Accurate real-time and forecast of the space radiation environment caused by solar energetic particles (SEPs) is essential in supporting the human and robotic exploration activities in space. We implemented an automated and end-to-end pipeline based on the Solar Wind With Field Lines and Energetic Particles (SOFIE) model developed at the University of Michigan. SOFIE is a framework coupling several physics-based models that simulates the ambient solar wind, coronal mass ejections (CMEs), and SEPs. The ambient solar wind and the propagation of the CME is modeled using the Alfvén Wave Solar atmosphere Model–Realtime (AWSoM-R) model, a three-dimensional extended magnetohydrodynamic model that self-consistently accounts for Alfvén wave–driven heating and solar wind acceleration. The CME is generated by putting a Gibson–Low flux rope on the source region using the Eruptive Event Generator (EEGGL). The SEP acceleration and transport are modeled by the Multiple Field Line Particle Advection Model for Particle Acceleration (M-FLAMPA). We have implemented the SOFIE pipeline in which the ambient solar wind will be running continuously, ingesting hourly updated photospheric magnetic field observations to maintain an up-to-date solar wind solution in the heliosphere. When a CME is detected, the pipeline will launch a branched integrated CME and SEP simulation, in which the arrival of the Interplanetary Coronal Mass Ejection (ICME) and the complete SEP profiles at the energies of interest to the operation will be forecasted within a few hours of simulation time. The SOFIE pipeline is now fully automatic without human intervention. Model outputs and forecast products, including real-time solar wind conditions in the heliosphere, the forecasted arrival of the ICME and the proton fluxes will be made publicly available through the CLEAR website (https://solarwind.engin.umich.edu/). We will test the readiness and robustness of the pipeline and evaluate its performance during the Artemis-II mission.

We present a community effort to assess how open science can advance heliophysics and space weather modeling. Open science has the potential to enhance the quality and pace of scientific discovery, but its application to scientific modeling requires more careful consideration with respect to open data and open software guidelines, as complex scientific models are not ordinary software. We gathered feedback from modeling teams worldwide through a living survey and discussion sessions at the Open Science Workshop in College Park, USA, in 2024, and the COSPAR ISWAT Initiative Working Meeting in Cape Canaveral, USA, in 2025. We complement these findings with lessons learned from almost 25 years of experience at the Community Coordinated Modeling Center in enabling open use of models. We identify key roadblocks in current open science practices and guidelines and offer recommendations for future progress. Our findings are organized into four overlapping themes: open use of models and simulation results, open validation, open development, and open collaboration. An essential outcome of the discussion is the need for model developers and users to speak with a united voice and promote the role of models in future open science efforts. We introduce a new cross-domain community initiative called Heliophysics Open Modeling Environment (HOME), which will be integrated as an overarching activity within the COSPAR ISWAT Initiative. HOME will serve as a platform for modelers and model users to work together, facilitate community modeling, improve the scientific return on modeling investment, and advance innovation in heliophysics and space weather.

The recent deployment of two new neutron monitors, HLEA and THIMON, at the summit of Haleakalā, Hawaii, represents a significant advancement in the global neutron monitor network. Positioned at 3,052 meters above sea level, these monitors benefit from reduced atmospheric interference, providing high-quality measurements of galactic cosmic rays (GCRs) and solar neutrons. Operational since December 2024, HLEA and THIMON are filling a critical geographical gap in the Pacific Ocean region. Their strategic location offers unique opportunities to compare measurements with other neutron monitors, aiding in cross-calibration efforts and enhancing the reliability of the global network. We will cover the technical specifications of HLEA and THIMON, their initial performance metrics, and the first scientific results. We will also discuss their integration into the NMDB. As part of the broader scientific community’s efforts to maintain and expand neutron monitor capabilities, HLEA and THIMON underscore the importance of investing in new stations, maintaining robust data repositories, and fostering international collaboration.

