Ion acceleration at Mars Bow Shock - Results from MAVEN
Bibliographic record
Abstract
The bow shock of Mars provides a compelling example of a mass-loaded, supercritical shock. A key challenge in space plasma physics is understanding the mechanisms of particle acceleration that occur at collisionless shocks. Due to extensive studies, the terrestrial foreshock is often considered a benchmark for interactions between planetary magnetospheres and the solar wind. The MAVEN mission at Mars is offering a wealth of data, simultaneously opening a window to study the Martian foreshock in detail. In this context, we present new measurements of velocity distribution functions of suprathermal protons upstream of Mars' bow shock. We identify backstreaming beams aligned (FAB) and misaligned with the interplanetary magnetic field (IMF) direction for various shock geometries. FAB bulk velocities are found to be well-distributed in relation to the shock speed. Our analysis reveals that, compared to their terrestrial counterparts, Martian FABs exhibit slower sunward motion. Additionally, it appears that these FABs originate from a shock region where the IMF lines form an angle of 20-50 degrees with the shock normal— a smaller source region than that of Earth's bow shock. These findings rule out specular reflection as the mechanism behind beam production. Typically, terrestrial FABs are produced through a quasi-adiabatic process that preserves the first invariant to some extent. In contrast, the new Martian observations provide a valuable comparison between the foreshocks of Earth and Mars, shedding light on key differences and enhancing our understanding of these planetary phenomena.
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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 | 0.001 |
| 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 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".