On The Habitability Of An Impacted Young Earth 
Bibliographic record
Abstract
The formation of life on Earth is generally understood to have required the presence of liquid water, as well as an atmosphere within which the feedstock molecules — such as HCN — for more complex biomolecules are able to form. From the precipitation of these simple molecules, RNA can be built. The thermal profile and surface pressure of early Earth that was necessary for a liquid water cycle may have been created by a large impact, or series of larger impacts, following the formation of our Moon. Models which feature the consequences of very large impacts (e.g. Zahnle 2020) have dense, hydrogen-rich atmospheres that can be conductive to both the formation of HCN and a temperate surface temperature under the faint young Sun. In this work, we developed detailed self-consistent thermochemical equilibrium PT structures for post-large-impact atmospheres. We use a 1D radiative-convective equilibrium modelling code to obtain these thermal profiles and equilibrium chemistry. We found that the 5 optically thick cases for a dry atmosphere have a self-consistent surface temperature that is 742K on average; however, without the collisional opacity from H2 molecules contributing to the radiative transfer, this self-consistent surface temperature is an average of 394K. For a wet atmosphere, these values are 842K and 568K, respectively. Our current results suggest that, in the work of Zahnle et al. (2020), early post-impact HCN yields were computed for atmospheres that are initially too hot for the necessary liquid surface water and too hot for these molecules to be stable.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
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".