The International Space Weather Action Teams (ISWAT) is a grass-roots initiative that emerged as a global force from a small group of original founders in just a few years. ISWAT, hosted by the COSPAR Panel on Space Weather (PSW), serves as a hub for self-organised topical collaborations addressing space weather challenges, from solar origins to impacts on Earth and other planets. ISWAT has an infrastructure of action teams grouped into clusters by spatial domains and physical phenomena, that encompass overarching activities, and facilitate teamwork without borders or barriers. Anyone in the community can create a team, or join an existing team by completing a simple online application form. ISWAT is a professional, high-expertise community that encourages the participation of early-career scientists and provides research, and high-level mentorship, and encourages team co-leadership by researchers at different career stages. The joint activities of ISWAT mutually benefit participants, supplement core independent capabilities and maximise return on international/national/regional agencies’ investments in space weather efforts.ISWAT was a driving force behind the COSPAR PSW-ISWAT Space Weather Roadmap. Many of the science papers for the Roadmap Special Issue 1 (Science and Applications) were led by the ISWAT Action Teams. The review papers for the COSPAR Special Issue 2 (Achievement and Future Goals, this issue) are aligned to mirror the ISWAT cluster structure. This paper narrates the history of ISWAT, describes its structure, core principles, and current status, and presents perspectives on ISWAT post-Roadmap activities while Bisi et al. (2026, this issue) provides the overarching outcomes of this Roadmap endeavor. The special focus of this manuscript is to lay out the plans for addressing Roadmap recommendations and to improve the cross-cluster working. Additional actions include establishing a new user-focused space weather training network, and exploring opportunities for collaborative shared environments and community modeling. First results are expected by the next ISWAT Working Meeting in spring 2027. ISWAT is aiming to provide a seedbed for a new generation of leaders and to serve as a resource for the International Space Weather Coordination Forum.

Abstract The CLEAR Space Weather Center of Excellence's solar energetic particle (SEP) model, SOlar wind with FIeld lines and Energetic particles (SOFIE), was run and evaluated on‐site during the Space Weather Prediction Testbed (SWPT) exercise at the National Oceanic and Atmospheric Administration's Space Weather Prediction Center (NOAA/SWPC) in May 2025. As a physics‐based SEP model, SOFIE simulates the acceleration and transport of energetic particles by the coronal mass ejection (CME)‐driven shock in the solar corona and inner heliosphere, and has been validated against historical events. However, questions remain regarding whether a physics‐based model, traditionally considered computationally expensive, could meet operational needs. The SWPT exercise offered a valuable opportunity to evaluate SOFIE under simulated operational conditions. On‐site interactive feedback from SWPC forecasters, Space Radiation Analysis Group (SRAG) console operators, Community Coordinated Modeling Center (CCMC) personnel, and Moon‐to‐Mars Space Weather Analysis Office (M2M SWAO) analysts led to significant strategic improvements in the model configuration. The simulation grid was optimized by combining a coarser background grid with higher‐resolution regions along the CME path and toward Earth, reducing computational cost without compromising accuracy. In this work, we present the simulated operational performance of SOFIE and its capability to predict SEP fluxes significantly faster than real time. During the SWPT exercise, SOFIE completed a 4‐day SEP simulation within 5 hr using 1,000 central processing unit cores, although the earliest SEP forecast was obtained a few hours after CME onset. This marks a milestone in demonstrating SOFIE's operational usefulness and robustness to support future human space exploration.

We present results over an 11-year Solar cycle of cosmic antiprotons based on 1.1×10^{6} events in the rigidity range from 1.00 to 41.9 GV. The p[over ¯] fluxes exhibit distinct properties. The magnitude of the p[over ¯] flux temporal variation is significantly smaller than those of p, e^{-}, and e^{+}. A hysteresis between the p[over ¯] fluxes and the p fluxes is observed, whereas the p[over ¯] and e^{-} fluxes show a linear correlation. With a model-independent analysis, we found a universal relation between the shape of the rigidity spectrum and the magnitude of flux temporal variation over an 11-year Solar cycle for both positively and negatively charged particles. The simultaneous results on p[over ¯] and p, e^{-}, and e^{+} provide unique information for understanding particle transport in the Solar System as a function of mass, charge, and spectral shape.

We report the properties of precision time structures of cosmic nuclei He, Li, Be, B, C, N, and O fluxes over an 11-year solar cycle from May 2011 to November 2022 in the rigidity range from 1.92 to 60.3 GV. The nuclei fluxes show similar but not identical time variations with amplitudes decreasing with increasing rigidity. In particular, below 3.64 GV the Li, Be, and B fluxes, and below 2.15 GV the C, N, and O fluxes, are significantly less affected by solar modulation than the He flux. We observe that these differences in solar modulation are linearly correlated with the differences in the spectral indices of the cosmic nuclei fluxes. This shows, in a model-independent way, that solar modulation of galactic cosmic nuclei depends on their spectral shape. In addition, solar modulation differences due to nuclei velocity dependence on the mass-to-charge ratio (A/Z) are not observed.

