Solar Orbiter in Venus' ionosphere: observations from the 4th flyby
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
Solar Orbiter entered the topside ionosphere of Venus for the first time when performing its 4th flyby of the planet, reaching an altitude of 378 km on 18 Feb 2025. High-cadence electron density measurements showed previously unresolved fine-structuring within plasma regions and boundaries, particularly at the ionopause. During the rapid flyby, a rare snapshot of the entire induced magnetosphere was captured during calm solar wind conditions around solar maximum. A well-structured and a relatively steady plasma environment was observed. Assuming an electron temperature of 0.5 eV, pressure balance was found across the ionopause, while at the same time quasi-periodic density and magnetic field variations suggest boundary oscillations. Near closest approach, non-force free magnetic flux ropes were observed. Small-scale perturbations in both magnetic field strength and density across them indicate them being dynamically evolving, rather than in a stationary state.
Date Issued
2026-05-01
Date Acceptance
2026-04-17
Citation
Journal of Geophysical Research (JGR): Space Physics, 2026, 131 (5)
ISSN
2169-9380
Publisher
American Geophysical Union
Journal / Book Title
Journal of Geophysical Research (JGR): Space Physics
Volume
131
Issue
5
Copyright Statement
Copyright © 2026. American Geophysical Union. This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Publication Status
Published
Article Number
e2025JA034813
Date Publish Online
2026-04-30