to be launched on March 24, but will take less time than its predecessor to make the trip; its trajectory is different and the Earth will have moved some 25 million miles closer to Mars during the month that separates the shots.

Between them, the two probes should photograph about 20% of the surface of Mars, compared to the 1% covered by Mariner 4. In addition, batteries of instruments aboard the spacecraft will measure surface temperatures and analyze the composition of the atmosphere and of the south polar ice cap.

Spring Vegetation? Sophisticated as they are, Mariners 6 and 7 will at best be able to determine only the possibility of life on Mars. Their cameras, which can pick out features twelve times smaller than Mariner 4 could see, will nonetheless be unable to distinguish objects less than 900 ft. across. Says Robert Leighton, a California Institute of Technology physicist who is in charge of Mariner's TV experiments: "At the worst, we should be able to kill a lot of old legends about the dark lines being canals carrying water from polar ice caps to oases in the desert--or the ones that say the vast regions that change color every spring are vegetation."

More definitive answers will have to await the four additional Mars probes now planned by NASA. In 1971, during the next close approach of Mars, the U.S. will send two photographic spacecraft into orbit around the planet for at least 90 days each. The orbiters will take a series of pictures showing seasonal changes on Mars, map the entire surface and enable scientists to choose likely looking spots for future landings. High priority will be given to sites with the warmest temperatures and greatest traces of moisture.

But the riddle of life on Mars will probably not be solved until at least 1973, when versatile "Project Viking" capsules ejected from still another pair of orbiting spacecraft are scheduled to make soft landings on the surface of the planet. In a search for any obvious evidence of life, TV cameras aboard the landers will take pictures of the immediate surroundings. Delicate instruments will sniff and analyze the atmosphere at ground level. Mechanical devices will gulp up, digest and chemically analyze Martian soil for clues to life. In their findings, relayed back to Earth by radio, man may find the exciting evidence that life exists elsewhere in the universe.

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