A satellite designed to monitor the depletion of the ozone layer was launched Tuesday from an airplane off the California coast.
The Canadian Space Agency's Scientific Satellite is designed to last two years, orbiting Earth 15 times a day.
Attached to a rocket, the 330-pound satellite was dropped from the belly of a plane. After seconds of freefall, the rocket ignited and began carrying it into space. The satellite successfully separated from the rocket about 10 minutes later.
The satellite's two instruments were designed to improve understanding of the depletion of the ozone layer, with an emphasis on changes occurring over Canada and the Arctic. The instruments focus on the chemical processes that control the distribution of ozone in the atmosphere.
Depletion of the ozone layer is of concern since it offers protection from harmful ultraviolet rays. Increased exposure to UV radiation can cause skin cancer, eye damage and other health problems.
The launch comes at a time when there is evidence suggesting that the destruction of the ozone layer is slowing. Scientists say the slowdown mirrors a decline in the use of certain man-made chemicals.
Using NASA satellite observations, the scientists say the rate of the ozone layer depletion matches the drop in chlorofluorocarbons, used in refrigeration and air conditioning.
The 1987 Montreal Protocols, ratified by more than 170 countries, requires that CFCs be phased out of production and use in developing countries by 2010. Industrialized nations stopped using them in 1996.
Scientists said that it will take decades to repair the damage to the ozone layer, which helps protect the Earth from ultraviolet radiation from the sun.
"Ozone is still decreasing but just not as fast," said Mike Newchurch, associate professor at the University of Alabama and lead scientist on the study. "We are still decades away from total ozone recovery."