Jackie A. Davies

The Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission is a NASA Small Explorer to determine the cross-scale processes that unify the solar corona and heliosphere. PUNCH has two science objectives: (1) understand how coronal structures become the ambient solar wind, and (2) understand the dynamic evolution of transient structures, such as coronal mass ejections, in the young solar wind. To address these objectives, PUNCH uses a constellation of four small spacecraft in Sun-synchronous low Earth orbit, to collect linearly polarized images of the K corona and young solar wind. The four spacecraft each carry one visible-light imager in a 1 + 3 configuration: a single Narrow Field Imager solar coronagraph captures images of the outer corona at all position angles, and at solar elongations from 1.5° (6 R _⊙ ) to 8° (32 R _⊙ ); and three separate Wide Field Imager heliospheric imagers together capture views of the entire inner solar system, at solar elongations from 3° (12 R _⊙ ) to 45° (180 R _⊙ ) from the Sun. PUNCH images include linear-polarization data, to enable inferring the three-dimensional structure of visible features without stereoscopy. The instruments are matched in wavelength passband, support overlapping instantaneous fields of view, and are operated synchronously, to act as a single “virtual instrument” with a 90 ^∘ wide field of view, centered on the Sun. PUNCH launched in March of 2025 and began science operations in June of 2025. PUNCH has an open data policy with no proprietary period, and PUNCH Science Team Meetings are open to all.

Observing and forecasting coronal mass ejections (CMEs) in real‐time is crucial due to the strong geomagnetic storms they can generate that can have a potentially damaging effect, for example, on satellites and electrical devices. With its near‐real‐time availability, Solar TErrestrial RElations Observatory‐heliospheric imagers (STEREO/HI) beacon data is the perfect candidate for early forecasting of CMEs. However, previous work concluded that CME arrival prediction based on beacon data could not achieve the same accuracy as with high‐resolution science data due to data gaps and lower quality. We present our novel machine‐learning pipeline entitled “Beacon2Science,” bridging the gap between beacon and science data to improve CME tracking. Through this pipeline, we first enhance the quality (signal‐to‐noise ratio and spatial resolution) of beacon data. We then increase the time resolution of enhanced beacon images through learned interpolation to match science data's 40‐min resolution. We maximize information coherence between consecutive frames with adapted model architecture and loss functions through the different steps. The improved beacon images are comparable to science data, showing better CME visibility than the original beacon data. Furthermore, we compare CMEs tracked in beacon, enhanced beacon, and science images. The tracks extracted from enhanced beacon data are closer to those from science images, with a mean average error of of elongation compared to with original beacon data. The work presented in this paper paves the way for its application to forthcoming missions such as Vigil and PUNCH.

Observing and forecasting Coronal Mass Ejections (CME) is crucial due to the potentially strong geomagnetic storms generated and their impact on satellites and electrical devices. With its near-real-time availability, STEREO-HI beacon data is the perfect candidate for efficient forecasting of CMEs. However, previous work concluded that prediction based on beacon data could not achieve the same accuracy as with high-resolution science data due to data gaps and lower quality. We have introduced a new method to improve the resolution and quality of near-real-time beacon data by using advanced machine-learning techniques while maintaining consistency between consecutive frames. This method also allows us to forecast intermediary and subsequent frames using a data-driven model for CME propagation within HI images. The output generated by our model produces smoother and more detailed time-elongation plots (J-plots) that are used as input for the Ellipse Evolution model based on Heliospheric Imager observations (ELEvoHl). We have compared the data produced by our model with the science data and analysed its impact on CME forecasting and propagation.

Timely and accurate prediction of coronal mass ejections (CMEs) is vital for mitigating the potential impact of severe space weather events on critical infrastructures. Currently, manual detection and tracking of CMEs as they traverse the heliosphere are the norm. This presentation introduces an innovative approach: the development and implementation of a machine learning algorithm for automatic detection and tracking of CMEs, leveraging data from various heliospheric imager (HI) instruments. The wealth of active spacecraft equipped with HI instruments provides a unique opportunity to train the algorithm using diverse datasets.This work gains significance in light of the upcoming launch of Vigil, a space weather monitor scheduled for deployment in the early 2030s at the L5 point. Vigil will continuously observe and provide real-time HI observations along the Sun-Earth line. Our presentation showcases preliminary outcomes from an automated CME detection and tracking algorithm, demonstrating its effectiveness with training on STEREO-HI data. We also discuss potential future steps and challenges in the development and testing of this algorithm, emphasizing its role in advancing operational space weather prediction capabilities, especially in anticipation of the Vigil mission.

The STEREO mission has paved the way for the forthcoming Vigil mission, set to launch around 2030. Based on the extensive data archives from STEREO's wide-angle cameras, the heliospheric imagers (HI), we aim to assess the suitability of these data for real-time space weather prediction.This study focuses on modeling the evolution of coronal mass ejections (CMEs) as they progress towards Earth, employing STEREO-A and STEREO-B observations from Vigil's future vantage point, the L5 point of the Sun-Earth system, with the drag-based ensemble model ELEvoHI.Our investigation aims to determine to what extent incorporating additional HI data (as it would be received in real-time) improves the forecasting accuracy and its impact on the prediction lead time.

