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Record W3140637841 · doi:10.1111/1462-2920.15494

Mars' surface is not universally biocidal

2021· article· en· W3140637841 on OpenAlexfundno aff
John E. Hallsworth

Bibliographic record

VenueEnvironmental Microbiology · 2021
Typearticle
Languageen
FieldPhysics and Astronomy
TopicPlanetary Science and Exploration
Canadian institutionsnot available
FundersBiotechnology and Biological Sciences Research CouncilJet Propulsion LaboratoryDirectorate for Biological SciencesAmes Research CenterUniversidade de São PauloLatvijas UniversitateNational Aeronautics and Space AdministrationCalifornia Institute of TechnologyQueen's University BelfastQueen's University
KeywordsMars Exploration ProgramRegolithAstrobiologyBiologyExtremophileMicroorganismBacteriaPaleontology

Abstract

fetched live from OpenAlex

Summary The Mars surface/near‐surface is often considered to be biocidal. Here, diverse lines of evidence are presented indicating that some terrestrial microbes can survive the in‐situ conditions albeit in an inactive state. For the purposes of planetary protection, it is important to consider what we mean by a planetary ‘surface’; this term has qualitatively distinct definitions fordifferent scientific disciplines, and can also have different meanings from a humanviewpoint versus that of a microbial cell. Most microbial cells spores or other cells deposited on Mars, even those that initially fall on the outward‐facing part of the absolute surface, will fall within pores of the regolith or become covered by its dust. They are, therefore, protected from ultra‐violet radiation. Desiccating conditions and low temperatures (−40 to −70°C) can act to preserve rather than kill all microbes, potentially maintaining cellular viability – especially for certain extremophiles – over geological timescales. Whereas salts are ubiquitous on Mars, many terrestrial microbes are highly tolerant to NaCl and other salts, and these substances (including potentially inhibitory chaotropes such as MgCl 2 and perchlorates) cannot access cells in the absence of a liquid milieu. Whereas the Mars regolith is nutrient‐deplete and conditions may be acidic in places, oligotrophic conditions per se are not biocidal and many terrestrial microbes can thrive in acidic conditions (some acidophiles can proliferate at or below pH 0). The low temperatures of Mars' surface are not conducive to metabolic activity, but the biophysical sophistication and robust stress biology of many terrestrial microbes, and the protection afforded by Martian conditions, are likely to ensure the long‐term viability of some extremophilic microbes if transported to Mars.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesInsufficient payload (model declined to judge)
Consensus categoriesInsufficient payload (model declined to judge)
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: Bench or experimental
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.192
Threshold uncertainty score0.998

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0030.003

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.

Opus teacher head0.005
GPT teacher head0.170
Teacher spread0.165 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; both teacher heads agree on what is shown here.

Study designBench or experimental
Domainnot available
GenreEmpirical

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".

Quick stats

Citations21
Published2021
Admission routes1
Has abstractyes

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