Earth Detecting Earth: At what distance could Earth's constellation of technosignatures be detected with present-day technology?

Abstract

The field of the Search for Extraterrestrial Intelligence (SETI) searches for ``technosignatures'' that could provide the first detection of life beyond Earth through the technology that an extraterrestrial intelligence (ETI) may have created. Any given SETI survey, if no technosignatures are detected, should set upper limits based on the kinds of technosignatures it should have been able to detect; the sensitivity of many SETI searches requires that their target sources (e.g., Dyson spheres or Kardashev II/III level radio transmitters) emit with power far exceeding the kinds of technology humans have developed. In this paper, we instead turn our gaze Earthward, minimizing the axis of extrapolation by only considering transmission and detection methods commensurate with an Earth-2024 level. We evaluate the maximum distance of detectability for various present-day Earth technosignatures -- radio transmissions, atmospheric technosignatures, optical and infrared signatures, and objects in space or on planetary surfaces -- using only present-day Earth instruments, providing one of the first fully cross-wavelength comparisons of the growing toolbox of SETI techniques. In this framework, we find that Earth's space-detectable signatures span 13 orders of magnitude in detectability, with intermittent, celestially-targeted radio transmission (i.e., planetary radar) beating out its nearest non-radio competitor by a factor of $10^3$ in detection distance. This work highlights the growing range of ways that exoplanet technosignatures may be expressed, the growing complexity and visibility of the human impact upon our planet, and the continued importance of the radio frequencies in SETI.

18 pages, 1 figure, 2 tables, published in AJ

References in corpus (10)

• Detecting industrial pollution in the atmospheres of earth-like exoplanets
• Accretion mode versus radio morphology in the LOFAR Deep Fields
• Nitrogen Dioxide Pollution as a Signature of Extraterrestrial Technology
• Demonstration of Communication using Neutrinos
• Choosing a Maximum Drift Rate in a SETI Search: Astrophysical Considerations
• Concepts for future missions to search for technosignatures
• Detectability of Chlorofluorocarbons in the Atmospheres of Habitable M-dwarf Planets
• The Breakthrough Listen Search for Intelligent Life: Technosignature Search of Transiting TESS Targets of Interest
• Simulation of the Earth's radio leakage from mobile towers as seen from selected nearby stellar systems
• Improved Analysis of Clarke Exobelt Detectability

Cited by in corpus (3)

• Detecting Extraterrestrial Civilizations That Employ an Earth-level Deep Space Network
• Breakthrough Listen: A Technosignature Search Around 27 Eclipsing Exoplanets Selected from the Transiting Exoplanet Survey Satellite Catalogue
• Projections of Earth's Technosphere: Strategies for Observing Technosignatures on Terrestrial Exoplanets