Solar Energetic Particle (SEP) events can adversely affect space and ground-based systems. Space weather effects associated with SEP events can impact communication and navigation systems, spacecraft electronics and operations, space power systems, crewed space missions, and commercial aircraft operations. With the increasing importance of accurate forecasting-particularly for upcoming human exploration missions such as Artemis-there is a clear need to transition SEP prediction models to operational readiness. Achieving this requires rigorous validation to ensure that the models perform reliably under real-world conditions and can support critical mission decision-making. In this work, we present the results of the validation of the different modules of the newly updated version of the ASPECS (Advanced Solar Particle Event Casting System) nowcasting (post-eruption) part of the tool based on the SEPVAL 2023 (SEP Model Validation) sample. Emphasis is given on the comparison of the different inputs/catalogs and the resulting performance of the tool. Metrics such as the Probability of Detection (POD), the False Alarm Rate (FAR), the Percent Correct (PC), the Heidke Skill Score (HSS), and the True Skill Score (TSS) are generated for each of the different ASPECS modules. Comparisons between the predicted and observed peak proton fluxes and SEP time profiles at E 10 MeV and E 100 MeV are discussed.

Context. Studying the transport of galactic cosmic rays (GCRs) is crucial for understanding the space radiation environment and large-scale heliospheric structures. Various numerical, observational, and theoretical studies have demonstrated that GCR fluxes are modulated by the interplanetary magnetic field (IMF), which evolves with the solar cycle. However, there are still open questions on how different modulation processes, and their dependence on the IMF, impact the GCR transport in the heliosphere. In particular, we still do not fully understand how GCR time variations lag behind solar activity changes, referred to as GCR delay time in this study. Aims. We aim to parameterize the GCR delay time with respect to several solar activity indices and determine how this delay changes with particle rigidity, thereby contributing to a better understanding of GCR modulation in the heliosphere. Methods. Based on long-term GCR observations with the SOlar and Heliospheric Observatory (SOHO) telescope, the Interplanetary Monitoring Platform-8 (IMP-8), and the Alpha Magnetic Spectrometer (AMS-02), we used the force-field approximation to derive an analytical formula for estimating the GCR modulation delay. We then applied information theory to quantify the GCR modulation delay innovatively and employed Monte Carlo methods to evaluate its uncertainty. Results. Consistent with previous findings, we confirm GCRs have a longer delay time for qA < 0 than qA > 0, where q is the GCR particle charge and A = 1 (or −1) if the solar magnetic field is predominantly outward (or inward) at the solar north pole. For protons with a rigidity of 0.8 GV or higher, the modulation delay time gradually decreases from 7–12 months to 2–3 months as rigidity increases and then remains constant, which can be explained by the finite propagation speed of solar activity information within the heliosphere. Conclusions. We formulate a rigidity-dependent expression for the GCR modulation delay using the force-field approximation and assess its applicability through observational analysis grounded in information theory. These findings offer new insights into the heliospheric transport of GCRs.

Bayesian inference methods such as Markov Chain Monte Carlo (MCMC) typically require repeated computations of the likelihood function, but in some scenarios this is infeasible and alternative methods are needed. Simulation-based inference (SBI) methods address this problem by using machine learning to amortize computations. In this work, we highlight a particular synergy between the SBI method of neural likelihood estimation and the classic MCMC method of Hamiltonian Monte Carlo. We show that approximating the likelihood function with a neural network model can provide three distinct advantages: (1) amortizing the computations for MCMC; (2) providing gradients for Hamiltonian Monte Carlo, and (3) smoothing over noisy simulations resulting from numerical instabilities. We provide practical guidelines for defining a prior, sampling a training set, and evaluating convergence. The method is demonstrated in an application modeling the heliospheric transport of galactic cosmic rays, where it enables efficient inference of latent parameters in the Parker equation.

