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.