SECTION: Special Space Policy Briefing

HEADLINE: Creating Life on Other Planets;
For Now, 'Terraforming' Is Still a Science Fiction Term, But a Handful of Visionary Thinkers Are Exploring the Possibilities of Developing Earth-Like Conditions Elsewhere in the Solar System to Create New Habitats. Mars Would Be First.

BYLINE: By James Oberg

At the beginning of human civilization, people built fires to warm caves and diverted rivers to irrigate dry lands. By accident, they let their herds graze regions treeless and released enough smoke to change rain patterns. For better and for worse, human activity is making its mark on Earth's environment.

Today, scientists and ordinary citizens consider the future in which human activities threaten many current features of the biosphere. They also are learning about the catastrophic history of Earth in which natural disasters have repeatedly ruined the biosphere, sometimes leading to mass extinctions of animals and plants. Mankind is not the only - or even the major - threat to Earth.

A handful of visionary thinkers scattered over the planet in space and time have suggested that deliberate human activity is necessary not just to repair man-made environmental damage on Earth, but also to forestall the inevitable natural disasters by artificial technical means.

Current global climate patterns are unusually hospitable and can be expected to worsen even without artificial damage, unless purposeful steps are taken to counteract these natural trends.

Furthermore, these visionaries suggest, other worlds in the solar system can be transformed to host earth-like biospheres, to become "new earths."

This may be either for the first time in their sterile histories, or as a "repair" to ecological catastrophes in their past which wiped out the beginnings of native life forms.

The traditional science fiction term for this concept is "terraforming." It was coined about 50 years ago and has been the theme of a long series of stories, novels, even movies. Its definition includes the artificial introduction and maintenance of "earth-like" conditions on other planets in the solar system and beyond to serve as new habitats for future humanity.

The far-future concept has gradually been moving from the purely imaginary stage to the "speculative" stage of thought. Scientists both in NASA and the university community have considered some of the practical aspects, and environmental conferences have addressed some ethical aspects.

In 1978 and again in 1987, two informal colloquia were held in Houston during the annual Lunar and Planetary Science Conferences. Special issues of the "Journal of the British Interplanetary Society" (London) have recently been devoted to the topic. The May 1991 issue of LIFE magazine features the concept as its cover story.

Mars is the most commonly mentioned subject of the first terraforming attempts. On a local scale, large, deep meteor craters could be formed by steering asteroids to impact the surface, forming warm oases with thick air and central lakes.

On a planetary scale, warming could be induced by darkening the surface (using the black dust from the nearby moonlet Deimos) or concentrating sunlight via large thin solar mirrors. Permafrost would melt, freeing water and carbon dioxide. Hardy pioneering green plants would convert the atmosphere into a breathable one.

Venus is also attractive because of its size, but the severe heat could only be lowered by locking away most of the atmosphere in mineral form. The Earth's moon could be given an atmosphere stable for thousands of years by impacting an icy asteroid (or a minor moonlet of Saturn) less than 100 miles across. Other worlds from Mercury to the moons of Jupiter each present unique challenges.

Such activity must depend on technologies now barely imaginable. But the time has come to think about the idea.

While unlikely to be a budgetary line item for a few centuries, the concept can underscore what must be known soon about Earth itself as science and technology face the challenge of coming centuries on our home world.

Merely submitting passively to natural cycles means enduring solar variability (which can shift desert belts north or south by hundreds of miles), volcanic outbursts (which can put a decade's worth of pollutants into the stratosphere within hours), infalling asteroids (which can wipe out counties, countries, even hemispheres), and other events which are real and relatively frequent. Such disasters might instead - with know-how and wisdom and will - be lightened or even entirely averted.

Armed with such experience and insights, future civilizations on Earth would be in a position to do more than tentatively visit other worlds. They could take part in the spread of life beyond its current limits, out into the galaxy.

If Mars is to be first of the "new earths," it is fitting that this age-old symbol of war, the blood-red beacon in our skies proclaiming death be transformed into a triumph of humankind's life-giving instincts over its all-too-frequently exercised death-dealing instincts.