Status Update on Strofio: Recovery and Performance Advancements Post-Launch Anomaly

The Strofio neutral mass spectrometer, part of the SERENA suite aboard BepiColombo, experienced a launch anomaly that left one of its electrodes (D5) permanently shorted to ground (0 V). Following an extensive diagnostic and testing campaign, we report major progress in recovering and even enhancing Strofio's operational capabilities despite this hardware limitation. In particular, molecular beam testing conducted in February 2025 led to the discovery of a new operational configuration that restores full mass range coverage (3–64 amu) with excellent mass resolution (m/Δm > 100 at mass 40). This configuration overcomes the constraints imposed by the D5 anomaly but requires alternating between two distinct modes to resolve the H and H₂ peaks (masses 1 and 2), mitigating spectral overlap effects inherent to Strofio’s rotating field time-of-flight technique. We present the updated operational parameters, validate the instrument’s performance under this new mode, and discuss the planned cross-calibration with other instruments in the SERENA suite to ensure data consistency. These advancements represent a significant restoration of Strofio's scientific capabilities and position the instrument to deliver high-quality compositional data during BepiColombo’s orbital mission at Mercury.