Mercury, the innermost planet of the Solar System, hosts a tenuous and highly dynamic exosphere primarily composed of atoms released from its surface through processes such as solar wind sputtering, micrometeoroid impact vaporization, and thermal desorption. Understanding this exosphere provides key insights into surface–space environment interactions on airless bodies.
The ESA–JAXA BepiColombo mission, currently en route to Mercury, carries the PHEBUS (Probing of Hermean Exosphere By Ultraviolet Spectroscopy) instrument, designed to characterize Mercury’s exosphere in the ultraviolet range. During the mission’s cruise phase, PHEBUS has already acquired valuable observations during Mercury flybys, offering a unique opportunity to study exospheric composition and variability under different solar conditions.
In this seminar, I will present the first results from these flyby observations, discuss the detected species and their spatial distributions, and explore how these measurements contribute to our understanding of Mercury’s exosphere ahead of BepiColombo’s orbital phase.
