{"id":"3cb53e2e-01e5-4925-9734-efcb27d34d0d","arxiv_id":"1908.08362","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":4.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"Solar Cycle 25 is projected to remain weak, so HZE cosmic-ray fluxes should stay near elevated solar-minimum levels through at least 2031, increasing radiation risk for Mars missions.","lead":"Using 318 years of sunspot records plus a neural-network forecast, the authors project that Solar Cycle 25 will stay weak, keeping galactic cosmic-ray heavy-ion fluxes high and raising radiation risk for Mars missions. The paper connects this forecast to ACE spacecraft measurements of HZE particle fluxes and argues that the quiet period may extend into the 2030s.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The low-activity-until-2031/2042 claim rests on visual wavelet matching plus an appended HRNN forecast whose output is then re-analyzed; the post-2018 low-coefficient band may be an artifact of the forecast or of wavelet edge effects, and no significance test supports the recurrence pattern.","rationale":"The paper contains useful, real data description: ACE/CRIS HZE flux anti-correlation with SSN, FFT periodicities (11, 22, 53, and 107 years), and a credible warning about radiation risk if solar activity remains low. However, the extension to Cycle 25/26 is the hinge of the article's practical conclusion, and that hinge is a visual pattern match plus an appended external forecast. The reader's conditional verdict is appropriate; my concern strengthens the reason for conditionality but does not change the verdict, because the paper openly calls the extension a model prediction and the observed ACE data from Cycle 24 are genuine. The proposed sensitivity test and cone-of-influence overlay would either rescue the wavelet argument or demonstrate that the main prediction is not independently supported, which is exactly the quantitative support the paper currently lacks.","tokens_in":7836,"tokens_out":5151,"duration_ms":55297,"concrete_test":"Recompute Figure 6 after replacing the appended HRNN 2019–2031 SSN values with a null continuation—for example, the observed 2009–2018 SSN repeated, or a flat series at the 2018 value—and overlay the wavelet cone of influence. If the low-coefficient column through 2031 persists and lies outside the cone for all null continuations, the conclusion is robust to the forecast and edge effects; if it disappears or falls inside the cone, the \"continuation of low activity\" is an artifact of the appended forecast or boundary treatment, and the projection to 2031/2042 is unsupported.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper's central claim—elevated HZE/GCR fluxes through Cycle 25 and probably 26—depends on the assertion that the current low-activity epoch will mirror the ~1800 and ~1900 quiet epochs. The only support offered in Section 3 around Figure 6 is \"visual pattern recognition\" of continuous wavelet coefficients of the SSN series extended to 2031. Two mutually reinforcing problems undermine this. First, the extended series analyzed in Figure 6 includes the HRNN-predicted 2019–2031 SSN values as input; the low wavelet coefficients after 2018 are therefore in large part manufactured by the very forecast whose validity the wavelet analysis is taken to confirm. The wavelet transform cannot serve as independent evidence for the forecast. Second, the wavelet coefficients at the right edge of the 331-point series lie within the cone of influence and are sensitive to the chosen boundary treatment; the apparent \"continuation\" of low coefficients into 2031 may be an edge artifact rather than a property of the data. No significance test, surrogate-data comparison, or out-of-sample validation is provided for the claimed 2–3 cycle recurrence, and the one-year SSN-minimum-to-flux-maximum lag is asserted from visual inspection rather than quantified. If the HRNN forecast is wrong—several published Cycle 25 predictions differ from it—or if the current quiet spell is shorter than the earlier two, the radiation-hazard projection for 2031 and beyond fails.