Space radiation affects every aspect of spacecraft design and operation. As a part of the ISWAT (International Space Weather Actions Teams, http://iswat-cospar.org/) effort, this paper provides a comprehensive review of space radiation environment models that are commonly used by the spacecraft design community to estimate radiation effects on systems/components. The types of radiation effects discussed in this paper are total dose (both for ionizing and for non-ionizing), single event effects (SEE), surface and internal charging, and radiation effects at aviation altitudes. For each effect, a brief overview of the effect is described, relevant environment models are discussed, and the currently understood gaps and future needs are summarized. This paper serves as the radiation environment pathway-to-impact paper in the overall ISWAT Roadmap development.

Galactic cosmic rays (GCRs) are affected by solar modulation while they propagate through the heliosphere. The study of the time variation of GCR spectra observed at Earth can shed light on the underlying physical processes, specifically diffusion and particle drifts. We combine a state-of-the art 3D numerical model of GCR transport in the heliosphere with a neural-network-accelerated Markov chain Monte Carlo to constrain the rigidity and time dependence of the global transport coefficients, using precise GCR data from the PAMELA and AMS-02 experiments between 2006 and 2019.

We present the precision measurements of 11 years of daily cosmic electron fluxes in the rigidity interval from 1.00 to 41.9 GV based on 2.0×10^{8} electrons collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The electron fluxes exhibit variations on multiple timescales. Recurrent electron flux variations with periods of 27 days, 13.5 days, and 9 days are observed. We find that the electron fluxes show distinctly different time variations from the proton fluxes. Remarkably, a hysteresis between the electron flux and the proton flux is observed with a significance of greater than 6σ at rigidities below 8.5 GV. Furthermore, significant structures in the electron-proton hysteresis are observed corresponding to sharp structures in both fluxes. This continuous daily electron data provide unique input to the understanding of the charge sign dependence of cosmic rays over an 11-year solar cycle.

The particle and radiation environment in cis-lunar space is becoming increasingly important as more and more hardware and human assets occupy various orbits around the Earth and space exploration efforts turn to the Moon and beyond.Since 2020, the total number of satellites in orbit has approximately doubled, highlighting the growing dependence on space-based resources.Through NASA's upcoming Artemis missions, humans will spend more time in cis-lunar space than ever before supported by the expansive infrastructure required for extended missions to the Moon, including a surface habitat, a communications network, and the Lunar Gateway -a space station which will orbit the Moon.Cis-lunar space starts at the top of the Earth's atmosphere and extends out to the orbit of the Moon, including the ionosphere, magnetosphere, free space, and the lunar surface.This paper focuses on galactic cosmic rays (GCRs) and solar energetic particles (SEPs) that create a dynamic and varying radiation environment within these regions.GCRs are particles of hundreds of MeV/nucleon (MeV/n) and above generated in highly energetic astrophysical environments in the Milky Way Galaxy, such as supernovae and pulsars, and beyond.These particles impinge isotropically on the heliosphere and are filtered down to 1 AU, experiencing modulation in energy and intensity on multiple timescales, from hours to decades, due to the solar magnetic cycle and other transient phenomena.SEPs are particles with energies up to thousands of MeV/n that are accelerated in eruptive events on the Sun and flood the inner heliosphere causing sudden and drastic increases in the particle environment on timescales of minutes to days.This paper highlights a current and prospective future gap in energetic particle measurements in the hundreds of MeV/n.We recommend key observations near Earth to act as a baseline as well as distributed measurements in the heliosphere, magnetosphere, and lunar surface to improve the scientific understanding of these particle populations and sources.

A Forbush decrease (FD) is a sudden reduction of Galactic Cosmic Rays (GCRs) that is usually caused by intense solar wind transients, such as Interplanetary Coronal Mass Ejections (ICMEs) and Corotating Interaction Regions (CIRs). Using daily proton fluxes measured by AMS-02 between 2011 May and 2019 October, we identified 142 FD events with an automatic systematic analysis method. The properties of 47 FDs caused by ICMEs and of 54 FDs caused by CIRs were analyzed. We found that the rigidity dependence of the GCR flux decrease is generally better described by an exponential function for both ICME and CIR FDs. We also found that the FD Amplitude of ICME FDs has a moderate correlation with the minimum Dst index and a number of solar wind parameters, such as maximum temperature, pressure, and magnetic field. For CIR FD events, neither FD Amplitude nor Maximum Affected Rigidity had a significant correlation with solar wind parameters.

