The Ion Mass Analyzer (IMA) of the ASPERA-3 package flown on Mars Express provides ion measurements in the energy range 0.01 - 36 keV/q for the main ion components H+, H2+, He+, O+, and for the group of molecular ions with M/q ration between 20 and 80 amu/e. IMA has a 90 deg x 360 deg field
of view. Electrostatic sweeping performs elevation (+/- 45 deg) coverage.
The IMA sensor is a spherical electrostatic analyzer followed by a circular
magnetic separating section. A large diameter MCP with a discrete anode images
the matrix azimuth x mass.