Hybrid powder / single-crystal X-ray diffraction instrument for planetary mineralogical analysis of unprepared samples

Grant #: NNX13AB05G
Senior Scientist: Philippe Sarrazin

We are developing a new type of X-ray diffraction (XRD) / X-ray fluorescence (XRF) planetary instrument based on a hybrid concept that allows performing both powder XRD and single crystal XRD.  The main benefit of this hybrid concept is the possibility to analyze minerals with limited or no sample preparation.

Powder XRD (pXRD), the technique used by the CheMin instrument of MSL, is used when fine-grained samples are presented to the instrument, either in their native state or after preparation with a grinding tool.

Single crystal XRD (sXRD) using polychromatic radiation (Laue diffraction) is applied when samples are too coarse to use pXRD.  The Laue analysis allows identification of minerals in unprepared samples and enable ab-initio determination of crystalline phases unknown to current crystallographic databases.

There is no change in the hardware configuration of the instrument from one technique to the other, the only difference being the way the data is processed and analyzed.  A possible implementation of the instrument concept is presented in Figure 1.

The concept will lead to a contact instrument fitted to the robotic arm of a rover, or fitted inside the rover/lander for analysis of delivered unprepared samples.