{"id":"b6cfc873-7650-4e71-8a12-2b822fa3391b","arxiv_id":"2507.00933","paper_version":1,"verdict":"ACCEPT","confidence":"HIGH","novelty_score":3.0,"correctness_risk":"low","formal_verification":"none","parameter_count":0,"one_line_summary":"This review of JWST rocky exoplanet observations finds no confirmed atmospheres and sets a five scale height precision target for future transmission spectroscopy.","lead":"Kreidberg and Stevenson review the first JWST results on rocky exoplanet atmospheres and conclude that none have been definitively detected, with hot daysides that match bare rocks or very thin atmospheres. They propose a 'five scale height challenge' as the next precision goal for transmission spectroscopy.","discovery_kind":"review","skeptic_critique":{"model":"deepseek-v4-flash","headline":"No significant objection identified: the paper's central synthesis is appropriately caveated, and the quantitative ensemble average is not load-bearing to its conclusion.","rationale":"The paper is a balanced, well-caveated synthesis rather than a new measurement. Its central message matches the cited literature and its own explicit assumptions. The reader's flagged weakness—heterogeneous ensemble with systematics in LHS 1478b and model degeneracies for TRAPPIST-1b/c—is real but secondary: the paper's main conclusion about hot daysides and the rarity of thick CO2 atmospheres is driven by the most precise individual planets and is stated with appropriate caveats. Even if the ensemble average shifted, the ACCEPT verdict would stand. I therefore report no significant objection, while recommending a simple robustness calculation as due diligence.","tokens_in":15852,"tokens_out":11161,"duration_ms":206509,"concrete_test":"As a worthwhile robustness check, recompute the ensemble statistics after excluding LHS 1478b and treating TRAPPIST-1b's two bandpasses as correlated measurements, then compare the resulting mean and Bond albedo to the reported 0.95±0.01 and 0.15±0.03; if the values shift by more than the quoted uncertainties, the paper should note the sensitivity, but the qualitative conclusion is unlikely to change.","verdict_should_be":"UNCHANGED","load_bearing_attack":"No significant objection identified. The central claim is a review-level synthesis of published JWST results and is explicitly conditional: the abstract limits the 'thick, CO2-rich atmospheres ruled out' statement to cloud-free models, and the Discussion extends this caveat by noting that realistic clouds remain to be explored while citing TRAPPIST-1c's cloud-inclusive constraint. The new quantitative element, the 0.95±0.01 × TB,max ensemble average and Bond albedo 0.15±0.03, is illustrative rather than load-bearing: the qualitative conclusion that hot daysides favor bare rocks or thin atmospheres is supported independently by the most precise individual measurements (LTT 1445 Ab, GJ 1132b, GJ 486b, GJ 367b), which the paper identifies as the drivers. The paper itself flags LHS 1478b's systematics and TRAPPIST-1b/c degeneracies, so the heterogeneity of the ensemble is acknowledged rather than hidden. The transmission claim that no atmospheres have been definitively detected is a fair characterization of the cited evidence, including L98-59d's tentative features. The five-scale-height challenge is a goal, not an empirical claim. No internal inconsistency or unsupported step rises to the level of a load-bearing objection.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper is a review-style synthesis, by two leading observers, of the first JWST results on rocky exoplanet atmospheres. Section 1 covers transmission spectroscopy: the authors find that current spectra, though the most precise ever obtained for rocky planets, are sensitive only to cloud-free, water-rich (mu = 18 g/mol) compositions; none of the published spectra reaches the precision needed to detect features in N2-, O2-, or CO2-dominated atmospheres, and the tentative detections (GJ 486b, GJ 1132b, L 98-59d, LHS 1140b) are either consistent with stellar contamination or not yet confirmed. Section 2 covers thermal emission: seven planets have published eclipse measurements, the daysides are hot (ensemble weighted mean TB = 0.95 +/- 0.01 x TB,max, chi^2_nu = 1.9, 7 dof), which the authors interpret as consistent with bare rocks or low surface pressure (< 10 bar) atmospheres, and thick CO2-rich atmospheres are generally disfavored assuming cloud-free models. Section 3 discusses