Potential technosignature from anomalously low deuterium/hydrogen (D/H) in planetary water depleted by nuclear fusion technology

David C. Catling; Joshua Krissansen-Totton; Tyler D. Robinson

REVIEW 3 major objections 6 minor 16 references

Potential technosignature from anomalously low deuterium/hydrogen (D/H) in planetary water depleted by nuclear fusion technology

T0 review · 3 major / 6 minor · reviewed 2026-08-12 · deepseek-v4-flash

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Pith's one-line read The paper argues that a long-lived civilization running deuterium-deuterium fusion would deplete its oceans' deuterium-to-hydrogen ratio below the interstellar-medium background within hundreds of millions of years, and that the resulting…

desk verdict D/H depletion from fusion is a genuinely new, durable technosignature idea with clean arithmetic; the detectability numbers are optimistic and the initial-D/H premise needs a quantitative look. read the letter →

arxiv 2411.18595 v2 pith:3WWFFB6Q submitted 2024-11-27 astro-ph.EP

David C. Catling , Joshua Krissansen-Totton , Tyler D. Robinson This is my paper · ORCID

classification astro-ph.EP

keywords deuterium/hydrogenratiotechnosignaturedeuterium-deuteriumfusionexoplanetwaterinterstellarmediumHDOspectroscopyhabitablezoneexoplanetsSETI

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper argues that sustained deuterium-deuterium fusion power—the energy source most plausibly able to support an advanced civilization over geologic time—would slowly consume the deuterium in that civilization's own oceans. Starting from an Earth-like ocean D/H of $155.76\times 10^{-6}$, a civilization drawing 1000 terawatts (about ten times the projected peak human demand) would push the ratio below the local interstellar-medium value of about $16\times 10^{-6}$ in roughly $10^8$ years; smaller oceans of a few percent of Earth's mass would do it in $10^6$–$10^7$ years. Because the depleted ocean would remain anomalous long after the civilization died or left, the paper proposes that water with D/H below the local ISM is a technosignature: a fossil trace of past industry rather than a message from living beings. It then shows that the deficit would be visible at specific infrared wavelengths through the HDO isotopologue of water vapor, most strongly in the O-D stretching vibration near 3.7 $\mu$m.

What carries the argument

The carrying mechanism is a simple inventory identity: the time to reach anomalous D/H equals the deuterium mass above the threshold divided by the rate at which fusion consumes deuterium, which is set by power draw and the reaction's energy yield. That identity is anchored by the measured specific energy of DD fusion, $3.53\times 10^{11}$ J per gram of D, and by the SMOW initial ratio. On the observational side, the central object is the HDO molecule: its fundamental O-D stretch near 3.7 $\mu$m and weaker overtone and combination bands near 1.5 and 7.5 $\mu$m provide the spectral handles by which a remote observer could see that deuterium is missing relative to protium.

What would settle it

Measure the HDO/H$_2$O ratio near 3.7 $\mu$m in transmission spectra of a dozen or more temperate rocky exoplanets around small stars, or in reflected light near 1.5 $\mu$m with a future direct-imaging observatory. If the measured D/H distribution clusters near the local ISM value rather than near Earth-like enrichment, or if sub-ISM D/H appears on planets whose host stars and cometary material have normal ISM D/H with no other industrial markers, then a low D/H reading would no longer be a dependable fusion technosignature.

Watch

Extended reading notes

Core claim

The central claim is that DD fusion on a planetary scale depletes the deuterium-to-hydrogen ratio of an ocean and that the depleted ratio can be distinguished from every known natural astronomical source. The paper's calculation uses the net fusion reaction $3\mathrm{D}\to{}^4\mathrm{He}+p+n$, which releases $3.53\times 10^{11}$ J per gram of deuterium, and assumes 33% energy-conversion efficiency; with an Earth-mass ocean and 1000 TW of continuous power, the D/H would fall from the SMOW value to the local ISM threshold in roughly 170 million years. The same arithmetic scales linearly: a 4%-Earth ocean reaches the threshold in about 7 million years, and higher power or lower initial D/H shortens the wait. The detection side rests on the fact that removing deuterium from water vapor removes the HDO isotopologue's absorption features while leaving $\mathrm{H_2O}$ largely unchanged; the 3.7 $\mu$m O-D stretch is the cleanest sign, with weaker discriminators near 1.5 $\mu$m in reflected light and near 7.5 $\mu$m in thermal emission. The paper also notes that a D/H ratio merely below other rocky planets' values, even if still above the ISM, could be anomalous once comparative data exist.

