Space environment challenges with the tunable Fabry-Pérot etalon for the JWST fine guidance sensor
Bibliographic record
Abstract
The Fine Guidance Sensor (FGS) on the James Webb Space Telescope (JWST) has a science observing capability that was to be provided by a tunable Fabry-Pérot etalon incorporating dielectric coated etalon plates with a small vacuum gap and piezoelectric actuators (PZTs). The JWST etalon was more challenging than our existing ground-based operational systems due to the low-order gap, the extremely wide waveband and the environmental specifications. Difficulties were encountered in providing the required performance due to variability in the mechanical gap after exposure to the vibration, shock and cryogenic cycling environments required for the JWST mission. The risks associated with operating the flight model etalon in the space environment, along with changes in scientific priorities, resulted in the etalon being replaced by the grism-based Near-Infrared Imager and Slitless Spectrograph (NIRISS). We describe here the performance of the etalon system and the unresolved risks that contributed to the decision to change the flight instrument.
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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 | 0.003 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".