Mineralogically Diverse and Salt‐Rich Regolith in Jezero Crater Characterized Using X‐Ray Spectroscopy
Bibliographic record
Abstract
Abstract The Planetary Instrument for X‐ray Lithochemistry (PIXL) onboard the Perseverance rover has characterized the composition of Martian regolith at a scale of hundreds of microns using micro‐focus X‐ray fluorescence spectroscopy. PIXL data reveal a diverse population of regolith grains with distinct spectral, chemical, and crystallographic properties, through which we identified the mineralogy of individual regolith components. Olivine, phyllosilicate, carbonate‐bearing phases, Cr‐Ti‐spinel, plagioclase, and Fe‐sulfate are all inferred from the data, and potential local and regional bedrock sources are proposed for each. PIXL also inspected dust and soil components, which were found to be geochemically similar to analogous components characterized elsewhere by preceding missions. Unlike other sites, regolith on the western fan front of Jezero crater contains fewer sulfates, but is highly enriched in Cl (up to 2.0 ± 0.5 wt. %), which likely includes chlorides, chlorates, and/or perchlorates. PIXL also finds evidence of hydration in the regolith, potentially carried by salts, as interstitial water, and/or in adsorbed phases. PIXL's observations of diverse amorphous and crystalline components, multiple styles of aqueous alteration, and enrichments of brine‐forming salts provide exciting new justification for the return of a Martian regolith sample to Earth for further study.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".