Load-bearing premise

The scenario assumes that rocky exoplanets begin with water deuterium-enriched well above the interstellar-medium ratio, as Earth's ocean is; if many rocky planets instead acquire water with near-ISM or lower D/H, a sub-ISM reading would not be uniquely attributable to fusion technology.

Editorial extensions

If this is right

A D/H measurement below about $16 \times 10^{-6}$ in exoplanet water would, under the paper's assumptions, be a strong candidate technosignature.
Because the depletion persists after the civilization is gone, searches would not need to catch a civilization in action; a survey of many rocky planets accumulates sensitivity to past as well as present technology.
A null result would give quantitative constraints: a lack of sub-ISM D/H across many planets rules out the combination of high power use and long technological lifetimes.
The proposed 3.7 $\mu$m O-D stretch feature is the most promising near-term target, potentially within reach of existing transit-spectroscopy capabilities for nearby M-dwarf planets.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

Beyond the paper: because the depletion signal is cumulative, a population survey of D/H across rocky exoplanets would act as a fossil record of regional industrial history, not just a snapshot of active broadcasts; the authors gesture at this but do not develop the survey statistics.
A concrete follow-up the paper leaves open is modeling how Rayleigh distillation at cold poles and mantle degassing of undepleted water would dilute or mimic the fusion signal; computing disk-averaged versus pole-on viewing geometries would sharpen the claimed detectability.
If sub-ISM D/H is ever found, the most direct confirmation would be a correlated absence of HDO in the same atmosphere under different phase angles, combined with stellar and cometary D/H that are normal; that conjunction is hard to produce naturally.

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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Worth reading. The idea is new to me: a civilization that runs D-D fusion for geological timescales pulls its ocean's D/H below the local ISM value, and that makes a persistent technosignature that survives the civilization. The energy arithmetic is clean—specific energy per gram of D from CODATA masses, 33% efficiency, 1000 TW fiducial—and the ~170 Myr timescale for an Earth-like ocean follows from stated assumptions. The SMART radiative transfer work is a plus; they identify concrete wavelengths (3.7 µm, ~1.5 µm, ~7.5 µm) and give SNR estimates for JWST, HWO, and LIFE. That is more actionable than most SETI proposals.

The biggest soft spot is the detectability analysis. Figures 4–6 remove all HDO from the atmosphere, but the anomaly threshold is 90% depletion, not 100%. So the quoted integration times are optimistic; partial-depletion models would give more honest numbers. The paper calls itself proof-of-concept and lists this as future work, so it is a limitation, not a fatal flaw.

The second soft spot is the load-bearing assumption that rocky exoplanet water starts with Earth-like D/H. The pre-stellar-ice argument is plausible but unquantified, and the authors themselves note that lower initial D/H just shortens the fusion timescale. If a large fraction of rocky planets accrete near-ISM or protosolar D/H, then sub-ISM values could arise from Rayleigh distillation or atmospheric escape without any technology, breaking the uniqueness. The paper does discuss tropospheric D-depletion to ~85–90% of SMOW, which is still an order of magnitude above ISM, so for Earth-like starting ratios the concern is minor. But the distribution of initial D/H on rocky exoplanets is the key uncertainty and deserves quantitative treatment.

This paper is for astrobiologists, SETI researchers, and exoplanet observers planning D/H measurements. It deserves a serious referee. The idea is genuinely new, the calculations are transparent, and the main limitations are explicitly acknowledged. I would send it to review with a request for partial-depletion spectral models and a discussion of natural D/H variation in rocky-planet water.

