PHEBUS

The exosphere of Mercury has little magnesium and contains helium. Some details about its structure are currently being revealed by the PHEBUS instrument aboard the BepiColombo interplanetary mission — an ultraviolet spectrometer developed with IKI participation. PHEBUS observed Mercury during several flybys and is now preparing to operate in scientific orbit, which it is to entere at the end of 2026. Papers on these preliminary results were published in the Journal of Geophysical Research: Planets.