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper examines the space radiation environment for future manned Mars missions, focusing on HZE particle fluxes modulated by solar activity. Using FFT and continuous wavelet analysis of yearly mean sunspot numbers (1700–2018), the authors identify ~11-, 22-, 53-, and 107-year periodicities and claim that wavelet spectra show three quiet epochs centered near 1800, 1900, and 2000, each lasting 2–3 solar cycles. They train a Hybrid Regression Neural Network (HRNN, code by Okoh) on the sunspot series to forecast Cycle 25 (2019–2031), append these predictions to the observed series, and re-run the wavelet analysis. From visual inspection of the resulting wavelet map, they conclude that the current low-activity spell will continue through Cycle 25 and possibly Cycle 26, implying elevated GCR/HZE fluxes and high radiation doses for Mars missions in the coming decades. ACE/CRIS data for elements B through Ni are presented to show higher HZE fluxes during Cycle 24 than Cycle 23, attributed to persistently low sunspot numbers, with a claimed one-year lag between sunspot minimum and flux maximum.","tokens_in":8186,"tokens_out":2587,"duration_ms":28942,"significance":"If the central prediction—sustained low solar activity and elevated HZE fluxes through Cycle 25 and perhaps beyond—is correct, the implications for Mars mission design are substantial, as galactic cosmic-ray dose is a known hard-to-shield hazard. The paper brings together long sunspot records, spacecraft observations, and a forecast model in an accessible way, and the observational finding that HZE fluxes were higher in Cycle 24 than Cycle 23 is worth reporting. However, the main predictive claim is not currently supported by quantitative evidence: the wavelet-based recurrence argument rests on visual pattern recognition of a 331-year series without statistical significance testing, the extended-series wavelet map includes the HRNN forecast as input, and the claimed one-year lag is asserted rather than measured. Because these issues affect the core conclusion, the contribution as written falls short of a robust basis for mission-radiation projections, though the shortcomings are addressable with additional analysis rather than being fatal in principle.","major_comments":[{"comment":"The wavelet analysis of the extended series (Figure 6) uses the HRNN-predicted sunspot numbers for 2019–2031 as input to the same continuous wavelet transform that is then cited as evidence of continuing low activity. This is circular: the low wavelet coefficients after 2018 are in large part manufactured by the forecast whose validity the wavelet analysis is supposed to support. The manuscript even notes that 'this cannot be verified fully,' but it still presents the wavelet result as a confirmation. To support the claim, the authors should validate the HRNN forecast against actual observed Cycle 25 data (now available) or, at minimum, treat the forecast as a scenario rather than as independent evidence.","section":"§3, Figure 6"},{"comment":"The central assertion that 'the very low solar activity period is likely to continue not only up to 2031 but perhaps beyond during at least up to solar cycle 26' is based solely on 'visual pattern recognition' of wavelet coefficient contours. There is no statistical test (e.g., surrogate-data or Monte Carlo significance levels), no quantitative criterion for identifying a quiet epoch, and no comparison of the duration/amplitude of the three alleged quiet epochs with uncertainties. In addition, the post-2018 coefficients in Figure 6 lie at the right edge of the time series, within the cone of influence of the wavelet transform, where values are strongly affected by the boundary condition. The apparent continuation of low coefficients may therefore be an edge artifact. The authors should quantify the recurrence pattern, show robustness to boundary treatment, and provide significance estimates for the low-coefficient regions.","section":"§3, Figure 6"},{"comment":"The statement that 'there is a lag of at least one year between the SSN minimum and flux maximum' is asserted from visual inspection of the concurrent plot in Figure 3. This lag is load-bearing because the paper later projects high HZE doses up to 2032 by adding one year to the end of Cycle 25. The lag should be quantified, for example by cross-correlating monthly sunspot numbers with the CRIS flux series, and reported with confidence bounds. Without this, the timing of the projected radiation peak is unsupported.","section":"§3, Figure 3"},{"comment":"The claim that HZE fluxes in Cycle 24 are 'considerably higher' than in Cycle 23 is presented without any quantitative comparison or uncertainty measures. The plotted time series show an apparent enhancement, but there are no mean fluxes, error bars, or statistical tests for the difference between the two cycle-averaged periods. Given that this enhancement is one of the paper's key observational results and motivates the radiation-hazard concern, it should be quantified (e.g., cycle-averaged flux ratios with propagation of counting uncertainties).","section":"§3, Figures 2 and 3"}],"minor_comments":[{"comment":"The text states that GCR data were downloaded for 'the period 1977 to 2019,' but the ACE spacecraft was launched in 1997 and the figures show data beginning in 1997 or 2000. Please correct the reported coverage period.","section":"§2"},{"comment":"Figure 