Referee Report

3 major / 6 minor

Summary. The paper proposes that long-lived technological civilizations relying on deuterium-deuterium (DD) fusion would deplete deuterium in planetary water reservoirs, eventually driving the D/H ratio below the local interstellar medium value of ~16 ppm, and that this sub-ISM D/H anomaly would constitute a durable technosignature. The authors compute depletion timescales under assumed power use (1000 TW, 33% efficiency) for Earth-like ocean masses and initial D/H, and use the SMART radiative transfer model to identify candidate HDO absorption features for JWST (~3.7 μm), HWO (~1.5 μm), and LIFE (~3.7 μm and ~7.5 μm). The paper argues that unlike radio signals or short-lived pollutant technosignatures, the D/H anomaly would persist for eons even after the civilization ceases.

Significance. If the central claim holds, this is a genuinely novel and important technosignature concept: it is durable, requires no active transmitter, and can in principle be tested with near-future observatories. A key strength is that the energy-budget calculation is a transparent forward model built from measured constants (CODATA masses, SMOW D/H, local ISM D/H) and explicitly stated scenario assumptions; there is no fitting to the target result, and the spectral features are generated by an independent radiative transfer code. The paper also clearly identifies where further modeling (clouds, 3D circulation, instrument noise) is needed. The main weaknesses are the unquantified premise about the initial D/H of rocky exoplanet water and the mismatch between the spectral models (which remove all HDO) and the proposed detection threshold (90% depletion), both of which are load-bearing for the paper's central detectability and uniqueness claims.

major comments (3)

[Section 1, Figure 2] The central claim that sub-ISM D/H in planetary water is a fusion technosignature depends on the premise that rocky exoplanet water initially has an Earth-like D/H ratio of ~156 ppm, i.e., an order of magnitude above the ISM value. The paper argues this from pre-stellar ice deuteration, but this is an unquantified extrapolation: if a significant fraction of rocky planets acquire water with near-protosolar D/H (~20 ppm) via nebular gas accretion or D-poor planetesimals, then reaching the 16 ppm threshold requires only ~20% deuterium removal, which could plausibly be produced by atmospheric escape or Rayleigh condensation without any fusion. The paper treats low initial D/H only as shortening the fusion timescale (end of Section 1) and not as a background that could mimic the signal, so the uniqueness of the technosignature is not established.
[Section 3.2, Figure 4] The radiative transfer detectability analysis removes all deuterium-containing water vapor from the atmospheric models ('depleted cases have all deuterium-containing water vapor removed'), while the proposed anomaly threshold is a 90% depletion to sub-ISM D/H (i.e., D/H reduced to ~10% of the SMOW value). Consequently, the predicted transit depth reduction of 4–5 km and the quoted JWST integration times of ~43–100 hours are for a signal that is roughly ten times larger than what would be observed at the threshold, making the detectability claims optimistic. A model with 90% HDO removal should be used to assess whether the 3.7 μm feature is actually detectable in a realistic scenario.
[Section 4] In the Discussion, the paper correctly notes that Rayleigh distillation in cool polar regions can deplete D/H in atmospheric water vapor, but it only evaluates this against an Earth-like initial D/H. Since the sub-ISM threshold is only ~16 ppm, any natural process that drives vapor D/H below the initial water value, such as condensation or atmospheric escape, could produce a sub-ISM vapor signal on worlds with near-protosolar initial D/H. The paper should either model these natural fractionation pathways quantitatively or explicitly restrict the technosignature claim to planets whose initial D/H is confirmed to be Earth-like.

minor comments (6)

[Section 1] There are several typos: 'renewed interested' should be 'renewed interest'; 'new few decades' should be 'next few decades'; 'a only small proportion' should be 'only a small proportion'.
[Section 2.2 and Figure 5] The text specifies an HWO resolving power of 40–70, but Figure 5 and its caption state a resolving power of 70; please make the nominal resolution consistent.
[Section 5] In the Conclusions, 'JSWT' should be 'JWST'.
[References] The spelling of 'Mollière' is inconsistent, appearing as 'Molliere' in Section 3.2 and 'Mollière' in the reference list.
[Section 3.2] The integration-time estimate of 43 hours does not specify the assumed host star magnitude, planet radius, or system distance; please provide these assumptions for reproducibility.
[Figure 2 caption] The caption lists 'Bocklee-Morvan et al. (2015)' while the reference list uses 'Bockelée-Morvan'; please correct the spelling.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the D/H depletion timescale is a forward calculation from stated assumptions and measured constants, and the spectral detectability modeling is independent.

