Nature of the far-tail signature during BepiColombo’s first Venus flyby

Ascertain whether the magnetic-field signature change observed by BepiColombo during its first Venus flyby in the far magnetotail (with an indicated interval spanning roughly 82–109 R_V downstream) corresponds to a bow shock/bow wave boundary crossing or is solely a manifestation of upstream solar wind variability.

Background

During BepiColombo’s first Venus flyby, identifying the outbound far-tail induced magnetospheric boundary and bow shock was challenging due to gradual transitions and the absence of clear plasma measurements. The authors mark a broad uncertainty interval for the potential crossings and discuss that the observed changes might reflect either a true spatial boundary crossing or temporal solar wind variations.

Because of this ambiguity, the specific physical nature of the magnetic signature in that interval remains unresolved and is explicitly identified as an open question by the authors.