2 is described as showing flux values 'higher by more than one order of magnitude' for B and Fe compared with F and Sc; since the y-axis is logarithmic, this is plausible, but the statement would benefit from a numerical comparison in the text.","section":"§3"},{"comment":"The manuscript refers to approximate dose rates from the OLTARIS website but does not provide a citation for the specific quoted values; please add the appropriate reference or specify the run parameters used.","section":"§1 and §3"},{"comment":"The wavelet color scale is not defined quantitatively in the caption or text; specifying the coefficient normalization and color-bar units would help readers interpret 'low' and 'high' values.","section":"Figure 5"},{"comment":"Several typographical errors appear, for example 'the Sun is going through a very low 11-year activity phase under solar cycle 24' and 'the starting of cycle 25 may be delayed.' A careful proofreading pass would improve clarity.","section":"§3"},{"comment":"The reference list includes a mix of conference presentations, project reports, and journal articles; some entries cited in the text (e.g., 'Myung et al., 2007' and the OLTARIS dose rates) are not fully referenced, and the Hathaway citation has an incomplete author list.","section":"References"}],"recommendation":"major_revision","confidential_remarks":"This is a borderline case. The paper addresses an important applied problem and contains a useful observational data presentation, but the central predictive claim is supported by an argument that is circular and statistically unquantified. The main fixes—quantifying the lag, adding significance tests for the wavelet recurrence, and treating the HRNN forecast as a scenario rather than validation—are all feasible within the paper's scope, so I do not recommend rejection. However, if the authors decline to add these analyses, the conclusion about sustained low activity through 2031–2042 should be substantially softened. I would also note that the manuscript was submitted to Heliyon; this journal may want to verify that the paper meets its standards for statistical rigor."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Short version: this paper has one real observational contribution and one main speculative claim. The real contribution is the clear documentation, from ACE CRIS data, that HZE fluxes (B to Ni) ran higher across the whole of cycle 24 than during cycle 23, consistent with the weak sunspot cycle. The historical FFT and wavelet analysis of SSN (1700-2018) is standard and the identified periodicities (11, 22, 53, 107 years) are not controversial. The paper's main claim -- that low solar activity will persist through cycle 25 and likely cycle 26 (to ~2042), keeping GCR/HZE fluxes near maximum -- rests on a visual comparison of wavelet patterns around 1800, 1900, and 2000. That is not established.\n\nWhat the paper does well: it uses public data, shows the anti-correlation clearly, and is candid that the projection is a model prediction based on visual pattern recognition. The citations to the HZE and space radiation literature are appropriate. No invented data.\n\nThe soft spots are real and concentrated in the projection section (around Fig. 6). The wavelet analysis of the extended series is applied to the HRNN forecast's own output, so the continued low coefficients after 2018 are partly built into the input; the wavelet transform cannot be independent confirmation. The right edge of the transform is within the cone of influence, so the apparent continuation may be partly an edge artifact. There is no significance test for the ~100-year recurrence, no surrogate-data comparison, and no uncertainty on the HRNN forecast. The one-year lag between SSN minimum and HZE flux maximum is asserted from a visual inspection of Figure 3, not computed. If cycle 25 is stronger than the HRNN predicts -- several published forecasts disagree with it -- the multi-cycle hazard projection fails.\n\nProportionately: the qualitative message is plausible and the ACE flux enhancement is real. But the specific prediction of elevated HZE fluxes through 2031 and 2042 needs quantitative support. This paper is for readers who want a survey of the space-radiation context for Mars missions, not for anyone who needs a defensible forecast.