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1 .This is Scientific American 60-Second Space. I'm Clara Moskowitz. Got a minute?
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2 .Searches for extraterrestrial intelligence have focused on various signs of life.
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3 .And one signature of alien intelligence may be, cough, cough, air pollution.
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4 .NASA's James Webb Space Telescope, due to launch in 2018, should be powerful enough to detect chlorofluorocarbons, CFCs.
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5 .These ozone-destroying chemicals are used in aerosol sprays on Earth.
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6 .Maybe another planet's denizens also employ them.
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7 .A new analysis of this idea notes that aliens would have to be heavy users.
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8 .The Webb scope could only detect the chemicals if they were 10 times more prevalent than here on Earth.
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9 .And even then, the planet would have to orbit a special kind of star, a white dwarf, for the CFCs to show up.
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10 .White dwarfs, the ultimate destiny of stars like the sun¡ªmaximize the pollution signal.
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11 .The study is in the Astrophysical Journal.
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12 .CFCs could hang around in a planet's atmosphere for a long time.
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13 .So if an extraterrestrial civilization wised up and stopped polluting, we might still see the effects.
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14 .Even a society that managed to destroy itself long ago could leave a chemical trace.
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15 .Let's hope that's not how they discover us.
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16 .Thanks for the minute, for Scientific American 60-Second Space. I'm Clara Moskowitz.
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