Life on Mars? NASA Has Been Testing Martian Soil for Decades to No Avail, but Keeps Trying

The planet Mars showing showing Terra Meridiani is seen in an undated NASA image. NASA will be sampling soil from the Martian surface. Reuters Pictures

Newsweek published this story under the headline "A Viking Goes to Mars" on August 18, 1975. In light of recent events involving NASA, Newsweek is republishing the story.

In the 1890s, American astronomer Percival Lowell astonished the world with his assertion that the planet Mars was inhabited by intelligent beings who had constructed a vast system of canals in a desperate effort to irrigate their dry, dying world. No serious scientists believe in intelligent Martians or the canals today, but many experts think, on the basis of evidence from a variety of spacecraft that have orbited or flown past the red planet, that its environment just might be hospitable enough to support some rudimentary forms of life. This week, a miniature biological laboratory will lift off from Cape Canaveral on an ambitious $1 billion venture that will directly test that possibility by sampling soil from the Martian surface. The unmanned spacecraft, named Viking, is due to go into orbit around Mars on June 18 of next year for two weeks' observation of the planet's desertlike surface and wispy atmosphere. Then on July 4, if all goes well, a small, bug-shaped capsule will descend to an area named Chryse, at the end of a 3,000 mile long canyon, about 20 degrees north of the Martian equator. Its descent will be slowed first by a parachute and then by retro-rockets aimed at an angle to prevent damage to the landing site.

Ten days later, a 10 foot mechanical arm will reach out of the craft to scoop up soil samples, which it will deposit in three separate containers. Automatically, special equipment on board the spacecraft will conduct experiments designed to detect any signs of life. One will monitor carbon dioxide, which would be produced if any microbes in the soil grow in a special nutrient solution; another will measure the presence, if any, of radioactive carbon; a third will seek evidence of photosynthesis—the absorption of sunlight by living things. "These three experiments will detect virtually any form of microbial life," says space-agency scientist Gerald A. Soffen, "although there may be exceptions."

What are the chances that either Viking A or its backup mission, Viking B, which is due to lift off next week, will find life on Mars? Quite low, according to the experts, although better than they seemed 10 years ago. At that time, the fly-by of Mariner 4 had revealed Mars as a crater-pocked, moonlike planet. But recent observations by both U.S. and Soviet spacecraft have suggested that Mars once possessed appreciable amounts of water—perhaps enough to support living things. Even if neither Viking detects life, the project's scientists will be consoled by the trove of other data the spacecraft are likely to acquire on the seismology, structure, meteorology and magnetism of the planet. And the possibility of life on Mars would still not finally be ruled out, because the planet could of course harbor living things in other locations, or in forms that are totally unlike those we know on Earth.