A Novel Atmospheric Technosignature Grading System to Optimize Detection of Extraterrestrial Activity on G-type Exoplanets Using Next-Generation Space Telescopes.

The quest for identifying Extraterrestrial Intelligence (ETI) presents an unparalleled opportunity to expand our understanding of the universe and our place in it. A planetary science-based approach has been devised to detect technosignatures, which are indicative of industrial activity, and thereby intelligent life. The approach involves identifying chemical compounds that are known to be byproducts of industrial activity and detecting their presence in the atmospheres of exoplanets by analyzing transmission spectra obtained using next-generation space telescopes such as the James Webb Space Telescope (JWST) and the Large Ultraviolet Optical Infrared Surveyor (LUVOIR). The combined detection range of these telescopes spans from 0.1 to 28.6 microns, enabling the measurement of exoplanetary atmospheric compositions through transmission spectroscopy within this zone. Despite the significance of this approach, prior research has lacked a systematic methodology for selecting, evaluating, and searching for technosignature candidates using these telescopes. This study proposes a comprehensive methodology that evaluates potential technosignature candidates based on 8criteria, including 7 industrial chemistry attributes and spectroscopic detectability. The detectability criteria enables the identification of unique features within each compound’s transmission spectral signatures in G-type (Earth-like) planetary atmospheres. G-type planets theoretically hold the highest probability of harboring ETI, due to their similar stellar parameters to Earth, a planet with confirmed technosingatures and ETI. The application of these systematic criteria has resulted in the classification/grading of 55 technosignature candidates into four types, ranging from type-1 (greatest) to type-4 (lowest) based on their technosignature potential. This grading system facilitates the prioritization of promising candidates (type-1 + type-2) for detection on G-type exoplanets using next-generation space telescopes, thereby advancing the search for ETI. Through the methodology, 32 compounds were identified as promising out of a list of 55 candidate compounds, with 8 of them demonstrating the highest technosignature potential as type-1 candidates. These 8 candidates should be the primary focus of future searches for ETI using next-generation telescopes. This research defines clearly what we should be looking for in the pursuit of ETI, and enables these telescopes to hone in on the most promising candidates, expediting the search for ETI and optimizing telescope operational efficiency.