full rationale

The derivation chain is self-contained and non-circular. The central timescale calculation begins from measured external constants (SMOW D/H = 155.76 ppm, CODATA-2018 masses, local ISM D/H = 15.6e-6) and stated scenario assumptions (1000 TW, 33% efficiency, Earth-like ocean mass), then computes the energy per gram of deuterium and the time to deplete ~90% of oceanic deuterium to reach the ISM threshold. No parameter is fitted to the target result, and the resulting ~167 Myr figure is a direct arithmetic consequence. The so-called 'prediction' of anomalously low D/H is not equivalent to an input by construction, because the ISM threshold is an externally measured baseline and the depletion is independently calculated. The paper's assumption that rocky exoplanet water begins with Earth-like D/H is an extrapolation from pre-stellar ice chemistry, not a definitional identification of the conclusion with the premise; the paper explicitly acknowledges that lower initial D/H would shorten the timescale. The spectral detectability analysis uses the SMART radiative transfer model, cited to Meadows & Crisp (1996) and Robinson (2017); although Robinson is a co-author, SMART is an established, independently documented radiative-transfer code, and the HDO/H2O spectral features are physical molecular absorption features, not an output that has been tuned to match the fusion-depletion claim. Other self-citations (Catling et al. 2018; Krissansen-Totton & Catling 2017; Zahnle et al. 2019) are contextual references for biogenic gas searches, climate sensitivity, and solar-system D/H evolution, and none is load-bearing for the central fusion-depletion argument. The paper also candidly notes limitations such as cloudy atmospheres, three-dimensional circulation, and Rayleigh condensation lowering atmospheric D/H; these are acknowledged uncertainties about a real physical background, not circular steps. The central claim therefore has independent content and is not forced by self-citation or by definition.

Assumptions & free parameters 6 free parameters · 6 assumptions · 0 invented entities

The paper introduces no new physical entities. The central calculation is a forward energy budget using measured constants (CODATA masses, SMOW D/H, ISM D/H) and stated scenario choices (1000 TW, 33% efficiency, ocean mass). The main uncertainties are the sociological premise of long-lived high-power fusion use and geophysical assumptions (no deuterium replenishment, Earth-like initial D/H, atmospheric sampling of ocean composition).

free parameters (6)

ET civilization power use = 1000 TW (fiducial)
Assumed to be 10x projected 2100 human demand; used in all timescale estimates. The paper also considers 100 TW cases.
Fusion power conversion efficiency = 33%
Assumed for converting fusion energy to useful power, grounded in current fission and coal plant efficiency; directly scales the time to deplete D.
Initial ocean D/H ratio = 155.76 ppm (SMOW)
Exoplanet oceans are assumed to start with Earth-like D/H; if initial D/H is lower, depletion timescales shorten.
Ocean mass = 1 Earth ocean = 1.426e21 kg; also 0.05, 0.5, 1.5 Mocean
Sensitivity parameter; smaller oceans reach anomalous D/H much faster, e.g., 4% Earth ocean gives ~7 Myr.
HDO removal fraction in spectral models = 100% (all HDO removed)
Chosen for the radiative transfer detectability calculation, not the 90% depletion to ISM; this overstates the expected signal.
Atmospheric water vapor abundance enhancement = 1x and 10x Earth
Spectral models use an Earth-twin and a 10x water-vapor case to test sensitivity.

