Development of an ultra-miniaturised XRD/XRF instrument for the in situ mineralogical and chemical analysis of planetary soils and rocks: implication for archaeometry

An ultra-miniaturised (mass 1.5 kg; volume ~22 × 6 × 12 cm3) instrument which combines X-ray diffraction and fluorescence has been developed for the mineralogical and chemical characterization of Martian soils/rocks and was included in the ExoMars-Pasteur payload. The simultaneous in situ acquisition of elemental and mineralogical information would significantly improve any robotic missions and may unravel doubtful points regarding the mantle composition, crustal evolution and resource potential. The instrument employs a fixed reflection geometry to fulfil the diffraction principle which can be applied to unprepared sample as well. The instrument basically consists of a radioisotope as source of X-rays and a CCD-based detection system. This is the first successful diffraction experiment using a radioisotope since the early tests in the 60s. For terrestrial application the radioisotope can be easily replaced with a cathodic tube. The reduced dimension as well as the possibility to perform non-destructive analysis makes it suitable for terrestrial applications, particularly in the archaeometry field. We are envisaging an X-ray tomographer to map the mineralogical and elemental composition of an artefact (i.e., painting, pottery) directly on the object without sample preparation. Nowadays, X-ray radiography or computer tomography are becoming standard techniques widely used and accepted by art historians, archaeologists, curators and conservators as these methods enable information about the manufacturing process and the condition of an object without touching the artefact or even taking original sample material.