Beyond Bulk Chemistry: Enhancing the Science Return of Landed In Situ X-ray Spectrometers
Bibliographic record
Abstract
X-ray fluorescence (XRF) spectroscopy has long served as a cornerstone analytical technique in planetary surface exploration, enabling high-precision compositional analyses of planetary materials in situ. On Mars, two prominent XRF instruments — the Alpha Particle X-ray Spectrometer (APXS) aboard Curiosity and the Planetary Instrument for X-ray Lithochemistry (PIXL) aboard Perseverance — have demonstrated that the capabilities of landed XRF instruments extend beyond the quantification of bulk chemistry. Native Sulfur on MarsAPXS has performed ~1700 compositional analyses since Curiosity landed in Gale crater in 2012. While APXS traditionally derives bulk rock and soil compositions, systematic advancements have been made that enable the assessment of distinct features on the sub-cm scale, smaller than the APXS field of view (e.g., [1]). This advancement, combined with the capability to characterize light‑element (i.e., Z
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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 | 0.004 | 0.008 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.005 | 0.011 |
| Open science | 0.002 | 0.004 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.017 | 0.010 |
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".