Detection of Alien Terraforming Possible through Artificial Greenhouse Gases

Researchers at UC Riverside have identified specific artificial greenhouse gases that could indicate a planet has been terraformed by intelligent extraterrestrial life. Using advanced technology such as the James Webb Space Telescope or a future European-led space telescope, scientists could detect these gases even in low concentrations in the atmospheres of exoplanets.

The study, led by astrobiologist Edward Schwieterman, focuses on five gases—fluorinated versions of methane, ethane, and propane, along with gases made of nitrogen and fluorine or sulfur and fluorine—commonly used in Earth’s industrial applications. These gases are highly effective in warming a planet, with some like sulfur hexafluoride having up to 23,500 times the warming power of carbon dioxide.

Unlike naturally occurring gases, these compounds must be manufactured, making their presence a clear sign of technological activity, dubbed ‘technosignatures.’ The gases can persist in an atmosphere for up to 50,000 years, reducing the frequency of replenishment required to maintain a habitable climate.

The research includes a simulation of detecting these gases on a planet in the TRAPPIST-1 system, located about 40 light-years from Earth. This system, which features seven known rocky planets, is a prime candidate for examination by current or future space telescopes.

Collaborators on the study include experts from the Swiss Federal Institute of Technology, NASA’s Goddard Space Flight Center, the Blue Marble Space Institute of Science, and Paris University. The findings, detailed in the Astrophysical Journal, highlight the feasibility of identifying technosignatures with existing and upcoming missions aimed at characterizing planetary atmospheres.