Potential Technosignature from Anomalously Low Deuterium/Hydrogen in Planetary Water Depleted by Nuclear Fusion Technology
Deuterium–deuterium (DD) fusion is viewed as an ideal energy source for humanity in the far future, given a vast seawater supply of D. Here, we consider long-lived, extraterrestrial, technological societies that develop DD fusion. If such a society persisted over geologic timescales, oceanic deuteri...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad99a9 |
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| author | David C. Catling Joshua Krissansen-Totton Tyler D. Robinson |
| author_facet | David C. Catling Joshua Krissansen-Totton Tyler D. Robinson |
| author_sort | David C. Catling |
| collection | DOAJ |
| description | Deuterium–deuterium (DD) fusion is viewed as an ideal energy source for humanity in the far future, given a vast seawater supply of D. Here, we consider long-lived, extraterrestrial, technological societies that develop DD fusion. If such a society persisted over geologic timescales, oceanic deuterium would diminish. For an ocean mass and initial deuterium/hydrogen (D/H) ratio that were Earth-like, fusion power use of only ∼10 times that projected for humankind next century would deplete the D/H ratio in ∼(a few) ×10 ^8 yr to values below that of the local interstellar medium (ISM). Ocean masses of a few percent of Earth’s would reach an anomalously low D/H in ∼10 ^6 –10 ^7 yr. The timescale shortens with greater energy consumption, smaller oceans, or lower initial D/H. Here, we suggest that anomalous D/H in planetary water below local ISM values of ∼16 × 10 ^−6 (set by Big Bang nucleosynthesis plus deuterium loss onto dust or small admixtures of deuterium-poor stellar material) may be a technosignature. Unlike SETI using radio signals, anomalous D/H would persist for eons, even if civilizations perished or relocated. We discuss the wavelengths of strong absorption features for detecting D/H anomalies in atmospheric water vapor. These are vibrational O–D stretching at 3.7 μ m in transmission spectroscopy of Earth-like worlds, ∼1.5 μ m (in the wings of the 1.4 μ m water band) in the shorter near-infrared for direct imaging by the Habitable Worlds Observatory, and ∼7.5-8 μ m (in the wings of the broad 6.3 μ m bending vibration of water) for concepts like the Large Interferometer for Exoplanets. |
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| language | English |
| publishDate | 2025-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-ab97b3e7688a4b5b8ad20c8be98a70ae2025-01-22T10:19:05ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01979213710.3847/1538-4357/ad99a9Potential Technosignature from Anomalously Low Deuterium/Hydrogen in Planetary Water Depleted by Nuclear Fusion TechnologyDavid C. Catling0https://orcid.org/0000-0001-5646-120XJoshua Krissansen-Totton1Tyler D. Robinson2https://orcid.org/0000-0002-3196-414XDepartment of Earth & Space Sciences, University of Washington , Seattle, WA 98195, USA ; dcatling@uw.edu; Virtual Planetary Laboratory, University of Washington , Seattle, WA 98195, USADepartment of Earth & Space Sciences, University of Washington , Seattle, WA 98195, USA ; dcatling@uw.edu; Virtual Planetary Laboratory, University of Washington , Seattle, WA 98195, USAVirtual Planetary Laboratory, University of Washington , Seattle, WA 98195, USA; Lunar & Planetary Laboratory, University of Arizona , AZ 85721, USADeuterium–deuterium (DD) fusion is viewed as an ideal energy source for humanity in the far future, given a vast seawater supply of D. Here, we consider long-lived, extraterrestrial, technological societies that develop DD fusion. If such a society persisted over geologic timescales, oceanic deuterium would diminish. For an ocean mass and initial deuterium/hydrogen (D/H) ratio that were Earth-like, fusion power use of only ∼10 times that projected for humankind next century would deplete the D/H ratio in ∼(a few) ×10 ^8 yr to values below that of the local interstellar medium (ISM). Ocean masses of a few percent of Earth’s would reach an anomalously low D/H in ∼10 ^6 –10 ^7 yr. The timescale shortens with greater energy consumption, smaller oceans, or lower initial D/H. Here, we suggest that anomalous D/H in planetary water below local ISM values of ∼16 × 10 ^−6 (set by Big Bang nucleosynthesis plus deuterium loss onto dust or small admixtures of deuterium-poor stellar material) may be a technosignature. Unlike SETI using radio signals, anomalous D/H would persist for eons, even if civilizations perished or relocated. We discuss the wavelengths of strong absorption features for detecting D/H anomalies in atmospheric water vapor. These are vibrational O–D stretching at 3.7 μ m in transmission spectroscopy of Earth-like worlds, ∼1.5 μ m (in the wings of the 1.4 μ m water band) in the shorter near-infrared for direct imaging by the Habitable Worlds Observatory, and ∼7.5-8 μ m (in the wings of the broad 6.3 μ m bending vibration of water) for concepts like the Large Interferometer for Exoplanets.https://doi.org/10.3847/1538-4357/ad99a9TechnosignaturesNuclear fusionSearch for extraterrestrial intelligenceTransmission spectroscopyIsotope shiftsAstrobiology |
| spellingShingle | David C. Catling Joshua Krissansen-Totton Tyler D. Robinson Potential Technosignature from Anomalously Low Deuterium/Hydrogen in Planetary Water Depleted by Nuclear Fusion Technology The Astrophysical Journal Technosignatures Nuclear fusion Search for extraterrestrial intelligence Transmission spectroscopy Isotope shifts Astrobiology |
| title | Potential Technosignature from Anomalously Low Deuterium/Hydrogen in Planetary Water Depleted by Nuclear Fusion Technology |
| title_full | Potential Technosignature from Anomalously Low Deuterium/Hydrogen in Planetary Water Depleted by Nuclear Fusion Technology |
| title_fullStr | Potential Technosignature from Anomalously Low Deuterium/Hydrogen in Planetary Water Depleted by Nuclear Fusion Technology |
| title_full_unstemmed | Potential Technosignature from Anomalously Low Deuterium/Hydrogen in Planetary Water Depleted by Nuclear Fusion Technology |
| title_short | Potential Technosignature from Anomalously Low Deuterium/Hydrogen in Planetary Water Depleted by Nuclear Fusion Technology |
| title_sort | potential technosignature from anomalously low deuterium hydrogen in planetary water depleted by nuclear fusion technology |
| topic | Technosignatures Nuclear fusion Search for extraterrestrial intelligence Transmission spectroscopy Isotope shifts Astrobiology |
| url | https://doi.org/10.3847/1538-4357/ad99a9 |
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