implications for volatile inventories and escape, proposes a 'five scale height challenge' for future transmission spectroscopy, and notes the limits of current data, including stellar contamination and cloud degeneracies.","tokens_in":16003,"tokens_out":28772,"duration_ms":292818,"significance":"The synthesis, if accepted, provides a coherent and timely status report on a flagship JWST science theme. The paper's strengths are its explicit conditionality (the CO2 exclusion is tied to cloud-free models, with the TRAPPIST-1c cloudy case cited), its transparent reporting of the ensemble statistic (chi^2_nu and dof are given, and the paper notes the result is driven by the four hottest, most precise planets), its public data release of binned spectra on Zenodo, and its concrete, falsifiable proposal (the five scale height challenge). The review is faithful to the cited literature and appropriately cautious about tentative detections and systematics. Its principal limitations are inherent to a synthesis: the ensemble average weights heterogeneous measurements equally, and the quantitative elements (the 0.95 +/- 0.01 ratio and the derived albedo) are illustrative rather than decisive, since the qualitative conclusion is supported independently by the most precise individual eclipses.","major_comments":[{"comment":"The paper's only quantitative derivation in the Discussion states that the mean brightness-temperature ratio 0.95 +/- 0.01 x TB,max 'corresponds to' a Bond albedo of AB = 0.15 +/- 0.03. The conversion is not shown in the text. Using the standard relation AB = 1 - (TB/TB,max)^4 in the Mansfield et al. (2019) framework that is cited for the normalization (Materials and Methods, Eq. 6 of ref. 107) yields AB about 0.19 +/- 0.03, which is roughly 0.04 higher than the quoted central value. If a bandpass color correction or a non-unity surface emissivity is responsible for the difference, that assumption should be stated; otherwise the value should be corrected or re-derived. This is a local issue that does not change the qualitative bare-rock interpretation, but as printed the reported albedo is not reproducible from the information given.","section":"Section 3 Discussion; Materials and Methods"},{"comment":"The weighted average is quoted with chi^2_nu = 1.9 and 7 degrees of freedom, which is consistent with 8 data points and 1 fitted parameter, i.e., the fit treats the two TRAPPIST-1b bandpass measurements (12.8 and 15 microns) as independent and includes LHS 1478b even though its eclipse measurement is flagged as affected by instrument systematics. If the two TRAPPIST-1b points are not independent (the 12.8 and 15 micron eclipse depths are analyzed jointly in Ducrot et al. 2025), the effective number of degrees of freedom and the reported consistency ('1.8 sigma') change. Please state the assumed covariance and, as a robustness check, recompute the ensemble mean and albedo with TRAPPIST-1b collapsed to a single point and with LHS 1478b excluded.","section":"Section 2 Thermal emission, Fig. 4"}],"minor_comments":[{"comment":"The phrase 'consistent within 1.8 sigma' is ambiguous: it could mean the maximum residual of any individual planet from the weighted mean, or the normal-equivalent significance of the chi^2_nu = 1.9 goodness-of-fit (7 dof); please state explicitly which quantity the 1.8 sigma refers to.","section":"Section 2, Fig. 4 caption"},{"comment":"The comparison between GJ 341b (11 ppm average uncertainty) and GJ 486b (3.8 scale heights average uncertainty) should state that both figures are computed at the same uniform 50 nm binning, so the reader can compare them directly.","section":"Section 1 Transmission"},{"comment":"Many journal names and author names are corrupted in the reference list (e.g., 'A@AND@A' instead of 'A&A' in refs 5, 6, 13, 15, 26, 33, 41, 45, 47, 59, 62, 68, 72, 75, 80, 91, 94, 101, 103, 105; 'RAS T ech. Instruments' in ref 93; 'Y aeger' in refs 40 and 51); these must be corrected in the published version.","section":"References"},{"comment":"The caption says 'The gray regions, which are 5H in height,' but the figure appears to show a single gray band labeled 5 scale heights; please make the plural/singular usage consistent and clarify whether the band marks the vertical (relative transit depth) scale or the horizontal scale.","section":"Fig. 3 caption"}],"recommendation":"minor_revision","confidential_remarks":"This is a well-crafted review by leaders in the