Projections of Earth's Technosphere: Strategies for Observing Technosignatures on Terrestrial Exoplanets

Abstract

The search for technosignatures--remotely detectable evidence of extraterrestrial technology--draws upon examples from the recent history of Earth as well as projections of Earth's technosphere. Facilities like the Habitable Worlds Observatory (HWO) will significantly advance the feasibility of characterizing the atmospheres of habitable exoplanets at visible and near-infrared wavelengths, while other future mission concepts could extend this search to mid-infrared wavelengths. We draw upon a recently developed set of 10 self-consistent scenarios for future Earth technospheres as analogs for extraterrestrial technospheres, which we use to outline a stepwise technosignature search strategy, beginning with HWO and followed by other missions. We find that HWO could reveal elevated abundances of a CO${}_2$ + NO${}_2$ pair on planets with combustion and other large-scale industry, which could be observable in up to eight of the 10 scenarios. Follow-up radio observations could reveal narrowband directed transmissions, as occur in two of the scenarios. Further study involving direct detections at mid-infrared wavelengths with the Large Interferometer for Exoplanets could reveal spectral features from industry, such as the combinations of CO${}_2$ + CFC-11/12 in four scenarios and CO${}_2$ + CFC-11/12 + CF${}_4$ in one scenario; two of these also include the N${}_2$O + CH${}_4$ + NH${}_3$ triple from large-scale agriculture. Other mission concepts, such as a solar-gravitational-lens mission, could reveal large-scale surface features in two scenarios that would otherwise show no detectable technosignatures, while an interplanetary flyby or probe mission would be the most conclusive way to reveal the presence of technology on terrestrial exoplanets.

arXiv commentPublished open access in ApJ Letters

References in corpus (47)

• Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life
• Planetary Spectrum Generator: an accurate online radiative transfer suite for atmospheres, comets, small bodies and exoplanets
• Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment
• The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth
• The Habitability of Planets Orbiting M-dwarf Stars
• Exoplanet Biosignatures: A Framework for Their Assessment
• Large Interferometer For Exoplanets (LIFE): I. Improved exoplanet detection yield estimates for a large mid-infrared space-interferometer mission
• Disequilibrium biosignatures over Earth history and implications for detecting exoplanet life
• Habitability and Biosignatures of Hycean Worlds
• The Breakthrough Starshot System Model
• On detecting biospheres from chemical thermodynamic disequilibrium in planetary atmospheres
• Organic Haze as a Biosignature in Anoxic Earth-like Atmospheres
• Habitability and Spectroscopic Observability of Warm M-dwarf Exoplanets Evaluated with a 3D Chemistry-Climate Model
• SETI Observations of Exoplanets with the Allen Telescope Array
• Large Interferometer For Exoplanets (LIFE): II. Signal simulation, signal extraction and fundamental exoplanet parameters from single epoch observations
• The Case for Technosignatures: Why They May Be Abundant, Long-lived, Highly Detectable, and Unambiguous
• Combined analysis of the 12.8 and 15 $\mu m$ JWST/MIRI eclipse observations of TRAPPIST-1 b
• Nitrogen Dioxide Pollution as a Signature of Extraterrestrial Technology
• Dyson Spheres
• Detection Technique for Artificially-Illuminated Objects in the Outer Solar System and Beyond
• Natural and Artificial Spectral Edges in Exoplanets
• A roadmap for the atmospheric characterization of terrestrial exoplanets with JWST
• Kardashev's Classification at 50+: A Fine Vehicle with Room for Improvement
• Concepts for future missions to search for technosignatures
• Detectability of Chlorofluorocarbons in the Atmospheres of Habitable M-dwarf Planets
• Observational Signatures of Self-Destructive Civilisations
• On the bio-habitability of M-dwarf planets
• Resolved imaging of exoplanets with the solar gravitational lens
• Large Interferometer For Exoplanets (LIFE). X. Detectability of currently known exoplanets and synergies with future IR/O/UV reflected-starlight imaging missions
• The Breakthrough Listen Search for Intelligent Life: Technosignature Search of Transiting TESS Targets of Interest
• Finding Signs of Life on Earth-like Planets: High-resolution Transmission Spectra of Earth through time around FGKM stars
• Disruption of a Planetary Nitrogen Cycle as Evidence of Extraterrestrial Agriculture
• On a Morphology of Contact Scenario Space
• A Radio Technosignature Search of TRAPPIST-1 with the Allen Telescope Array
• Fully fluorinated non-carbon compounds NF3 and SF6 as ideal technosignature gases
• Earth Detecting Earth: At what distance could Earth's constellation of technosignatures be detected with present-day technology?
• Projections of Earth's technosphere: Scenario modeling, worldbuilding, and overview of remotely detectable technosignatures
• Interstellar communication. XI. Short pulse duration limits of optical SETI
• Imaging rotating and orbiting exoplanets with the solar gravitational lens
• Detecting Extraterrestrial Civilizations That Employ an Earth-level Deep Space Network
• Polycyclic Aromatic Hydrocarbons (PAHs) as an Extraterrestrial Atmospheric Technosignature
• Galactic settlement of low-mass stars as a resolution to the Fermi paradox
• Projections of Earth's Technosphere: Luminosity and Mass as Limits to Growth
• What if we find nothing? Bayesian analysis of the statistical information of null results in future exoplanet habitability and biosignature surveys
• Artificial Greenhouse Gases as Exoplanet Technosignatures
• Technosignatures longevity and Lindy's law
• The challenge of detecting remote spectroscopic signatures from radionuclides