About 30 years ago, researchers announced that ozone concentrations high in the atmosphere over the South Pole had hit an all-time low. This critical layer of the atmosphere that shields us from the Sun’s harmful UV rays had a ‘hole’ in it. And that hole was rapidly expanding. This discovery led to the Montreal Protocol, an international treaty that regulates production of ozone-destroying chemicals like chlorofluorocarbons, or CFCs. As a result, the ozone layer is now on the mend.



To study this layer of the atmosphere further, NASA has launched an ozone sensor to help monitor the long-term change in the ozone layer. Called SAGE III, short for Stratospheric Aerosol and Gas Experiment III, it will be installed on the International Space Station in 2017. SAGE III represents the fourth of a series of instruments that have used similar techniques to measure atmospheric ozone and aerosols, going back to 1979, with more than 25 years of on-orbit heritage.

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