Australasian Science: Australia's authority on science since 1938

The Search for Alien Polluters

By David Reneke

Astronomers search for alien air pollution, and Earth-based lasers could zap space junk.

The full text of this article can be purchased from Informit.

We are on the threshold of “sniffing out” signs of alien life on other worlds. By studying exoplanet atmospheres, we can look for gases like oxygen and methane that only coexist if replenished by life. While these gases come from simple life forms like microbes, would advanced civilisations leave any detectable signs?

They might if they spew industrial pollution into the atmosphere. According to the Harvard Smithsonian Centre for Astrophysics, we could spot the fingerprints of certain pollutants under ideal conditions.“Human beings consider industrial pollution as a sign of intelligent life, but perhaps civilisations more advanced than us... will consider pollution as a sign of unintelligent life since it’s not smart to contaminate your own air,” says lead researcher Henry Lin.

The forthcoming James Webb Space Telescope should be able to detect chlorofluorocarbons (CFCs) at atmospheric levels ten times those on Earth – but only on an Earth-like planet circling a white dwarf star, which is what remains when a star like our Sun dies. The same scenario on an Earth-like planet orbiting a Sun-like star would require an instrument beyond JWST’s capabilities. However, a white dwarf still holds promise because recent observations are finding planets in similar environments.

While searching for CFCs could ferret out an existing alien civilisation, it could...

The full text of this article can be purchased from Informit.