(ORDO NEWS) — The James Webb Space Telescope (JWST), launched last December, has been slowly turning on its instruments and deploying its sun shield, and is now in the process of aligning its mirrors in preparation for work.
In a few months, the most powerful space telescope ever built will be looking at the stars. Astronomers hope that what JWST sees will change our understanding of the universe, as the Hubble Space Telescope did decades earlier.
One of the alluring features of JWST that Hubble has failed to realize is the ability to directly image planets orbiting distant stars and maybe, just maybe, detect signs of life.
The possibility of remote detection of biosignatures has been a hot topic in recent years. In our solar system, the recent discovery of phosphine in the atmosphere of Venus has prompted speculation that this chemical could be created by microbial life.
Similarly, remote sensing experts have suggested that plant life using photosynthesis for energy can be detected in infrared, as chlorophyll absorbs visible light but shows up brightly in infrared, giving leafy planets a distinct “red edge”. “.
A single-pixel photograph of a distant planet may contain enough information to tell us whether there is biological life there, based on the information stored in the wavelengths of light that enter the lens of a telescope.
But what about intelligent life? Can JWST detect civilizations similar to ours? How are we going to look for them? The best answers come from understanding what humanity’s presence on Earth looks like from space.
We emit waste heat (from industry, houses, etc.) and artificial light at night, but perhaps most importantly, we produce chemicals that fill our atmosphere with compounds that would otherwise not exist.
These artificial constituents of the atmosphere may be what give us away to distant aliens scanning the galaxy with their powerful telescope.
A recent paper, available as a preprint on arXiv, explores the possibility of using JWST to search for industrial pollutants in exoplanet atmospheres. The article focuses on chlorofluorocarbons (CFCs), which are produced commercially on Earth as refrigerants and cleaning agents.
CFCs are infamous for creating a huge hole in the Earth’s ozone layer in the 1980s, after which an international ban on their use in 1987 helped reduce CFC levels to less harmful levels.
These “powerful greenhouse agents with long atmospheric residence times”, if found elsewhere in the galaxy, are almost certainly the result of a civilization capable of rampant industrialization.
In other words, some of humanity’s worst by-products – our pollution – may be the very things that make us visible. And this means that we can find other species that can be just as dismissive of the atmosphere of their planet.
JWST’s freon search capabilities have some limitations. If the planet’s star is too bright, it will drown out the signal. Therefore, the telescope will be most successful when observing M stars, which are dim, long-lived red dwarfs.
The closest example is TRAPPIST-1, a red dwarf 40 light-years away with several Earth-sized planets orbiting in its habitable zone. JWST will be able to see CFCs on the TRAPPIST-1 planets because a dim star will not drown out the CFC signature the way a bright star like our Sun (a G-type star) would.
Conversely, a telescope like JWST on TRAPPIST-1 would not be able to see Earth’s freons: our Sun is simply too bright.
Unfortunately, M-class stars are usually not conducive to life, because when they are young they are unstable and send out powerful solar flares that can simply wipe out nascent life on nearby planets. However, they calm down with age, so this is not impossible. It just means that we have to moderate our expectations a bit.
Whatever we find or don’t find there, the fact that we will soon have the opportunity to look at it all is a game-changer.”
As the article concludes, “With the launch of JWST, humanity could be very close to a major milestone in SETI [search for extraterrestrial intelligence]: when we can detect from nearby stars not only powerful, deliberate, fleeting and highly directed transmissions like our own (for example, message of Arecibo), but consistent, passive technosignatures as powerful as our own.”
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