Technosignatures: Greenhouse gases could reveal extraterrestrial life
Artificial greenhouse gases in a planetary atmosphere last a long time and could be detected with today's technology. What researchers expect from this.
Illustration of various planetary technosignatures, including artificial atmospheric gases.
(Image: Sohail Wasif/UC Riverside)
Artificially produced greenhouse gases could lead researchers on the trail of extraterrestrial life in the future. Scientists at the University of California in Riverside have named five gases that could serve as so-called "technosignatures". They would be clear signs that a planet is inhabited or at least used by intelligent, technology-using life forms. They have announced their findings in a study published in the Astrophysical Journal.
The gases, including fluorinated versions of methane, ethane and propane, could be used by an advanced civilization to terraform a planet. But humanity has also used greenhouse gases to make its planet recognizable as an inhabited planet. The gases are characterized by their extreme effectiveness, long service life and good detectability. According to the study, they could be detected even in low concentrations using existing technology such as the James Webb Space Telescope. The researchers simulated their discovery on a planet in the TRAPPIST-1 system, around 40 light years away from Earth.
A problem for Earth, a blessing elsewhere
"For us, these gases are problematic because we would rather not increase global warming. But for a civilization that might want to prevent an impending ice age or terraform an otherwise uninhabitable planet, they could be useful", astrobiologist Edward Schwieterman explains. On Earth, the gases are produced in semiconductor manufacturing, for example. As they do not occur in large quantities in nature, at least by terrestrial standards, they would be obviously attributable to a civilization.
"The long lifespan of these gases makes them excellent technosignatures that can be systematically searched for, compared to short-lived signals", said study co-author Daniel Angerhausen from ETH Zurich. "These signatures could even outlive their civilization if their geoengineering experiments fail." Some gases could be detected in the atmosphere for up to 50,000 years. Researchers from NASA's Goddard Space Flight Center, the Blue Marble Space Institute of Science and the University of Paris were also involved in the study.
The scientists see the results of the thought experiment, combined with the performance of future space telescopes, as a major step forward in the search for extraterrestrial life: "We are the first generation in history to have the technology to systematically search for life and intelligence in our galactic neighborhood", said Angerhausen.
(mki)