In-situ detection of Europa’s water plumes is harder than previously thought
Bibliographic record
Abstract
Europa’s subsurface ocean is a potential candidate for life in the outer solar system. It is thought that plumes may exist which eject ocean material out into space, which may be detected by a spacecraft flyby. Previous work on the feasibility of these detections has assumed a collisionless model of the plume particles. New models of the plumes including particle collisions have shown that a shock can develop in the plume interior as rising particles collide with particles falling back to the moon’s surface, limiting the plume’s altitude. These models also assume a Laval nozzle-like vent which results in a colder plume source temperature than in previous studies, further limiting the plume’s extent. We investigate to what degree the limited extent of the shocked plumes reduces the ability of the JUICE spacecraft to detect plume H2O molecules. Results show that the region over Europa’s surface within which plumes would be separable from the H2O atmosphere by JUICE (the region of separability) is reduced by up to a half with the collisional model compared to the collisionless model. Putative plume sources which are on the border of the region of separability for the collisionless model cannot be separated from the atmosphere when the shock is considered for a mass flux case of 100 kgs−1. Increasing the flyby altitude by 100 km such that the spacecraft passes above the shock canopy results in a reduction in region of separability by a third, whilst decreasing the flyby altitude by 100 km increases the region of separability by the same amount. We recommend flybys pass through or as close to the shock as possible to sample the most high-density region. If the spacecraft flies close to the shock, the structure of the plume could be resolvable using the neutral mass spectrometer on JUICE, allowing us to test models of the plume physics and understand the underlying physics of Europa’s plumes. As the altitude of the shock is uncertain and dependent on unpredictable plume parameters, we recommend flybys be lowered where possible to reduce the risk of passing above the shock and losing detection coverage, density and duration.
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 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".