assumptions (6)

standard math The net DD fusion reaction (D + D + D -> 4He + p + n) and CODATA masses give the stated energy per gram of deuterium.
Methods 2.1; this is the basis of all timescale calculations.
domain assumption A long-lived technological civilization will adopt and maintain DD fusion at ~1000 TW for geological timescales, and will not be limited by waste heat or switch to other energy sources.
Section 1 argues fusion is the most viable long-term energy source; the entire scenario rests on this sociological premise.
domain assumption Deuterium is a closed reservoir in the ocean: no significant replenishment from comets, mantle degassing, or other sources over the depletion timescale.
Needed for monotonic D/H decline; Section 4 defers mantle degassing to future modeling.
domain assumption Initial water on rocky exoplanets has D/H substantially above the local ISM, inherited from D-enriched pre-stellar ices.
Section 1 and Figure 2; establishes that sub-ISM D/H would be anomalous. If false, the technosignature threshold is ambiguous.
domain assumption Atmospheric water vapor D/H reflects the ocean value to within known condensation fractionation (~10-15%), so ocean depletion appears in atmospheric spectra.
Section 4 discusses rainout; needed to connect the modeled ocean depletion to the observable HDO features.
standard math The SMART radiative transfer model and adopted line lists give accurate HDO/H2O spectra for cloud-free atmospheres.
Methods 2.2; spectral detectability results depend on this model.

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Cite this review

Pith. "Pith review of Potential technosignature from anomalously low deuterium/hydrogen (D/H) in planetary water depleted by nuclear fusion technology." pith.science (2026). https://pith.science/paper/3WWFFB6Q

@misc{pith2026241118595,
  author       = {Pith},
  title        = {Pith review of: Potential technosignature from anomalously low deuterium/hydrogen (D/H) in planetary water depleted by nuclear fusion technology},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/3WWFFB6Q}},
  note         = {Machine review of arXiv:2411.18595}
}

abstract

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 $\sim$10 times that projected for humankind next century would deplete the deuterium-hydrogen ratio (D/H) in $\sim$(a few)$\times 10^8$ 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 $\sim10^6$ to $10^7$ 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 $\sim16\times 10^{-6}$ (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 $\mu$m in transmission spectroscopy of Earth-like worlds, $\sim1.5$ $\mu$m (in the wings of the 1.4 $\mu$m water band) in the shorter near-infrared for direct imaging by Habitable Worlds Observatory, and 3.7 $\mu$m or $\sim7.5$ $\mu$m (in the wings of the broad 6.3 $\mu$m bending vibration of water) for concepts like the Large Interferometer for Exoplanets (LIFE).

Figures

Figures reproduced from arXiv: 2411.18595 by the authors.

**Figure 5.** (a) Reflectivity of deuterium-depleted Earth-like worlds, showing a features from HDO near 1.5-1.6 µm. Cases considered are an Earthtwin atmosphere (gray) and an atmosphere where water vapor has been enhanced at 10 times the Earth-twin value (red). Filled swaths show the impact of removing all deuterium-containing water vapor from the atmosphere in each case. (b) The signal-to-noise (SNR) required for one sigma det… view at source ↗

**Figure 6.** (a) Features of deuterium-depleted Earth-like worlds across the mid-infrared. Again, cases considered are an Earth-twin atmosphere (gray) and an atmosphere where water vapor has been enhanced at 10 times the Earth-twin value (red). Filled swaths show the impact of removing all deuterium-containing water vapor from the atmosphere in each case. (b) The signal-to-noise (SNR) required for one sigma detection. A LIFE-lik… view at source ↗

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Reference graph

Works this paper leans on

16 extracted references · 15 canonical work pages

[1]

2018; Schwieterman et al

INTRODUCTION The current telescopic search for life elsewhere focuses mainly on spectroscopic identification of potentially biogenic gases (e.g., CH4 and O2) emitted by microbes or plant-like organisms in extraterrestrial biospheres (Catling et al. 2018; Schwieterman et al. 2018), but technosignatures – detectable evidence of technology that modifies its ...

work page 2022
[2]

because pre-stellar chemistry makes D-enriched water. In general, ices, such as those in comets or moons accreted from comet-like material (e.g., Enceladus), concentrate deuterium in both organic and water molecules because low-temperature reactions in pre-stellar clouds at temperatures of ~10 to ~100 K favor isotopic exchange reactions such as H2O + HD =...

