Cambridge, Mass. — A helium-filled balloon, 50 times the size of the Goodyear blimp, hovers 35 miles above the earth. Slowly it unreels a cable, dangling a 300-pound pack of instruments 12 miles below.
Harvard inventor James Anderson, backed by the National Aeronautics and space Administration (NASA), hopes this Jules Verne-like contraption will find evidence about the allegedly ailing ozone layer, earth's shield from the destructive rays of the sun.
Its launch tentatively in set for September at New Mexico's White Sands Missile Range. But shifting wind patterns may delay the takeoff until next April.
The crux of the experiment is to establish better methods of directly observing the earth's ozone layer, which is made up of a molecular form with three oxygen atoms per molecule. It acts as protective layer that absorbs harmful solar ultra-violet (UV) radiation some 10 to 25 miles above the earth's surface. Some scientists are concerned that damage to this ozone layer could increase the amount of UV reaching the surface.
Some have suspected that synthetic chemicals called fluorocarbons (tagged CFCs by scientists) may deplete ozone, but proof is difficult to obtain. Generally too high for aircraft measurements and too low for satellite observation, the ozone has been sampled by balloon and parachutes drops of scientific recording equipment. Such initial experimentation has revealed significant amounts, some 16 percent, of ozone depletion due to CFCs. On the basis of such findings, the federal government in 1978 banned the use fluorocarbons in aerosal spray cans. More recent computations put the ozone depletion figure at about 8 percent.
NASA and the Environmental Protection Agency (EPA) need more concrete data if further controls are to be imposed.
Some claim more regulation of flourocarbons is needed because of the long-lasting effect of ozone destruction. CFCs are stable molecular structures that remain in the earth's atmosphere some 50 to 70 years before moving into the ozone layer itself. From there the destruction of the ozone molecules is relatively quick, within a few seconds. The process is thought to continue as part of an on-going chain reaction.
Drawbacks to more control of flourocarbon producers are numerous. At the moment there is no known replacement for flourocarbons, which are used in everything from foam insulation to the coolant in refrigerants and air conditioners. Currently there are insufficient scientific data to support completely the flourocarbon/ozone relationship, although a recent satellite observation reported possible evidence.
In response to the need for more direct observation of the ozone, NASA, which spends some $18 million annually in ozone research, has given Professor Anderson
The aim of the study, says Anderson, is to determine a cause-effect relationship between the man-made flourocarbons and the destruction of the ozone.
Anderson hopes that the scrolling ability of his equipment will provide a more comprehensive profile of the ozone layer. The instruments will roll up and down the line several times taking continous measurements at different altitudes. Ozone levels are known to vary a great deal depending upon solar activity, shifting air masses, and the earth's different latitudes.
The experiment has not been without its problems. For one thing, a 12-mile cable had to be found that would not only support itself and the instruments, but also would be able to withstand strong winds at high altitudes. A synthetic fiber, Kevlar, developed by DuPont, was the answer. Ten times stronger than steel and weighing only 200 pounds, the line cane support itself and the 300 -pound instrument pack it will carry.
Should the novel experiment work, the spool arrangement is likely to be used in other atmospheric observations. Says Lester Machta of the National Oceanic and Atmospheric Administration, and experiment is "exceedingly important."
But even with new "hard data," the regulation of flourocarbon pollution is far from certain.
The fluorocarbon industry is a multimillion-dollar a year business in the US and other countries. Unlike aerosal fluorocarbons, which were replaced relatively simply with a hydrocarbon substitute, the fluorocarbons used as a coolant (often under the Du Pont trademark of "freon") in refrigerators and air conditioners as well as in foam insulation, are unique. Despite millions of dollars and years of testing in both the private and public sectors, no known substitute for those fluorocarbons now exists.
The EPA and Congress are cautions about further regulation. The Ozone Depletion Validation Act, sponsored by Sen. Llyod Bentsen (D) of Texas, is currently an amendment to the Clean Air Act, which comes up for congressional reauthorization next year. The bill requires more direct observation of the ozone layer before imposing further regulations.It also stipulates the need for an international agreement regarding fluorocarbon pollution. Japan and several European Economic Community countries are also big fluorocarbon producers.