Flow dynamics and thermal effects in the ejecta of the multiple-layered Kotka crater on Mars
Bibliographic record
Abstract
The multiple-layered ejecta surrounding crater Kotka (east of Elysium Mons) are studied using imagery and physical modelling. This particular crater was chosen not only because its ejecta are well preserved, but more importantly because the impact area is surrounded by mounds, which provide a means of determining the velocity of the ejecta based on run-up criteria. If the ejecta passed over a mound of a certain height, the velocity was greater than that necessary to rise up that height, while the presence of a shadow beyond the mound indicates a velocity lower than that limit. Top ejecta flow velocities were found to vary between 25 m/s and 80 m/s. Velocities are also determined based on the length of the jump against craters rims, a criterion that provides an estimate of the velocity, rather than a limit, and are found to be compatible with those estimated with run-up criteria. We find that a first train of ejecta travelling at high velocity was capable of overcoming many mounds. A peculiar rampart often visible at the foot of many of the mounds is interpreted as a frozen hydraulic jump indicating a phase in which the ejecta were about to stop. The velocity of the ejecta was found to decrease with distance from the rim but not as fast as a constant friction model would suggest, indicating effective friction that increases with distance, and more complex rheology than pure frictional behavior. The velocities indicate a rheology for the fluidized ejecta in which the debris material was completely fluidized, to the point that the friction coefficient decreased by one to two orders of magnitude compared to the one of fragmented rock. Our conceptual model is that the ejecta material initially contained a large amount of solid ice that was fluidized and vaporized by the impact. The chains of pits visible in the ejecta, interpreted as fossilized bubbles of volatiles released through the hot fluidized material, confirm that high temperatures were reached during impact, as also indicated by analytical estimates. Fluidization altered the rheology of the ejecta in a way that has yet to be understood.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot 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.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".