Aura will study the good and the bad about ozone
The above sequence illustrates the growth of the Antarctic ozone hole. The ozone layer
protects the Earth from harmful UV radiation. (Image provided by NASA)
NASA’s Aura satellite has a big job ahead of it. Thanks to Rich Cebula ’78 and the dozens of
other scientists and technicians who have worked on the project, Aura is now poised
to begin its mission, continuously monitoring ozone levels in Earth’s lower and upper
atmosphere, tracking the gases active in ozone chemistry, and improving our ability
to predict ozone change.
Stratospheric ozone has decreased by 3 percent globally between 1980 and 2000, and
has thinned by 50 percent over Antarctica. Because the ozone layer blocks harmful
ultraviolet (UV) radiation from the Earth’s surface, this decline, if it continues,
is not good news for life on the planet. Too much UV-radiation exposure can cause
people to develop skin cancers and eye problems, harms other animals, and also affects
photosynthesis in plants, a factor that can adversely affect the entire land and marine
Although the ozone layer is naturally thicker in some places and thinner in others,
in the 1980s, scientists noticed the ozone layer was unusually thin over Antarctica
during its winter months. This became known as the “ozone hole.” Since it was first
observed, this “hole” has appeared in Antarctica every year during the late winter
Severe thinning of the ozone layer has actually been observed over both poles — the
Arctic and the Antarctic — and in other places over the globe, especially Northern
Europe. Scientists discovered that atmospheric ozone was being destroyed by chlorofluorocarbons
(CFCs), which are man-made chemicals used in aerosol sprays and refrigerants. Since
1987, many countries have stopped or reduced production of these chemicals. However,
those chemicals will linger in the atmosphere for decades before the ozone layer will
Since fewer chlorofluorocarbons are now being released into the atmosphere, is the
ozone layer getting back to normal? Scientists hope the Aura mission will help them
answer that question. Recent measurements by earlier satellite instruments seem to
suggest that the ozone layer may be decreasing at a slower rate than in the past.
However, getting rid of CFCs may not be enough to help the ozone recover. Climate
change — caused at least in part by the presence of the man-made greenhouse gases
carbon dioxide, methane, and nitrous oxide — could also slow down that recuperation.
Part of Aura’s mission is to provide better information about air quality and pollution,
greenhouse gases, and climate change.
Aura’s Ozone Monitoring Instrument (OMI), whose data Cebula will help analyze, is also
measuring “bad” ozone located in the Earth’s troposphere, extending about 10 miles
from sea level to just below the stratosphere. When ozone exists in the troposphere,
it acts as an air pollutant. Gasoline and diesel engines give off gases that create
ozone and smog, especially during the hot summer months. In humans, exposure to ozone
may cause lung damage. Small children and people with asthma are especially at risk.
Aura will help scientists follow the sources of this ozone and its precursors.
“So the information we hope to obtain during Aura’s mission is not just of consequence to scientists,” comments Cebula. “If you breathe
the air, you have a stake in this.”
> To return to the profile on Rich Cebula, click here.
> WEB EXTRA: To read about Rich Cebula's memories of working with analog computers
at IWU in the 1970s, click here.
> To read the official NASA web site about the Aura project, click here.