work page 1981
[3]

The annual average power use of humankind in Terawatts (left vertical axis) and the corresponding fraction of global, ice-free land area (right vertical axis) that would need to be covered by solar panels to provide all the power. We note that current human-modified land (infrastructure, crops, and managed land) leaves less than half of land in another st...

work page 2012
[4]

Earth system sensitivity

(c) The additional power use for a population of ~10.4 billion assuming 2021 US per capita levels of power, which is the projected peak global population towards the end of the 21st century. The population projection is from the United Nations, Department of Economic and Social Affairs, Population Division: World Population Prospects 2022, Online Edition,...

work page 2021
[5]

SETI-related ideas

CONCLUSIONS In this paper, we have presented a new idea that very long-lived, advanced extraterrestrial (ET) civilizations using continuous deuterium-deuterium (DD) nuclear fusion could lower the D/H ratio in an ocean to less than the ratio found in natural astronomical sources. Big Bang nucleosynthesis set an initial D/H ratio of 24-27 ppm but the averag...

arXiv 1997
[10]

A technosignature in exoplanetary water of prolonged deuterium-deuterium nuclear fusion would plot below natural astronomical D/H values in the green shaded zone and be anomalous

The deuterium/hydrogen (D/H) ratio in astronomical objects and on Earth. A technosignature in exoplanetary water of prolonged deuterium-deuterium nuclear fusion would plot below natural astronomical D/H values in the green shaded zone and be anomalous. Data sources: Bocklee-Morvan et al. (2015) and references therein for comets; Donahue et al. (1997) for ...

work page 2015
[11]

He + n (3) D+ !He→

METHODS 2.1 Nuclear Fusion Assumptions To calculate the depletion of deuterium in long-term nuclear fusion of an extraterrestrial civilization requires knowing an initial concentration of deuterium in an ocean and the energy release per gram of deuterium. For a practical reference calculation, we assume an initial D/H ratio of Earth’s ocean. We then assum...

work page 1970
[14]

Spectra emphasize the O-D stretching vibration of HDO near 3.7 µm

This figure demonstrates the possibility of using transit spectroscopy to detect the effect of deuterium depletion in water vapor for an Earth-twin and a world with 10 times enhanced atmospheric water vapor, which could be the case for a warm Earth-like world near the habitable zone inner edge. Spectra emphasize the O-D stretching vibration of HDO near 3....

work page 2022

Show all 16 references

[15]

and future telescopes (Figures 5 and 6). In future measurements of D/H, it may be important to consider possible climatic influences on the D/H in atmospheric water vapor, specifically the preferential rainout of relatively isotopically heavy ice, rain or snow that might lower...

2015
[1983]

Lithium could be extracted from seawater by electrolysis (Yang et al

of which 6Li is 7.42% (James & Palmer 2000), i.e., a mass of (0.17´10-6) ´0.0742´ (1.426´1021 kg/ocean) ~ 1.8´1012 kg 6Li or ~18,000 million tonnes. Lithium could be extracted from seawater by electrolysis (Yang et al

2000
[1988]

and orbit (Vandaele et al. 2019). Molliere and Snellen (2019) calculate that 1 night of Extremely Large Telescope observing time with 𝜆/Δ𝜆 ∼ 100,000 at ~3.7 µm would be sufficient to measure HDO on Proxima Cen b if it has an Earth-like atmosphere with Earth-like D/H ratio in i...

2019
[2011]

would rapidly produce an anomalous D/H ratio, e.g., after only ~7 Myr for 4% of Earth’s ocean mass. Even modest energy consumption (such as the that predicted for humankind with a population predicted for ~2100 and 2021 American per capita power use) would produce an anomalous...

2021
[2016]

but would cause intolerable disruption to ecosystems from the huge land use. The size can be seen from scaling up an order of magnitude the land use in Figure 1, noting that over half of the land free of ice sheets is unavailable because of human-occupation or management. Nucl...

