This work reports on an attempt towards improving the Relativistic Electron Alert System for Exploration (REleASE): the occurrence of a type-III radio burst as a precondition for a REleASE forecast. REleASE forecasts are based on the detection of early arrival of near-relativistic electrons ahead of more hazardous protons from Solar Energetic Particle (SEP) events. The goal is to allow astronauts on a Lunar or Mars mission sufficient advance warning to reach a radiation shelter to minimize radiation dose exposure. We test a new system that sets a condition of the occurrence of a type-III radio burst, thus adding independent evidence of particle escape from the Sun, with the aim of reducing known sources of false-alarms of the existing REleASE system. The HESPERIA REleASE+ system, which takes advantage of availability of real-time solar radio observations during the passage of STEREO-A by Earth in 2023, has now been incorporated in the HESPERIA framework. We discuss the techniques used for automatic detection of type-III radio bursts preparing for its real-time implementation, the determination of selection criteria for type-III bursts that are candidates for solar proton events in the Earth-moon system, and first results of the combined system.

The Energetic Particle Detector (EPD) onboard Solar Orbiter is a suite of multiple sensors (Suprathermal Electrons Protons, STEP; Suprathermal Ion Spectrograph, SIS; Electron Proton Telescope, EPT; High Energy Telescope, HET), which measures particle intensities over a wide range of energies (from suprathermal to relativistic energies) and for different species (electron, protons, and heavy ions) in different directions. The EPD data center (http://espada.uah.es/epd) offers a primer venue to inspect the Solar Energetic Particle (SEP) activity, both to promptly check the most recent solar activity using quicklook plots based on low-latency data sets, and to perform deeper studies with data validated for scientific use. Among others, a series of plots and relevant information, such as the spacecraft maneuvers or sensor updates, are provided to the community. This facility gives access to all the data from the EPD sensors (which can be also found in the Solar Orbiter Archive), including Level 2 (calibrated) as well as more elaborated Level 3 data in the near future, which have further processing. An application programming interface (API) is also offered for accessing EPD data. Besides, during the first year and a half of observations, Solar Orbiter has completed three orbits, and EPD has measured several increases in particle fluxes, due to heliospheric and solar-origin events. Some of the events have been analysed and the flux enhancements have been tagged for future studies. This work aims to let the community know the availability of the instrument data products, and to explain how to properly use the provided data products and plots, as well as to summarise all the available studies published until now.

The Earth-Sun Lagrangian point 4 is a meta-stable location at 1 au from the Sun, 60° ahead of Earth’s orbit. It has an uninterrupted view of the solar photosphere from E30 to W150, centered on the Earth’s nominal magnetic field connection to the Sun. Such a mission on its own would serve as a solar remote sensing observatory that would oversee the entire solar radiation hemisphere (SRH) with significant relevance for human exploration of the Moon and Mars. In combination with appropriately planned observatories at L1 and L5, the three spacecraft would provide 300° longitude coverage of photospheric magnetic field structure, and allow continuous viewing of both solar poles, with >3.6° elevation. Ideally, the L4 and L5 missions would orbit the Sun with a 7.2° inclination out of the heliographic equator, 14.5° out of the ecliptic plane. We discuss the impact of extending solar magnetic field observations in both longitude and latitude to improve global solar wind modeling and, with the development of local helioseismology, the potential for long-term solar activity forecasting. Such a mission would provide a unique opportunity for interplanetary and interstellar dust science. It would significantly add to reliability of operational observations on fast coronal mass ejections directed at Earth and for human Mars explorers on their round-trip journey. The L4 mission concept is technically feasible, and is scientifically compelling.