The Pacific Ocean region presents a significant gap in the equatorial coverage of the global Neutron Monitor (NM) network, hindering the detection of Solar Neutron Particles (SNP) and Galactic Cosmic Rays (GCR).To address this issue, we are redeploying the Haleakala Neutron Monitor (HLEA) on the island of Maui.HLEA was established in 1991 but was subsequently decommissioned in 2006 due to funding constraints.Its strategic location at a high altitude on Haleakala mountain, situated in the middle of the Pacific Ocean, offers unique advantages for SNP detection.The reinstatement of HLEA represents an invaluable opportunity to extend ground coverage for SNP and GCR detection, enhance the global NM network, and contribute to a deeper understanding of high-energy particle interactions.By harnessing the potential of this revitalized NM station, we aim to enrich space weather research and improve the efficacy of space weather monitoring systems, thereby enhancing our preparedness and resilience against space weather hazards.

Since the 1950s, neutron monitors (NMs) have successfully measured both the long-term and the short-term variation of Galactic Cosmic Rays (GCRs). NMs are also sensitive to solar energetic particles (SEPs) and solar neutron particles (SNPs), both detected as ground level enhancements. Since SNPs are not affected by the interplanetary magnetic field, they retain direct information about the nuclear reactions happening near the SEP acceleration site. The global NM network has still a huge gap over the equatorial Pacific for measuring high energy GCRs and SNPs which are best measured at low latitudes. We plan to extend the coverage of the world wide NM network for SNP and GCR observations by redeploying the Haleakala NM station (HLEA) on Maui, in time for the upcoming solar maximum (around 2025). Since NMs can only measure the total count rate, it is not trivial to derive the actual particle flux and to compare different station responses. We plan to calibrate the HLEA with the future AMS daily proton fluxes, extended until the ISS decommission date now planned in 2031, and to perform extensive Mote Carlo simulations of the detector and surrounding environment. The initial phase of the project has already started. Status of the upcoming HLEA NM detector is reported.

The Committee on Space Research (COSPAR) is updating its Roadmap on Space Weather. As input for this update, the COSPAR International Space Weather Action Teams (ISWAT) were asked to provide an overview of the current state-of-the-art and advancements since the last Roadmap (Schrijver et al., 2015), identifying gaps and opportunities for moving forward within the next 5 years — based on ongoing and planned missions, available modeling, and observational capabilities — and presenting an outlook beyond 5 years and recommendations on reaching long-term goals. While space weather is typically associated with short-term solar activity, knowledge of past solar variability observed and recorded through various parameters, including historical space weather events, informs us about the range of possible solar fluctuations. This long-term solar variability, belonging to the domain of space climate, is the prime focus of the ISWAT S1 Cluster. The goal of this paper is to describe the key objectives of the three S1 Action Teams, summarize the current state of knowledge of the topic that each team is focusing on, and identify the key science gaps that need to be addressed in each area.

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The particle and radiation environment in cis-lunar space is becoming increasingly important as more hardware and human assets occupy various orbits around the Earth and space exploration efforts turn to the Moon and beyond. Since 2020, the total number of satellites in orbit has approximately doubled, highlighting the growing dependence on space-based resources. Through NASA's upcoming Artemis missions, humans will spend more time in cis-lunar space than ever before supported by the expansive infrastructure required for extended missions to the Moon, including a surface habitat, a communications network, and the Lunar Gateway. This paper focuses on galactic cosmic rays (GCRs) and solar energetic particles (SEPs) that create a dynamic and varying radiation environment within these regions. GCRs are particles of hundreds of MeV/nucleon (MeV/n) and above generated in highly energetic astrophysical environments in the Milky Way Galaxy, such as supernovae and pulsars, and beyond. These particles impinge isotropically on the heliosphere and are filtered down to 1 AU, experiencing modulation in energy and intensity on multiple timescales, from hours to decades, due to the solar magnetic cycle and other transient phenomena. SEPs are particles with energies up to thousands of MeV/n that are accelerated in eruptive events on the Sun and flood the inner heliosphere causing sudden and drastic increases in the particle environment on timescales of minutes to days. This paper highlights a current and prospective future gap in energetic particle measurements in the hundreds of MeV/n. We recommend key observations near Earth to act as a baseline as well as distributed measurements in the heliosphere, magnetosphere, and lunar surface to improve the scientific understanding of these particle populations and sources.