The Mercury Imaging X-ray Spectrometer (MIXS) onboard ESA's mission BepiColombo to Mercury will measure X-rays emitted from the surface and the magnetosphere.
The instrument consists of 2 heads, one for high and one for low spatial resolution. BepiColombo was launched in October 2018 with an Ariane V rocket and will orbit Mercury from end of 2025 onwards.
MIXS is designed to perform X-ray fluorescence (XRF) analysis of the surface of Mercury. XRF is a well known technique used for remote sensing the atomic composition of airless, inner solar system bodies. MIXS will detect K and L shell fluorescence line emission in the top few microns of the surface in the 0.5-7.5 keV energy range. This covers the emission energy of a number of important elements, including Mg, Al, Si, S, Ca, Ti and Fe.
MIXS consists of two channels - the MIXS-C, a collimator providing efficient flux collection over a broad range of energies with a wide field of view for planetary mapping and the MIXS-T, an imaging telescope with a narrow field for high resolution measurements of the surface. Both optical channels are read out by radiation hard, cooled (-40 °C) DEPFET (DEpleted P-channel Field-Effect Transistor) Macropixel focal plane arrays (resolution 100 eV at 1 keV).
DEPFET Macropixel sensor was developed at MPG HLL and system development was a collaborative effort with Max Planck Institute for extraterrestrial Physics and Max Planck Institute for Solar System research.
DEPFET Macropixel characteristics :
MIXS DEPFET pixel layout
Assembled MIXS DEPFET sensor
Majewski, P.; et al.;”DEPFET macropixel detectors for MIXS: First electrical qualification measurements”; IEEE Transactions on Nuclear Science 57(4):2389 – 2396; Sep 2010 DOI: 10.1109/TNS.2010.2053557
Majewski, P.; et al.;”DEPFET Macropixel Detectors for MIXS: Integration and Qualification of the Flight Detectors”; IEEE Transactions on Nuclear Science 59(5):2479-2486, Oct 2010 DOI: 10.1109/TNS.2012.2211616