BepiColombo, ESA's fifth cornerstone mission, is a planetary exploration mission to Mercury. On board of
BepiColombo's Mercury Planetary Orbiter (MPO), the MIXS instrument will perform a complete X-ray fluorescence
analysis of Mercury's crust with unprecedented spectral and spatial resolution. This is achieved by
using a lightweight X-ray mirror system and by using of DEPFET based Macropixel devices as X-ray detectors.
DEPFET based Macropixel detectors combine the advantages of the DEPFETs, like flexible readout modes,
Fano-limited energy resolution and low power consumption, with the properties of the drift detectors, like arbitrary
scalable pixel size and geometry. In addition, the excellent properties of the entrance window, like good
QE even in the low energy range and 100% fill factor, are preserved. An energy resolution better than 200 eV
FWHM @ 1 keV and an energy range from 0.5 keV to 10 keV, for a pixel size of 300 x 300 square micron, is
required. To be sensitive to the Iron-L energy, the quantum efficiency at 0.5 keV is required to be larger than
80%. Main challenges for the instrument are the difficult radiation and thermal environment in the mercury
orbit. The production of the first batch of flight devices has been finished at the MPI semiconductor laboratory,
and first laboratory modules have been built. The properties of the sensors have been evaluated at the BESSY
facility, and the devices have been used for XRF measurements at the ELETTRA synchrotron facility in Trieste.
The results of the first tests will be presented here.