Measurement of neutral atoms and ions in Mercuryʹs exosphere

The Mercury apparatus for ions and atoms (MAIA) is a linear time-of-flight mass spectrometer operating in two modes, a neutral mode and an ion mode, which are used alternatively. MAIA is designed to determine the composition of Mercuryʹs exosphere and possibly its crust. The mass resolution of MAIA is sufficient to resolve all elements up to mass 300 amu. In both optional modes the mass range extends from 1 to 100 amu, and, if required, it can be increased up to 300 amu by changing the data acquisition mode. Even isotopes could be resolved, however, the partial pressures at Mercury are most likely too low for identification.