\n\nRecommendation: it deserves peer review, not desk rejection, because the data are real and the question matters. A referee should require the authors to quantify the lag, provide uncertainties, and reframe the cycle-26 extension as a hypothesis. I would not cite its forecast in my own work.","headline":"Useful ACE HZE documentation and a plausible qualitative warning, but the multi-cycle low-activity projection rests on visual pattern matching and circular extension, so it needs quantitative support before it can be relied on.","tokens_in":8690,"tokens_out":2801,"would_cite":false,"duration_ms":28814,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"This paper argues that the Sun's current low-activity spell will persist through solar cycle 25, keeping galactic heavy-ion radiation near peak and elevating the risk for crewed Mars missions.","keywords":["galactic cosmic rays","HZE particles","space radiation","human Mars mission","solar cycle 25","sunspot numbers","wavelet analysis","solar activity prediction"],"falsifier":"Track the observed yearly-mean sunspot numbers through 2031 and the spacecraft-measured GCR/HZE fluxes over the same period. If the smoothed peak of solar cycle 25 climbs above roughly half the normal cycle peak (the amplitude of earlier quiet epochs) or if heavy-ion fluxes begin a sustained decline before the mid-2020s, the paper's prediction of a continuing quiet epoch and sustained high radiation levels is contradicted.","tokens_in":7625,"feed_emoji":"☢️","tokens_out":8882,"duration_ms":82110,"temperature":0.7,"pith_summary":"This paper argues that the Sun is in a century-scale quiet spell that began with solar cycle 24 and will likely extend through cycles 25 and perhaps 26, so the elevated galactic cosmic-ray and HZE (high-charge, high-energy) particle fluxes seen since about 2007 will persist through around 2031. The supporting analysis combines spacecraft measurements of heavy-ion fluxes with Fourier and wavelet transforms of more than 300 years of sunspot numbers, and a neural-network forecast of cycle 25. If correct, a crewed Mars mission in the next decade will face a radiation environment close to solar minimum for most of its duration, with heavy-ion fluxes that are hard to shield. Radiation dose is a major constraint on long-duration human missions, so this prediction directly affects mission design.","feed_headline":"Quiet Sun may persist through 2031, keeping Mars radiation high","feed_subtitle":"Wavelet patterns in 300 years of sunspot data suggest heavy-ion cosmic-ray fluxes stay elevated for astronauts.","key_machinery":"The load-bearing mechanism is the continuous wavelet transform of the yearly sunspot-number series, applied first to observed data (1700-2018) and then to the series extended to 2031 with a hybrid regression neural network forecast. The wavelet coefficient maps resolve the roughly 11-year Schwabe cycle, the 22-year Hale cycle, a 53-year cycle, and the roughly 107-year Gleissberg cycle in time, and they reveal vertical bands of low coefficients across all scales during the quiet epochs around 1800, 1900, and 2000. These quiet bands are what carry the prediction: cycle 24 sits in the third such band, and the forecast keeps it weak. A Fourier power spectrum identifies the dominant periodicities, and spacecraft measurements of heavy-ion fluxes link low sunspot numbers to elevated radiation levels.","core_discovery":"The central claim is that the very low solar activity of cycle 24 is not an isolated anomaly but part of a roughly century-spaced pattern, and that it will likely continue through cycle 25 (about 2019-2031) and possibly through cycle 26 (about 2031-2042), matching quiet epochs seen around 1800 and 1900. The wavelet transform of yearly sunspot numbers from 1700 to 2018 shows three quiet epochs; extending the series with the hybrid regression neural network forecast to 2031 preserves the quiet pattern. Because galactic cosmic-ray and HZE fluxes rise when sunspot numbers fall, with flux peaks lagging sunspot minima by about one year, the paper concludes that near-peak heavy-ion fluxes will persist until about 2032. The estimated enhancement is substantial: HZE fluxes inside a typical spacecraft in interplanetary space could be a factor of about three higher for low-sunspot cycles like 24.","pith_inferences":["If the century-scale pattern holds, cycle 26 (about 2031-2042) would also be weak, extending the high-radiation window beyond 2031 and altering any mission architecture that counts on a stronger solar maximum for shielding.","The quiet-epoch pattern could be tested statistically by comparing the durations and amplitudes of the three epochs and by checking whether the same epochs appear in other solar activity proxies, such as geomagnetic records or cosmogenic isotope data.","Coupling the predicted sunspot series to a modern radiation transport model would turn this solar-activity forecast into a concrete dose projection for specific Mars trajectories and surface stay times."],"forward_implications":["A crewed Mars mission launched in the 2020s will spend most of its transit in a solar-minimum-like radiation environment, with HZE fluxes near their peak through roughly 2032.","Cumulative