Detecting intelligent life that's light years away: Greenhouse gases could signal alien activity

Detecting the presence of intelligent life on planets outside our solar system may be possible by identifying certain artificial greenhouse gases. A recent study conducted by UC Riverside explores the possibility of detecting terraformed planets through the detection of specific gases in their atmospheres. While these gases may have negative implications on Earth due to their contribution to global warming, they could serve as indicators of a technology-using civilization on exoplanets. This was reported by SSPDaily.

These gases, known as technosignatures, are not naturally occurring in significant amounts and would need to be manufactured. The researchers have proposed five gases including fluorinated versions of methane, ethane, and propane, along with nitrogen and fluorine or sulfur and fluorine combinations. These gases are extensively used in industrial applications on Earth, such as manufacturing computer chips.

One significant advantage of these gases for terraforming purposes is their potent greenhouse effect. For instance, sulfur hexafluoride has 23,500 times the warming potential of carbon dioxide. Even a small quantity could raise the temperature of a frozen planet enough to support liquid water on its surface.

Additionally, these gases have an advantage in terms of longevity. They can persist in an Earth-like atmosphere for up to 50,000 years, requiring less frequent replenishment to maintain a hospitable climate.

Unlike other proposed technosignature gases like CFCs, which harm the ozone layer, the fluorinated gases discussed in the study are chemically inert, making them a more viable option. CFCs are short-lived and can be easily broken apart, making their detection more challenging.

An important aspect in identifying these gases is their ability to absorb infrared radiation, which results in an infrared signature that can potentially be detected using space-based telescopes. Scientists believe that with existing or planned technology, they could identify these gases in nearby exoplanetary systems.

The researchers performed simulations using the TRAPPIST-1 system as a model, located about 40 light-years away from Earth. This system with its seven known rocky planets is one of the most extensively studied planetary systems beyond our own, making it a feasible target for future observations.

They also considered the European LIFE mission as a means to detect these fluorinated gases. The mission aims to directly image planets using infrared light, widening the scope for investigating exoplanets compared to the James Webb Space Telescope, which relies on planetary transits.

Collaborating with the Swiss Federal Institute of Technology/PlanetS, NASA's Goddard Space Flight Center, the Blue Marble Space Institute of Science, and Paris University, the researchers are confident that upcoming missions to characterize planetary atmospheres could provide the means to detect technosignatures like these gases.

While the likelihood of discovering these gases in the near future cannot be quantified, the researchers are optimistic about the possibility. The advancement of technology has brought us closer than ever to the potential realization of finding signs of intelligent life. The ability to systematically search for life and intelligence in our galactic neighborhood marks an extraordinary achievement for our generation and suggests a promising path for future scientific exploration.