Narrowing the List of Potential Biosignature Gases for the Search for Life on Exoplanets
Bibliographic record
Abstract
Thousands of exoplanets orbit nearby stars and the possibility that one of them may contain extraterrestrial life should be explored. Earth’s atmospheric spectrum has a few characteristic gases (O2,CH4,N2O) and others are posited to appear on exo-Earths (e.g., dimethyl sulfide and CH3Cl). Seager et al. (2016) provided a list of potential biosignatures that could be examined to allow for the further narrowing of gases that could be valuable in determining exoplanet habitability and signs of life. Here, we build on this previous work by examining gas stability and volatility in Earth-like temperatures and pressures. This allows us to further refine the number of potential gases that are useful. We draw and expand upon two viable biosignature gases: Methyl chloride (CH3Cl) and dimethyl sulfide (CH3SCH3or DMS). The biggest limitation is this: the biochemistry and ecology of a potential biosignature vary even among Earth-life and so cannot be assumed to be the same on other worlds.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.004 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".