2011
[2018]

Each DT fusion reaction releases 2.8´10-12 J

followed by 6Li-enrichment. Each DT fusion reaction releases 2.8´10-12 J. Because each atom of 6Li generates one tritium atom, the amount of energy per gram of 6Li is (2.8´10−12 J ´ NA)/( 6.015125 g/mol 6Li) = 2.8 ´1011 J, where NA is Avogadro’s number, 6.022´1023. For an uppe...

2005
[2021]

human power equivalents

or chlorofluorocarbons (CFCs) (Haqq-Misra et al. 2022; Seager et al. 2023), but as trace gases they are generally undetectable with present or near-term technology. Also, such gases from immature civilizations would probably be extremely short-lived compared to the signal that...

2010
[2024]

are possible. But on rocky worlds, initial D/H in water may generally be about an order of magnitude higher than gas giant hydrogen and perhaps Earth-like because of inheritance from pre-stellar icy material. Of course, some rocky planets may have even more elevated D/H in the...

2017

Pith tools

Reviewed August 12, 2026 · model on record in the stance chip above.

[1] [1]

2018; Schwieterman et al

INTRODUCTION The current telescopic search for life elsewhere focuses mainly on spectroscopic identification of potentially biogenic gases (e.g., CH4 and O2) emitted by microbes or plant-like organisms in extraterrestrial biospheres (Catling et al. 2018; Schwieterman et al. 2018), but technosignatures – detectable evidence of technology that modifies its ...

work page 2022

[2] [2]

because pre-stellar chemistry makes D-enriched water. In general, ices, such as those in comets or moons accreted from comet-like material (e.g., Enceladus), concentrate deuterium in both organic and water molecules because low-temperature reactions in pre-stellar clouds at temperatures of ~10 to ~100 K favor isotopic exchange reactions such as H2O + HD =...

work page 1981

[3] [3]

The annual average power use of humankind in Terawatts (left vertical axis) and the corresponding fraction of global, ice-free land area (right vertical axis) that would need to be covered by solar panels to provide all the power. We note that current human-modified land (infrastructure, crops, and managed land) leaves less than half of land in another st...

work page 2012

[4] [4]

Earth system sensitivity

(c) The additional power use for a population of ~10.4 billion assuming 2021 US per capita levels of power, which is the projected peak global population towards the end of the 21st century. The population projection is from the United Nations, Department of Economic and Social Affairs, Population Division: World Population Prospects 2022, Online Edition,...

work page 2021

[5] [5]

SETI-related ideas

CONCLUSIONS In this paper, we have presented a new idea that very long-lived, advanced extraterrestrial (ET) civilizations using continuous deuterium-deuterium (DD) nuclear fusion could lower the D/H ratio in an ocean to less than the ratio found in natural astronomical sources. Big Bang nucleosynthesis set an initial D/H ratio of 24-27 ppm but the averag...

arXiv 1997

[6] [10]

A technosignature in exoplanetary water of prolonged deuterium-deuterium nuclear fusion would plot below natural astronomical D/H values in the green shaded zone and be anomalous

The deuterium/hydrogen (D/H) ratio in astronomical objects and on Earth. A technosignature in exoplanetary water of prolonged deuterium-deuterium nuclear fusion would plot below natural astronomical D/H values in the green shaded zone and be anomalous. Data sources: Bocklee-Morvan et al. (2015) and references therein for comets; Donahue et al. (1997) for ...

work page 2015

[7] [11]

He + n (3) D+ !He→

METHODS 2.1 Nuclear Fusion Assumptions To calculate the depletion of deuterium in long-term nuclear fusion of an extraterrestrial civilization requires knowing an initial concentration of deuterium in an ocean and the energy release per gram of deuterium. For a practical reference calculation, we assume an initial D/H ratio of Earth’s ocean. We then assum...

work page 1970

[8] [14]

Spectra emphasize the O-D stretching vibration of HDO near 3.7 µm

This figure demonstrates the possibility of using transit spectroscopy to detect the effect of deuterium depletion in water vapor for an Earth-twin and a world with 10 times enhanced atmospheric water vapor, which could be the case for a warm Earth-like world near the habitable zone inner edge. Spectra emphasize the O-D stretching vibration of HDO near 3....

work page 2022