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Simulations of Technosignature Gases Using the Planetary Spectrum Generator (PSG)

Presentation #402.07 in the session Extrasolar Planet Atmospheres — iPoster Session.

Published onJun 29, 2022
Simulations of Technosignature Gases Using the Planetary Spectrum Generator (PSG)

On Earth, artificially produced gases (many potent greenhouse gases) are emitted as a result of industrial processing. Examples of these gases include hydrofluorocarbons, perfluorocarbons, chlorofluorocarbons, hydrochlorofluorocarbons, nitrogen trifluoride and sulfur hexafluoride. It is also suspected that extraterrestrial civilizations with technology levels similar to or more advanced may also utilize these gases as a result of industrial processing. Advanced extraterrestrial societies may also use uninhabited planets within their planetary system as servicing planets, where higher abundances of technosignature gases are produced as a result of industrial processes on a planetary-wide scale. Detection of these artificially produced gases would be best accomplished using future large aperture telescopes or large baseline intereferometers equipped with imaging spectrometers sensitive in the infrared region of the electromagnetic spectrum. Many industrial-produced gases that represent potential candidates for future spectral observations have their fundamental vibrational modes within the wavelength range of 7.5 to 14 microns. One of the best candidates for detection is sulfur hexafluoride (SF6) — a stable chemical — with a long atmospheric resident time of 3200 years based on the IPCC AR4 report (Forster et al. 2007). SF6 has a strong spectral signature near 10.55 microns in the mid-infrared, and has an atmospheric concentration of approximately 10 parts-per-trillion (ppt) as of 2020. In addition to using SF6 in their industrial processes, it is possible that advanced extraterrestrial civilizations might utilize sulfur hexafluoride for climate modification on other rocky planets within their planetary system due to its potent greenhouse warming potential of 23500 times that of CO2 (IPCC, 2013). Thus, it is proposed to use future space telescopes to search all rocky planets within or in near proximity to the host star’s habital zone. In preparation for these future observations, it is of interest to use spectral modeling/simulation tools to generate synthetic spectra for various telescope configurations, instrument parameters, and observing geometries. This poster paper will present some recent simulations using the NASA GSFC Planetary Spectrum Generator (PSG) for various technosignature gases.

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