Interaction mechanisms in the solar wind affect the evolution of magnetic structures, thereby mediating the properties acquired during their formation processes at the Sun as they propagate outward. Using remote-sensing and in situ observations across multiple spacecraft we investigate a magnetic-cloud-like structure (MCL) detected in situ on 3–4 July 2007 near the ecliptic plane at different longitudes with OMNI, STEREO-A and STEREO-B. The MCL is entrained in a corotating interaction region (CIR) originating in the northern heliospheric sector, creating a merged interaction region (MIR). Our multi-spacecraft analysis, facilitated by the small angular separation of 17° in longitude and the solar minimum background, reveals the “ageing” of the MCL–CIR interaction. Local negative expansion speeds of the MCL indicate compression increasing further downstream. Differences in size, the formation of the sheath, the presence of forward and reverse waves, and the small-scale structuring demonstrate the progression of the interaction. This unique opportunity to observe the temporal evolution of the MCL–CIR interaction highlights the intricate nature of solar wind structures and their interactions at 1 AU.

Using remote-sensing and in-situ observations across multiple spacecraft with complimentary methods of analysis, we investigate a Magnetic Cloud Like-structure (MCL) observed in-situ on 3–4 July 2007 near the ecliptic at OMNI, STEREO-A and -B (all within 15° longitude of Earth). The MCL is entrained in a Corotating Interaction Region (CIR) originating in the Northern heliospheric sector, to create a Merged Interaction Region (MIR). This event allows the comparison of MIR observations at different longitudes showing differences in size, formation of sheath, presence of forward and reverse waves and small-scale structuring, demonstrating the progression of the interaction between the CIR and MCL from West to East. In order to explore its origins further, we compare the MIR with the (Interplanetary) Coronal Mass Ejection (ICME/CME) studied in Maunder et al. (2022) in the mid-latitudes at Ulysses containing a Magnetic Cloud (MC) and present a comprehensive discussion of the challenges posed by observing and relating transients not in alignment, across different latitudes and longitudes, and in different solar wind environments. As the CME propagates almost directly towards Ulysses, we find through fitting and modelling that its flanks could also potentially skim the near-ecliptic spacecraft. Length-scale analysis appears to be consistent with this configuration. However, local expansion velocities of the MCL/MC indicate compression near the ecliptic and expansion at Ulysses and the magnetic flux rope orientations and helicities at the different latitudes oppose each other. The CIR likely causes more compression and re-aligns the transient axis orientation near the ecliptic while a High Speed Stream (HSS) from the Southern sector propagates directly into the back of the ICME/MC near the mid-latitude. Opposing signs of helicity could provide indications of flux added in the first stages of CME evolution or magnetic reconnection with the Heliospheric Current Sheet (HCS). These observations and analyses demonstrate the continued challenge of modelling and fitting the propagation of transients embedded in complex solar wind environments. We note some of the caveats and limitations in the methods and highlight the use of multi-spacecraft analysis to disentangle the origin and formation of ICME substructures from the solar wind and other transients.

Measuring magnetic fields in the inner corona, the interface between the solar chromosphere and outer corona, is of paramount importance if we aim to understand the energetic transformations taking place there, and because it is at the origin of processes that lead to coronal heating, solar wind acceleration, and of most of the phenomena relevant to space weather. However, these measurements are more difficult than mere imaging because polarimetry requires differential photometry. The coronal magnetograph mission (CMAG) has been designed to map the vector magnetic field, line-of-sight velocities, and plane-of-the-sky velocities of the inner corona with unprecedented spatial and temporal resolutions from space. This will be achieved through full vector spectropolarimetric observations using a coronal magnetograph as the sole instrument on board a spacecraft, combined with an external occulter installed on another spacecraft. The two spacecraft will maintain a formation flight distance of 430 m for coronagraphic observations, which requires a 2.5 m occulter disk radius. The mission will be preferentially located at the Lagrangian L5 point, offering a significant advantage for solar physics and space weather research. Existing ground-based instruments face limitations such as atmospheric turbulence, solar scattered light, and long integration times when performing coronal magnetic field measurements. CMAG overcomes these limitations by performing spectropolarimetric measurements from space with an external occulter and high-image stability maintained over time. It achieves the necessary sensitivity and offers a spatial resolution of 2.5″ and a temporal resolution of approximately one minute, in its nominal mode, covering the range from 1.02 solar radii to 2.5 radii. CMAG relies on proven European technologies and can be adapted to enhance any other solar mission, offering potential significant advancements in coronal physics and space weather modeling and monitoring.

Measuring magnetic fields in the inner corona, the interface between the solar chromosphere and outer corona, is of paramount importance if we aim at understanding the energetic transformations taking place there and which is at the origin of processes that lead to coronal heating, solar wind acceleration, and of most of the phenomena relevant to space weather. However, these measurements are more difficult than mere imaging because polarimetry requires differential photometry. The Coronal Magnetograph mission (CMAG) has been designed to map the vector magnetic field, line-of-sight velocities, and plane-of-the-sky velocities of the inner corona with unprecedented spatial and temporal resolutions from space. This will be achieved through full vector spectropolarimetric observations using a coronal magnetograph as the sole instrument on board a spacecraft, combined with an external occulter installed on another spacecraft. The two spacecraft will maintain a formation flight distance of 430 meters for coronagraphic observations, which requires a 2 m occulter disk radius. The mission will be preferentially located at the Lagrangian L5 point, offering a significant advantage for solar physics and space weather research. Existing ground-based instruments face limitations such as atmospheric turbulence, solar scattered light, and long integration times when performing coronal magnetic field measurements. CMAG overcomes these limitations by performing spectropolarimetric measurements from space with an external occulter and high-image stability maintained over time. It achieves the necessary sensitivity and offers a spatial resolution of 2.5 arcseconds and a temporal resolution of approximately one minute, in its nominal mode, covering the range from 1.02 solar radii to 2.5 radii. CMAG relies on proven European technologies and can be adapted to enhance any other solar mission, offering potential significant advancements in coronal physics and space weather modeling and monitoring.

Whitepaper #160 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: space weather applications; basic research. Additional topics: other space weather; inner heliosphere; solar physics; space-based missions/projects.