Don't Let This Happen to Your Planet
Ozone stinks. People who breathe it gag as their lungs burn. The EPA classifies ground-level ozone as air pollution.
Yet without it, life on Earth would be impossible.
A fragile layer of ozone 25 km above Earth's surface is all that stands between us and some of the harshest UV rays from the sun. The ozone molecule O3 blocks radiation which would otherwise burn skin and cause cancer. On Mars, which has no ozone layer to protect it, solar UV rays strafe the surface with deadly effect, leaving the apparently lifeless planet without the simplest of organic molecules in the upper millimeters of exposed Martian soil.
To keep track of our planet's ozone layer, NASA is about to launch the most sophisticated space-based ozone sensor ever: SAGE III, slated for installation on the International Space Station in 2014.
"The ISS is in the perfect orbit for SAGE III," says Joe Zawodny, Project Scientist for the instrument at the Langley Research Center. "It will be able to monitor ozone all around the Earth during all seasons of the year."
SAGE III works by using the Sun and Moon as light sources. When either one rises or sets behind the edge of the Earth, SAGE III analyzes the light that passes through Earth's atmosphere. Ozone and other molecules absorb specific wavelengths that reveal their density, temperature and location.
"SAGE III is, essentially, analyzing the colors of the sunset to track ozone," says Zawodny. "It sounds romantic, but this is hard science."
Researchers began to worry about ozone in the early 1970s when University of California chemists Frank “Sherry” Rowland and Mario Molina testified before Congress that manmade CFCs, a key ingredient of common aerosol sprays, could destroy ozone in the stratosphere. Their fears were soon realized. In 1985, researchers with the British Antarctic Survey announced abnormally low ozone concentrations above Halley Bay near the South Pole. Our planet had an "ozone hole," and it was rapidly growing.
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