Context. Following its launch in April 2023, JUICE is now in its cruise phase to Jupiter, where it is scheduled to arrive in July 2031. JUICE carries a radiation monitor, namely the RADiation hard Electron Monitor (RADEM) to measure protons, electrons, and ions, detecting particles coming mainly from the anti-Sunwards direction. On 13 May 2024, a large solar energetic particle (SEP) event took place in association with an eruption close to the western limb of the Sun, as seen from Earth. Providentially, at that time, JUICE was located very close to STEREO-A, separated by only 0.13 au in radial distance, 0.3° in latitude, and 1.6° in longitude.

Aims. Our main aims are to characterise the observations within the interplanetary (IP) context whereby SEPs propagated to near-Earth, JUICE, and STEREO-A observers, while performing a first comparison of energetic particle instruments on board JUICE and STEREO-A spacecraft.

Methods. We analysed the IP context using in situ measurements and studied the proton anisotropies measured by near-Earth spacecraft and STEREO-A. We focussed on an isotropic period during the decay phase of the SEP event to compute the proton energy spectrum. We fit the STEREO-A spectrum and compared it to the one measured by SOHO and JUICE.

Results. We find the proton spectral indices measured by JUICE, SOHO, and STEREO-A to be similar. The proton fluxes measured by RADEM are in agreement with those from STEREO-A, with a deviation of less than 25%.

Conclusions. The RADEM instrument aboard JUICE is a valuable tool for measuring SEP events in the heliosphere, providing an excellent opportunity to study and characterise the energetic particle environment in the solar wind between 0.65 and 5.2 au. The intercalibration factors between the fluxes measured by STEREO-A and JUICE at the effective energies of 6.9 MeV, 13.3 MeV, 21.6 MeV, and 31.2 MeV are 1.02, 1.23, 1.12, and 0.95, respectively. We note that these intercalibration factors are valid only until 2024 July 10, when the configuration of the RADEM instrument was changed.

Context. We studied energetic particle intensity profiles observed by Solar Orbiter during the time period from April 2020 to April 2023, associated with the passage of interplanetary (IP) shocks. For our study we considered 58 IP forward shocks and analysed the possible correlations between some IP shock parameters and the electron and proton responses to the passage of the IP shocks. We investigated which shock signatures are more likely related to the efficiency of the IP shocks with respect to particle acceleration.

Aims. We introduced a variable that characterises the contamination induced by protons in the electron channels of the Electron Proton Telescope (EPT) part of the Energetic Particle Detector (EPD) suite of instruments on board Solar Orbiter, which allowed us to identify the cases in which the intensity time profiles of electrons at energies ≤240 keV showed a real response at the passage of IP shocks. In the case of protons, we searched for the response in seven energy ranges from 52 keV to 15 MeV, and based on the shape of the proton response at low energies (∼100 keV), we divided the profiles into weak responses, peaks (regular or irregular), plateaus, and unclear responses. For the regular peak and plateau types we constructed an average time profile by applying superposed epoch analysis. For the response in electrons and protons, and for the different types of proton responses at different energies, we analysed the corresponding IP shock parameters, aiming to understand which ones are important to form a certain type of time profile or to achieve a certain energy. We also included a comparison between the proton intensity time profiles in the upstream region and, assuming the predictions of the diffusive shock acceleration (DSA) theory, identified the values of the mean free path in several cases.

Methods. We found that the IP shock efficiency in the energisation of both electrons and protons is strongly energy dependent. Cases of electron acceleration are rare. Only in about ∼8% of the events for energies ≤100 keV and in ∼2% for energies ≤250 keV did the electron intensities show an unambiguous response at the passage of IP shocks (with those accompanied by a response being mainly oblique or quasi-perpendicular). The shocks for which we identified a response in ∼100 keV proton intensity time profiles come to ∼83% of the IP shocks under study, and are parallel or quasi-parallel. The ability to accelerate protons to higher energies and to form a particular shape of the particle response to the IP shock passage mostly depends on the IP shock speed.

Results. Based on the analysis of time profiles and the occurrence of unambiguous electron acceleration at shocks, the acceleration mechanism behind the electron energisation is unlikely to be DSA, but shock drift acceleration (SDA) remains a candidate for the acceleration mechanism. Proton time profiles of the plateau type around the IP shock front can be achieved with an IP shock speed above 800 km s−1 and an ambient mean free path ≤0.015 au, reproducing the asymptotic steady-state ion distribution reached in the classical DSA solution.

BepiColombo, the joint ESA/JAXA mission to Mercury, was launched in October 2018 and is scheduled to arrive at Mercury in November 2026 after an 8-year cruise. Like other planetary missions, its scientific objectives focus mostly on the nominal, orbiting phase of the mission. However, due to the long duration of the cruise phase covering distances between 1.2 and 0.3 AU, the BepiColombo mission has been able to outstandingly contribute to characterise the solar wind and transient events encountered by the spacecraft, as well as planetary environments during the flybys of Earth, Venus, and Mercury, and contribute to the characterisation of the space radiation environment in the inner Solar System and its evolution with solar activity. In this paper, we provide an overview of the cruise observations of BepiColombo, highlighting the most relevant science cases, with the aim of demonstrating the importance of planetary missions to perform cruise observations, to contribute to a broader understanding of Space Weather in the Solar System, and in turn, increase the scientific return of the mission.

This article is an erratum for: 10.1051/0004-6361/202450945