Potential Technosignature From Anomalously Low Deuterium/Hydrogen (D/H) 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 persists over geologic timescales, oceanic deuterium would diminish. For an ocean mass and initial D/H that are Earth-like, fusion power use of only ∼10 times that projected for humankind next century would deplete the deuterium-hydrogen ratio (D/H) in ∼(a few)×108 years to values below that of the local Interstellar Medium (ISM). Ocean masses of a few percent Earth’s would reach anomalously low D/H in ∼106 to 107 years. 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 from radio signals, anomalous D/H would persist for eons, even if civilizations perish or relocate.
We discuss wavelengths of strong absorption features for detecting D/H anomalies in atmospheric water vapor. These are vibrational O-D stretching at 3.7 μm in transmission spectroscopy of Earth-like worlds, ∼1.5 μm (in the wings of the 1.4 μm water band) in the shorter near-infrared for direct imaging by Habitable Worlds Observatory, and 3.7 μm or ∼7.5 μm (in the wings of the broad 6.3 μm bending vibration of water) for concepts like the Large Interferometer for Exoplanets (LIFE).
David C. Catling, Joshua Krissansen-Totton, Tyler D. Robinson
Comments: Submitted to Astrophys. J. on March 12, 2024. Accepted for publication on November 27, 2024
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2411.18595 [astro-ph.EP] (or arXiv:2411.18595v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2411.18595
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Submission history
From: David Catling
[v1] Wed, 27 Nov 2024 18:40:46 UTC (1,853 KB)
https://arxiv.org/abs/2411.18595
Astrobiology, Astrochemistry,
