In the near future, sports spectators may enjoy climate-controlled stadiums with an outdoor feeling. The linchpin in this development is a flexible, clear covering already on the drawing board.
The product may be on the market within two years, according to Paul Gossen, an engineer with Geiger Berger Associates, a New York firm pioneering in the construction of air-supported domes. Among the bubble-topped stadiums the firm has designed are Syracuse University's Carrier Dome and the Silverdome in Pontiac, Mich., plus Minneapolis's Metrodome, which is under construction.
These relatively inexpensive domes are much like inflatable tents that let in some natural light, but not enough to grow grass. The Silverdome, for example, is about 8 percent translucent. Grass requires translucency of at least 75 percent.
Besides being clear, the ideal dome fabric must be strong and fire resistant. The prototype is still under development, as are new species of grass that require lower light levels.
The prospect of covered natural turf fields appeals to many athletes and spectators tired of games in what Geiger Berger president David Geiger calls ''well-lit caves.'' Pro football players, in fact, have begun lobbying for grass fields in all NFL stadiums. The players are convinced real grass is safer. It is also aesthetically more pleasing and less likely to produce wild, kangaroo bounces.
Artificial turf was invented only after grass failed to grow in Houston's Astrodome during the mid-'60s. A green nylon carpet called AstroTurf was developed to solve the problem, which went even further. Sunlight streaming through the dome often blinded fielders as it bounced off the roof's numerous glass panels. Since these panels didn't serve their intended purpose anyhow, they were coated with an opaque sealer.
Domes have since taken on the character of overgrown, indoor arenas, rather than open-air stadiums. Little by little, however, engineering breakthroughs are letting the sunshine in.