HERE in the rumpled foothills of the Santa Catalina Mountains, work is under way on an experiment unlike any other on earth. Bulldozers are clearing mesquite and cactus from a tract of Arizona desert to make room for a huge glass-and-steel structure that will eventually seal off eight people from the outside world for two years.
The project, Biosphere II, is intended to test the feasibility of creating a self-contained, closed environment, such as might be needed to sustain a manned base on the moon or Mars or on the ocean floor.
It will also act as a sophisticated laboratory to study Earth ecology, perhaps yielding clues on such phenomena as the ``greenhouse effect'' and the impact of creeping deserts in Africa. The project is the most ambitious experiment of its kind to date. Researchers involved believe it could ``revolutionize'' the life sciences. But skeptics consider it quixotic - and certainly not assured of success. ``Nothing has been done on this scale before,'' says Margaret Augustine, project director.
The unusual greenhouse-like structure is intended to be a microcosm of Earth, which project creators consider ``Biosphere I.'' It will contain seven ecological zones, including a tropical rain forest, marshland, desert, savanna, a 50-foot-high ``mountain,'' and an ``ocean'' deep enough to scuba dive in. There will be a small farm and a five-story living area complete with library, exercise room, and plumbing and electrical shops.
Once they enter the airtight shell in late 1989, the inhabitants will be cut off from the outside world except for sunlight and communication. They will leave only in case of medical emergency.
In this glass cocoon, nothing will go to waste. Oxygen given off by the plants, for instance, will be used to revitalize the air for human breathing, while the carbon dioxide that people emit will be used by the plants. Water that evaporates from the ``ocean'' will be blown over to the rain forest, cool, condense, and fall as ``rain'' on the trees and plants. Some of it will be recycled back into the ocean. Human wastes will provide fertilizer for crops and food for fish, which in turn will nourish human beings. The trick will be to keep the cycles in balance, a task as tough as tuning a 12-string guitar.
``It is not a forgone conclusion that when we close the doors on Biosphere II it is going to work,'' one project researcher says.
The seven-year experiment is an outgrowth of work on ecology-oriented projects done by the London-based Institute of Ecotechnics. Space Biospheres Ventures, a private, for-profit firm, is managing the project here. Most of the money for the experiment, some $30 million, is being put up by maverick Texas millionaire Edward P. Bass, who has also underwritten, among other things, a hotel-study center in Nepal and a floating Chinese junk used for ocean study.
Despite its offbeat roots, the Biosphere project is drawing on a prodigious pool of scientific talent. More than 200 scientists and researchers from such institutions as the Smithsonian's Marine Systems Laboratory, the New York Botanical Garden, and the University of Arizona's Environmental Research Laboratory are helping to design the ecosystems and choose the plants and animals that will populate the man-made world.
The project is also being closely watched by many in the ecology and space communities. A report last year by the National Commission on Space cited the project as the type of work on biospheres that must be done if man is ever to colonize the moon or Mars.
Biosphere II will not be the first attempt to create a self-contained environment. For years, softball-size glass balls have been available containing shrimp and algae that can survive for long periods in their isolation. In Siberia, Soviet researchers have been experimenting with a small, artificially lit chamber that recycles air, water, and other resources and is believed to have housed people for up to five months. The National Aeronautics and Space Administration is working on self-sustaining systems for use in space. But because any system NASA develops will have to be shoehorned into spacecraft, the agency is working on highly engineered chambers that use mechancial means to recycle some resources. It is not, so far, putting people in its closed environments.
``The Biosphere II people are interested in studying complex biological systems,'' says Dr. James Bredt, head of a NASA ecological life-support project. Their system ``is radical in its size and complexity,'' he adds. But ``in general, they are putting systems together with existing technologies.''
The Biosphere is being built on a sprawling ranch 35 miles north of Tucson, Ariz. - a stark but serenely beautiful desert landscape of prickly pear and cholla cactus, big skies and bronze sunsets. Little has been done yet on the structure, but the site bustles with activity. Several greenhouses, stucco office buildings, and a test chamber have been set up where researchers are designing systems and selecting plant and animal species.
Once completed, Biosphere II will consist of a series of modern-looking glass pyramids and barrel-vaulted structures, as well as a mosquelike building that will house the eight ``biospherians,'' as they are called here. The complex will sprawl over 2.5 acres and contain 5 million cubic feet, about 1/25th of the volume of the Louisiana Superdome.
Thirteen candidates are ``in training'' for the eight slots. They are working in facilities on the site, such as the tissue culture lab, where disease-resistant and other plants are being cloned.
Most candidates come from research backgrounds. They harbor a Peace Corps-like enthusiasm about the contributions the project could make and seem unconcerned about being cloistered under glass for two years.
``I could stand on my head for two years if I had to,'' says Stephen Storm, one of the candidates. Taking a break from tissue-culture work, he adds, ``I don't think there is anything going on anywhere that has the potential of demonstrating the influence of life on the atmosphere as Biosphere II could.''
But what about cabin fever? ``I go days and days now without walking across a two-acre space,'' he says.
Another candidate, Kathleen Dyhr, Space Biospheres' director of information services, says: ``This is an opportunity to be on the frontier of knowledge. I've lived out in the bush. That was more isolation than this.''
The biospherians won't be without comforts. There will be TVs, stereos, computers, VCRs, and perhaps even kayaking on the 35-foot deep ``ocean.'' The inhabitants are expected to tend crops and do other maintenance work about four hours a day and spend a similar amount of time on research and observation.
For food, the mini-Earth will be stocked with goats, chickens, 200 to 300 species of fish, and many kinds of food crops. The key will be to keep all the cycles synchronized. In this delicate world, an insect outbreak could cause an ecological disaster.
Two examples illustrate how detailed the research is in trying to bring this about. Scientists are considering putting termites in the building to help break down the savanna grasses. But they are studying dozens of species of termites to find ones that won't eat the sealants bonding the glass together - or to find sealants the termites don't like.
Being looked for, too, is a pair of hummingbirds to help pollinate the agricultural plants. Hundreds of varieties have been studied to try to find the ones with the right-shaped beaks to fit into the wide range of flowers.
``This kind of work has never really been done before,'' says Margaret Augustine, over a lunch of beef teriyaki and bibb lettuce. To monitor the system, an extensive computer network will be used. More than 5,000 sensors will be placed at various points around the Biosphere, checking things right down to the temperature of individual plant leaves.
``It's definitely more complicated than trying to figure out a Rubik's cube,'' says Norberto Alvarez, in charge of the computer and monitoring systems for the project. Indeed, it is the complexity of the project that makes some outsiders skeptical of its feasibility.
``I think they are taking an awfully big leap forward,'' says William Oswald, a professor at the University of California, Berkeley, who has done extensive work on closed ecological systems for the United States Air Force. ``When you start incorporating people into a large system, it gets to be very complex.''
Among spinoffs researchers see from the project are better systems for purifying air and water, natural ways to control crop pests, disease-resistant plants, and innovative ways to heat and cool buildings.
Eventually, project managers envision Biospheres perhaps being marketed as safe places to test genetically engineered organisms, grow endangered plants, or measure the effects of increased carbon dioxide levels (the ``greenhouse effect'') on various ecosystems. Most important, however, is the knowledge scientists hope to gain by using Biosphere II as a looking glass for studying the Earth and man's impact on it.
``We are on the edge of an incredible voyage of discovery,'' asserts project director Augustine. ``I think it is going to create a revolution in the life sciences.''