field, appropriate for the journal; the qualitative conclusions are solid and consistent with the literature. The new quantitative elements are modest and are the only parts that need scrutiny: the albedo conversion appears internally inconsistent as printed, and the ensemble statistics rest on an independence assumption for the two TRAPPIST-1b points that should be stated. Both are local and fixable. No concerns about novelty disclosure or citation practice; the reference list is comprehensive, though the arXiv text shows clear extraction artifacts. I would be comfortable with minor revision rather than major revision because no load-bearing part of the review's central message is in question."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Know this: the paper is a review, not a discovery paper. The genuinely new bits are the ensemble brightness temperature average (0.95 +- 0.01 TB,max) and the \"five scale height challenge\" as a community goal. Both are modest, but the review as a whole is careful, well-caveated, and likely to be cited as the field's status snapshot.\n\nWhat it does well: The survey of transmission spectra is accurate and balanced. The treatment of stellar contamination is appropriately prominent; it's the real bottleneck and they say so. The thermal emission section carefully lays out the degeneracies for TRAPPIST-1b and c, and flags LHS 1478b's systematics. The binned spectra are on Zenodo, a small but real reproducibility gesture. The five scale height challenge is concrete and testable, which is more than most perspective pieces offer.\n\nWhere it's soft: The ensemble fit is the weakest quantitative step. It's a weighted average of seven measurements with very different systematics, and the authors themselves note it's driven by the four hottest planets. The Bond albedo derived from it (0.15 +- 0.03) inherits that heterogeneity. The \"less than 10 bar\" bound is explicitly tied to cloud-free models, and the discussion does acknowledge that, but readers may miss the caveat. The closing sentence about JWST finding atmospheres if they exist is cheerleading, not analysis. None of this undermines the central claim, because the qualitative picture (hot daysides, no thick CO2) is supported by the most precise individual measurements, not just the average.\n\nThe stress-test note is right: there's no circularity or load-bearing flaw. The review is a fair representation of the published literature.\n\nWho it's for: any exoplanet person, particularly those planning JWST proposals. It deserves a serious referee. I'd accept it with minor comments asking to soften the Bond albedo claim and the closing sentence.","headline":"A solid, well-caveated review that will become the field's status-quo citation; the ensemble average is illustrative, not load-bearing.","tokens_in":16562,"tokens_out":1873,"would_cite":true,"duration_ms":21308,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"The first JWST surveys of rocky exoplanets have not yet found a single confirmed atmosphere, and the thermal emission data point toward bare rocks or very thin atmospheres on the hot planets observed so far.","keywords":["rocky exoplanet atmospheres","JWST","transmission spectroscopy","thermal emission","secondary eclipse","M-dwarf planets","carbon dioxide atmospheres","stellar contamination"],"falsifier":"A JWST/MIRI eclipse observation of a hot rocky planet showing a 15-µm brightness temperature well below the $0.95 \\pm 0.01$ bare-rock ensemble average together with a hotter 12.8-µm point would indicate a thick CO$_2$ atmosphere with a thermal inversion, falsifying the paper's no-thick-atmosphere conclusion. The joint 15-µm phase curve of TRAPPIST-1b and c described in the paper would also falsify the bare-rock picture for at least one planet if it detects substantial day-night heat redistribution.","tokens_in":15603,"feed_emoji":"🪐","tokens_out":17505,"duration_ms":172113,"temperature":0.7,"pith_summary":"The paper synthesizes the first JWST results on rocky exoplanets and argues that, despite milestones such as the most precise transmission spectra to date and the first thermal emission detections of rocky worlds below 800 K, no atmosphere has been conclusively detected. In transmission, the best spectra rule out hydrogen-rich and cloud-free water-rich compositions, but the features of heavier, more plausible atmospheres remain below the noise, and some tentative detections may be stellar contamination. In