One "wasteful" clue may reveal aliens to NASA Webb telescope

Scientists may only need one single-pixel photo to to reveal "waste heat" from another planet.
Brad Bergan
A computer-generated image of the Earth's ozone (left), and NASA's Webb (right).1, 2

NASA's James Webb Space Telescope could do the unthinkable: It may reveal the presence of alien life, but not via a noble interstellar message, colossal megastructure, or some other testament to the supreme wisdom of the extraterrestrial variety.

Instead, the Webb might detect alien intelligence by picking up traces of air pollution from the excesses of an alien civilization — much like ours, according to a recent study that has yet to be peer-reviewed.

It wouldn't be the kind of first contact with aliens that we want. But it might be the kind we deserve.

Webb might detect alien life as a "red edge"

Launched last December, the Webb telescope has continued to power up and unfurl its suite of highly advanced instruments and sunshield, respectively. Now perfectly positioned in orbit of the second Lagrange (L2) point beyond the Earth's orbit of the sun, where thrusters are no longer needed, Webb is aligning its golden, honeycomb-like mirrors in preparation for the most awe-inspiring tour of the universe ever achieved.

And it's going to blow even the Hubble Space Telescope away.

One capability Hubble lacked that scientists expect from Webb is the first direct capture of images of alien worlds in orbit of distant stars. If all the conditions are right, Webb might even pick up signs of life. It's an exciting possibility, which is why detecting bio- and technosignatures on other worlds has remained a popular topic for years.

Here in our solar system, a recent discovery of phosphine lurking in Venus' atmosphere led some scientists to wonder whether a microbial lifeform might have created it. And this discovery led to a new proposal for detecting plant life. Since plants generate energy via photosynthesis — a process detectable in infrared wavelengths, as visible light is swallowed up by chlorophyll — an alien world lush with foliage might register in Webb's array as a clear "red edge," according to a report in Universe Today.

Aliens can detect our industrial excesses. But we can see theirs

Using data from the Webb telescope, scientists on Earth might only require a single-pixel image of a faraway alien world to glean enough information to strongly suggest the presence of biological life in the cosmos. Detecting more complex life — perhaps intelligent, like ours (or better) — could be more complicated. But the best way to guess how we'd find it is by examining how we show up on Earth, but from a point-of-view of space.

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"Waste heat"

Our civilization releases massive amounts of waste heat, from countless households, and the endless production of multiple industries. Add to this the signature glow of artificial night through the night, and from low-Earth orbit, our planet is bustling with activity. But from a distance, these signs of life become fainter, which means anyone looking for the presence of humans might have to scan for chemicals.

Crucially, the best way to detect a society like ours from deep space is by looking for the traces of the chemicals we produce and put out into the atmosphere — specifically, compounds that wouldn't be generated on a planet like ours without human industry.

It's ironic that the damage done to our biosphere by many of these compounds could be the way alien civilizations on distant worlds spot us with their telescope — but it also means we can do the same to them, provided we have a telescope with enough power.

NASA's Webb telescope could detect CFCs on distant alien worlds

And that's exactly what Webb can do. In the preprint study, a team of scientists explored how we might look for these synthetic chemical compounds — specifically, chlorofluorocarbons (CFCs) — which are generated by industries that use cleaning agents and refrigerants. This is a compound that infamously tore a colossal hole in our planet's ozone layer in the 1980s. It got so bad that their use was banned internationally in 1987, in a bid to lower CFCs to more manageable levels.

But looking for these "potent greenhouse agents with long atmospheric residence times" elsewhere in the Milky Way would almost certainly reveal the presence of a thriving alien civilization, perhaps struggling with the same excesses of industry that are threatening the viability of human life on Earth.

Depending on the distance between Webb and an alien world with CFCs or some other harmful chemical compound in its atmosphere, humans might be forced to speculate about the alien civilization's current status.

After all, there's no guarantee that our civilization will survive its current suite of social and ecological antagonisms. If we spot an alien world 1,000 light-years away, we could be looking at a world that has evolved beyond pollution-creating energy sources.

On the other hand, that alien planet may have failed to correct its excesses, or might even have already destroyed itself from nuclear annihilation. Since light has a finite speed, the only way we'd know for sure that an alien civilization is definitely there, as we see it, is if it's close enough to minimize the temporal lag in images due to the speed of light.

Let's cross our fingers that alien civilizations set mainly good precedents and that we can follow their example.