Research Article

Assessing VB_z variations during CME propagation: a preparatory study for the HENON mission using EUHFORIA

¹ Department of Physics, University of Calabria, Ponte P. Bucci, Cubo 31C Rende Italy
² Heliospheric Physics Laboratory, Heliophysics Division, NASA Goddard Space Flight Center, Greenbelt MD 20771 USA
³ Goddard Planetary Heliophysics Institute, University of Maryland, Baltimore County Baltimore MD 21250 USA
⁴ Centre for Mathematical Plasma Astrophysics, Dept. of Mathematics, KU Leuven, Celestijnenlaan 200B 3001 Leuven Belgium
⁵ Institute of Physics, University of Maria Curie-Skłodowska, Pl. M. Curie-Skłodowska 5 20-031 Lublin Poland
⁶ National Institute for Astrophysics, Scientific Directorate, Viale del Parco Mellini 84 I-00136 Roma Italy
⁷ Space Dynamics Services S.R.L., Navacchio di Cascina, Pisa Italy
⁸ Institute of Space Astrophysics and Planetology – INAF, Via del Fosso del Cavaliere 100 00133 Roma Italy
⁹ Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Via G. Sansone 1 50019 Sesto Fiorentino Italy
¹⁰ INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5 I-50125 Firenze Italy
¹¹ INFN, Sezione di Firenze, Via G. Sansone 1 I-50019 Sesto Fiorentino (FI) Italy
¹² ARGOTEC S.R.L., San Mauro Torinese, Torino Italy
¹³ ESA-ESTEC, European Space Agency, Noordwijk Netherlands
¹⁴ Department of Physics and Astronomy, University of Delaware, Newark DE 19716 USA

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 21 October 2025
Accepted: 26 March 2026

Abstract

Coronal mass ejections (CMEs) are among the main drivers of space weather hazards. In this context, HENON is a new space mission designed to carry out observations in the solar wind upstream of the Earth, aiming to provide timely alerts for hazardous perturbations propagating towards the Earth. HENON will orbit Earth on a distant retrograde orbit, approximately 0.082 AU upstream of the Earth when it is on the Sun-Earth line. The measurements taken by HENON will allow us to determine plasma and magnetic field parameters with a lead time of several hours with respect to the Lagrangian point L1. We assess the V B _z parameter variations (the product of solar wind speed V and southward magnetic field B _z ) along the HENON orbit. Given its role as a primary driver of geomagnetic activity, we analyze how these measurements change with respect to Earth’s position to evaluate HENON’s forecasting potential. We used the FRi3D CME model of the EUHFORIA simulation code to characterize the initial properties of the CME. FRi3D allows us to set the CME magnetic field as a magnetic flux rope. From the simulation results, we evaluated the V B _z parameter at nine virtual spacecraft positions along the planned HENON orbit. The heliocentric longitudes of the virtual spacecraft range from about −6.9° to 6.9°, while the geocentric longitudes vary from −60° to +60° in steps of 15°. The initial direction of propagation of the CME central apex is either along the Sun-Earth line or at heliocentric longitudes of ±30°. We find that with the proposed orbital parameters, the values of the V B _z parameter along the HENON orbit is sufficiently similar to those measured in the vicinity of the Earth to be useful for space weather forecasts. At the same time, HENON permits to evaluate V B _z with a lead time of about 2−8 h, depending on the spacecraft position and the speed of the CME. The forecasting capabilities provided by HENON are expected to be foundational for the space weather community. This advancement has direct implications for enhancing the resilience of satellite communications and safeguarding critical infrastructure against space weather events.