thermal emission, the seven measured planets all show daysides close to the theoretical maximum for a zero-albedo bare rock, with an ensemble average of $0.95 \\pm 0.01$ times that maximum, consistent with bare rock surfaces or atmospheres thinner than about 10 bar. The paper therefore concludes that thick, CO$_2$-rich atmospheres are generally absent from the hot, close-in sample, which would imply a limited initial volatile inventory or very early atmospheric escape. This matters because whether small planets retain atmospheres is the central unknown for their habitability.","feed_headline":"JWST's rocky exoplanets look like bare rock, not Venus","feed_subtitle":"Early eclipses of seven hot planets find no thick CO2 air; cooler worlds are the next target.","key_machinery":"The central quantitative object is the dayside brightness temperature measured during a secondary eclipse, when the planet passes behind its star, normalized to the theoretical maximum for a zero-albedo bare rock, $T_{\\mathrm{B,max}}$. The paper compares seven such measurements against models of full heat redistribution and of a 10-bar pure CO$_2$ atmosphere, using the heat-redistribution parameter $f$: a bare rock with no day-to-night transport has a hot dayside, while a thick atmosphere redistributes heat and cools the dayside. In transmission, the matching machinery is the atmospheric scale height $H$, the characteristic vertical length of the atmosphere, which shrinks as mean molecular weight rises; all spectra are normalized in units of $H$ to compare feature amplitudes, and the proposed 'five scale height challenge' sets the precision target for detecting CO$_2$ in a nitrogen-dominated atmosphere at 4.3 µm.","core_discovery":"The central claim is that JWST's first look at rocky exoplanets has produced precise spectra yet no definitive atmospheric detection. The published transmission spectra are mostly flat or ambiguous: flat spectra for TOI-836b, LHS 475b, GJ 341b, and L 98-59c cannot distinguish clouds, high-mean-molecular-weight atmospheres, or airless surfaces, while tentative water features on GJ 486b and GJ 1132b and a possible sulfur feature on L 98-59d are either marginal or plausibly caused by unocculted starspots. Emission measurements of seven planets—TRAPPIST-1b and c, GJ 1132b, GJ 486b, GJ 367b, LTT 1445Ab, and LHS 1478b—show hot daysides near the zero-albedo bare-rock maximum; the ensemble is consistent with a relative brightness temperature of $0.95 \\pm 0.01$ times that maximum, which corresponds to a Bond albedo of $0.15 \\pm 0.03$ if the planets are airless. These data are compatible with bare rocks or atmospheres with surface pressure below about 10 bar and, assuming cloud-free atmosphere models, generally rule out thick CO$_2$-rich atmospheres; for TRAPPIST-1c, Venus-like CO$_2$ compositions are disfavored even when sulfuric-acid clouds are included. The absence of strong CO$_2$ features leads the authors to infer a limited initial volatile inventory or early atmospheric escape, and they frame a 'five scale height challenge' as the precision needed to detect CO$_2$ in a nitrogen-rich atmosphere.","pith_inferences":["We infer that if the bare-rock pattern holds for additional hot rocky planets, the default outcome of formation around M dwarfs at high irradiation is severe volatile depletion, which would shift the search for habitable atmospheres toward cooler planets and earlier-type host stars than the current sample.","A testable extension the paper does not develop: measuring eclipse color ratios, such as 12.8 versus 15 µm, can separate a bare rock from a CO$_2$ emission feature produced by a thermal inversion, so even one additional multi-band eclipse of a hot rocky planet would sharpen the ensemble constraint.","We infer that the five-scale-height challenge is achievable on the brightest targets within a few JWST cycles; if those deeper transmission spectra still show no molecular features, the conclusion that rocky M-dwarf planets rarely retain atmospheres would be substantially strengthened.","If thick CO$_2$ atmospheres are genuinely absent while CO$_2$ is expected to resist escape, then the volatile budget of rocky planet formation may be the binding constraint, and atmospheric escape models would need to explain how even heavy species are removed before a thick atmosphere can accumulate."],"forward_implications":["If the ensemble result holds, thick CO$_2$-rich atmospheres like Venus's are