astronaut doses will approach or exceed current career limits unless transit time is shortened or shielding is improved, since aluminum shielding of about 20 grams per square centimeter reduces the dose only slightly.","Because the heaviest fluxes lag sunspot minimum by about one year, launch and surface-schedule planning should be tied to the predicted cycle timing rather than to the nominal minimum year.","Robotic Mars missions with adequate shielding remain feasible, but the analysis implies that unshielded astronaut surface operations would need additional protective measures."],"supporting_citations":[{"why":"Describes the ACE spacecraft and its instruments, the source of the heavy-ion flux measurements used to show the cycle 24 enhancement.","marker":"Stone et al., 1998"},{"why":"Provides elemental composition and energy spectra of galactic cosmic rays during cycle 23, the reference data set for interpreting HZE flux levels.","marker":"George et al., 2009"},{"why":"Introduces the hybrid regression-neural-network method used to generate the sunspot-number forecast for cycle 25.","marker":"Okoh et al., 2018"},{"why":"Independent prediction of cycle 25 strength and timing that frames the low-activity scenario the paper compares against.","marker":"Bhowmik et al., 2018"},{"why":"Another cycle-25 prediction used as context for the expected amplitude of the next solar cycle.","marker":"Hathway et al., 2016"},{"why":"Supplies the galactic cosmic-ray model from which the factor-of-three flux enhancement for low-sunspot cycles is estimated.","marker":"Badhwar and O’Neill, 1992"},{"why":"Updates the Badhwar-O'Neill model with ACE energy spectra, supporting the GCR flux levels used in the radiation assessment.","marker":"O’Neill, 2006"},{"why":"Applies wavelet analysis to sunspot-group records, the methodological basis for identifying the Gleissberg-scale quiet epochs.","marker":"Frick et al., 1997"}],"fun_headline_variants":["Mars-bound astronauts face extended high radiation risk","Sun's quiet spell may last through 2031, spiking Mars radiation","Heavy-ion fluxes to stay high for Mars missions until 2032","Low sunspot cycle could keep HZE radiation high for Mars trips","Prolonged solar lull means more radiation for Mars crews"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The argument depends on the assumption that the visually identified pattern of quiet epochs repeating roughly every 100 years is real and will continue into the current era, and that the neural-network forecast of a weak cycle 25 is correct; if the quiet spell ends early or cycle 25 is stronger than predicted, the prediction of sustained high HZE fluxes through 2031 has no basis.","fun_headline_variants_meta":{"raw":{"variants":["Mars-bound astronauts face extended high radiation risk","Sun's quiet spell may last through 2031, spiking Mars radiation","Heavy-ion fluxes to stay high for Mars missions until 2032","Low sunspot cycle could keep HZE radiation high for Mars trips","Prolonged solar lull means more radiation for Mars crews"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000564,"raw_usage":{"total_tokens":2734,"prompt_tokens":1062,"completion_tokens":1672,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":678,"completion_tokens_details":{"reasoning_tokens":1583}},"tokens_in":678,"tokens_out":1672,"duration_ms":12906,"temperature":1.0,"reasoning_tokens":1583,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T11:42:21.637886+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Track the observed yearly-mean sunspot numbers through 2031 and the spacecraft-measured GCR/HZE fluxes over the same period. If the smoothed peak of solar cycle 25 climbs above roughly half the normal cycle peak (the amplitude of earlier quiet epochs) or if heavy-ion fluxes begin a sustained decline before the mid-2020s, the paper's prediction of a continuing quiet epoch and sustained high radiation levels is contradicted.","supporting_citations":[{"cited_title":"C., Frandsen, A","cited_arxiv_id":null,"evidence_quote":"Describes the ACE spacecraft and its instruments, the source of the heavy-ion flux measurements used to show the cycle 24 enhancement."},{"cited_title":"S., LaveK, A., Wiedenbeck, M","cited_arxiv_id":null,"evidence_quote":"Provides elemental composition and energy spectra of galactic cosmic rays during cycle 23, the reference data set for interpreting HZE flux levels."},{"cited_title":"I., Seemala, G","cited_arxiv_id":null,"evidence_quote":"Introduces the hybrid regression-neural-network method used to generate the sunspot-number forecast for cycle 25."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the galactic cosmic-ray model from which the factor-of-three flux enhancement for low-sunspot cycles is estimated."}],"review_version":1}