UC Riverside’s latest study identifies artificial greenhouse gases as potential indicators of alien terraforming, detectable with existing space technology. Discover how we might find signs of intelligent extraterrestrial life.
In a groundbreaking discovery, researchers at the University of California, Riverside, have identified artificial greenhouse gases as potential indicators of alien terraforming activities on distant exoplanets. This study, recently published in the Astrophysical Journal, suggests that these gases could be detected using current technology, such as the James Webb Space Telescope or a future European-led space telescope concept.
Terraforming, the process of modifying a planet to make it habitable, could involve the introduction of specific greenhouse gases to warm the planet. According to UCR astrobiologist and lead study author Edward Schwieterman, these gases, which do not naturally occur in significant quantities, would serve as technosignatures — signs of intelligent, technology-using life forms.
“For us, these gases are bad because we don’t want to increase warming. But they’d be good for a civilization that perhaps wanted to forestall an impending ice age or terraform an otherwise-uninhabitable planet in their system, as humans have proposed for Mars,” Schwieterman said in a news release.
The study identifies five gases commonly utilized in industrial applications on Earth, including the production of computer chips. These gases encompass fluorinated variants of methane, ethane and propane, as well as compounds formed from nitrogen and fluorine or sulfur and fluorine. Notably, sulfur hexafluoride possesses 23,500 times the warming potential of carbon dioxide, making it exceptionally effective for terraforming. Even a small quantity of this gas could transform a freezing planet into one where liquid water could exist on the surface.
So looking for signs of these gases in the atmosphere of other planets may indicated intentional planetary terraforming by intelligent life forms.
Another advantage of these gases, from an alien perspective, is their longevity. They could persist in an Earth-like atmosphere for up to 50,000 years, meaning they wouldn’t need frequent replenishment to maintain a hospitable climate.
The study also contrasts these gases with refrigerant chemicals like CFCs, which have been proposed as technosignatures in the past. However, CFCs are less advantageous because they destroy the ozone layer and are short-lived. In contrast, the fully fluorinated gases discussed in the new paper are chemically inert and would not damage an ozone layer.
The researchers simulated a planet in the TRAPPIST-1 system, approximately 40 light-years away from Earth, to demonstrate the detectability of these gases. The TRAPPIST-1 system, which contains seven known rocky planets, is one of the most studied planetary systems aside from our own and is a realistic target for current space-based telescopes.
Collaborators on this study include researchers from the Swiss Federal Institute of Technology/PlanetS, NASA’s Goddard Space Flight Center, the Blue Marble Space Institute of Science and Paris University.
While the team cannot quantify the likelihood of detecting these gases soon, they are optimistic about the potential. Schwieterman emphasized that the detection of these technosignatures could occur during missions already planned to characterize planetary atmospheres.
“You wouldn’t need extra effort to look for these technosignatures, if your telescope is already characterizing the planet for other reasons,” Schwieterman said. “And it would be jaw-droppingly amazing to find them.”
This research marks a significant step forward in the search for extraterrestrial life, leveraging advancements in technology to explore the cosmos for signs of intelligent civilizations.
“Our thought experiment shows how powerful our next-generation telescopes will be,” Daniel Angerhausen, a collaborator from the Swiss Federal Institute of Technology/PlanetS, added. “We are the first generation in history that has the technology to systematically look for life and intelligence in our galactic neighborhood.”