rare or absent on hot, close-in rocky planets, implying that large volatile inventories were either never delivered or were lost very early in these planets' lives.","The bare-rock interpretation implies a low Bond albedo of $0.15 \\pm 0.03$ for the sample, consistent with dark basaltic surfaces, so thermal emission is a relatively efficient probe for the hottest rocky planets.","Future atmospheric detections are more likely for cooler planets on the atmosphere-retaining side of the cosmic shoreline and for transmission spectra pushed to the five-scale-height precision level, rather than for more eclipses of these hot targets.","Stellar contamination from unocculted starspots and faculae, not instrument noise, is emerging as the main obstacle to precise transmission spectra of M-dwarf rocky planets; back-to-back transit observations of multi-planet systems offer a promising correction.","Flat transmission spectra alone cannot distinguish high-altitude clouds, high-mean-molecular-weight atmospheres, or bare rock surfaces, so multi-wavelength eclipse photometry and phase curves are needed to break this degeneracy."],"supporting_citations":[{"why":"It supplies the 10-bar pure-CO$_2$ radiative-convective model tracks against which the measured brightness temperatures are compared.","marker":"(66)"},{"why":"It is the first JWST thermal emission detection of a rocky planet, TRAPPIST-1b, anchoring the emission sample.","marker":"(73)"},{"why":"It is the TRAPPIST-1c eclipse measurement that rules out a thick CO$_2$ atmosphere, a key support for the no-thick-atmosphere claim.","marker":"(74)"},{"why":"It combines 12.8 and 15 µm TRAPPIST-1b eclipse data that define the bare-rock versus CO$_2$-emission degeneracy.","marker":"(75)"},{"why":"It provides the GJ 1132b thermal emission measurement included in the ensemble average and the no-thick-atmosphere conclusion.","marker":"(76)"},{"why":"It provides the GJ 486b eclipse measurement included in the ensemble average and the no-thick-atmosphere conclusion.","marker":"(77)"},{"why":"It presents the GJ 367b full-orbit phase curve showing no day-night heat redistribution, the strongest bare-rock case.","marker":"(78)"},{"why":"It supplies the LTT 1445Ab thermal emission spectrum included in the ensemble.","marker":"(79)"},{"why":"It provides the LHS 1478b eclipse measurement included in the ensemble despite instrument systematics that the paper flags.","marker":"(80)"},{"why":"It defines the Transit Light Source Effect, the stellar-contamination mechanism invoked to explain why tentative transmission features may not be atmospheric.","marker":"(55)"}],"fun_headline_variants":["JWST data show hot rocky exoplanets as bare rocks","No atmospheres detected on JWST's rocky exoplanets","JWST rules out thick CO2 skies on hot rocky worlds","JWST finds no air on rocky exoplanets yet"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The argument depends on treating the seven published eclipse measurements as equally reliable; if the instrument noise that affected one of them, or the multiple possible interpretations of two others, are underestimated, the average temperature that rules out thick atmospheres could move.","fun_headline_variants_meta":{"raw":{"variants":["JWST data show hot rocky exoplanets as bare rocks","No atmospheres detected on JWST's rocky exoplanets","JWST rules out thick CO2 skies on hot rocky worlds","JWST finds no air on rocky exoplanets yet"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000698,"raw_usage":{"total_tokens":3264,"prompt_tokens":1168,"completion_tokens":2096,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":784,"completion_tokens_details":{"reasoning_tokens":2026}},"tokens_in":784,"tokens_out":2096,"duration_ms":18278,"temperature":1.0,"reasoning_tokens":2026,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-06T21:01:14.182049+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"A JWST/MIRI eclipse observation of a hot rocky planet showing a 15-µm brightness temperature well below the $0.95 \\pm 0.01$ bare-rock ensemble average together with a hotter 12.8-µm point would indicate a thick CO$_2$ atmosphere with a thermal inversion, falsifying the paper's no-thick-atmosphere conclusion. The joint 15-µm phase curve of TRAPPIST-1b and c described in the paper would also falsify the bare-rock picture for at least one planet if it detects substantial day-night heat redistribution.","supporting_citations":[],"review_version":1}