Exobiology: The Search for Martian Life

No one has yet found absolute proof that there is life on Mars. But impressive evidence has been mounting for years. Among the red areas that give the red planet its name, astronomers can see darker patches that change and fade through the Martian year in a manner that strongly suggests the seasonal growth of vegetation. When the thin icecaps at the planet’s poles disappear with the coming of the Martian spring, belts of darker color creep toward the equator, sometimes crossing it. This effect might be caused by some nonliving chemical change under the influence of drifting water vapor, but biological action is more likely.

It is so likely, in fact, that a group of eminent astronomers, physicists, biologists and chemists last week urged the National Aeronautics and Space Administration to underwrite an elaborate Martian research program that will find out for sure.

More from the Sun. Martian life, said the panel headed by Princeton Biologist Colin S. Pittendrigh and Stanford’s Nobel-prizewinning Geneticist Joshua Lederberg, must be hardy enough to survive long periods of extreme dryness and cold. Martian organisms may concentrate water vapor the way earthly plants collect small traces of carbon dioxide; they may even make their own water by chemical action. There is a possibility that they need no water at all, using some other liquid as a fluid medium.

Oxygen is known to be scarce on Mars, but many forms of earthly life live without free oxygen, and Martian life may do the same. The ultraviolet light from the sun that freely penetrates the thin Martian atmosphere would probably kill earthly plants and animals, but Martian life may have found some means to protect itself.

Laboratory Search. The search for this hardy life should not be carried out in a hasty, slam-bang manner, said the report. The first step, though, can be carried out at once: laboratory work aimed at determining just what kinds of life are chemically possible. If chemical systems are found that might be the basis of novel, non-earthly forms of life, the instruments sent to Mars should be equipped to look for them as well as for familiar life.

Telescopes at the bottom of the earth’s thick and turbulent atmosphere cannot learn many details about Mars, but the biggest of them, says the report, should give more attention to the Martian problem. Telescopes carried aloft by balloons should study Mars intensively through the transparent upper layers of the atmosphere, and satellite-carried telescopes should take the work another step forward.

Intimate Orbiter. Mariner IV, which will pass near Mars on July 14, may send back fascinating pictures of the planet’s large-scale topography. But later spacecraft will be far more useful after they kick themselves into orbits close to the red planet. They will be able to study Mars for long periods at close range, sending back several kinds of maplike pictures, including intimate views of Mars made by infra-red light and by radar. A single orbiter will be able to chronicle an entire cycle of the Martian seasons, watching the growth of vegetation (if it really is vegetation) and mapping the fleeting details that were once interpreted as the famous Martian “canals,” which are now thought to be optical illusions. It can measure the density of the planet’s atmosphere by dropping a small object and watching how it falls.

ABL. Final step, some time in the early 1970s, will be to land an ABL (Automated Biological Laboratory) equipped to search for and analyze anything resembling life, and to send reports back to earth by radio. The ABL must be prepared to select and analyze kinds of life unknown on earth. But there is little chance that any large hostile creatures will attack and destroy it. Martian life is probably lowly, but no one really knows.

Whether discovered by a flyby, an orbiter, or an ABL, the first proof of life on Mars will be a startling breakthrough in man’s quest for knowledge. It will be evidence that life is a normal phenomenon in the universe, not just an oddity limited to the earth. And if life has developed on both the earth and Mars, it almost certainly exists on millions or billions of planets; some of its forms must be more intelligent than anything that man can now imagine.