Instrumental Overview of an Active X-ray Spectrometer for Future Lunar Landing Mission

Abstract

An Active X-ray Spectrometer (AXS) is being developed as a rover-based elemental analyzing device for future lunar and planetary missions in order to obtain in situ geochemical analyses of rocks, regolith, and soil near landing sites. The AXS is composed of four active X-ray generators with pyroelectric crystals and a silicon drift detector (SDD). In this paper, the instrumental overview of AXS for future lunar and planetary landing/sample-return missions, and possible scientific targets of a lunar landing mission are presented and discussed.

Development of X-ray Generator for Active X-ray Fluorescence Spectroscopy of Future Lunar Landing Mission and Its Contribution to Lunar Science

“…According with our results, it is implied that the number of electron to the crystal increase by raising electric field formed between the Cu target and crystal. In our plan of AXS measurement, 9) two types of excitation sources with Mo and Cu metallic target are prepared in order to measure many element abundances from Na to Fe. Light elements such as Na, Mg, Al, Si, P are effectively measured by the Mo L X-ray (2.29 keV), while relatively heavy elements above P (to Fe) are measured by Cu K X-ray (8.04 keV).…”

“…Light elements such as Na, Mg, Al, Si, P are effectively measured by the Mo L X-ray (2.29 keV), while relatively heavy elements above P (to Fe) are measured by Cu K X-ray (8.04 keV). 9) The strong L X-ray emission of Ta (8.145 keV) with mostly same energy as Cu K X-ray (8.04 keV) in heating is very useful to excite the X-ray of relative heavy elements (e.g., Ca, Ti, Fe). Usage of the cylindrical target could be effective for the increase of X-ray emissions of PXG.…”

“…In future landing mission to the Moon, several putative landing sites which are interesting for lunar science, are expected, 9) : young mare areas, Th-rich regions, silicic volcanic deposits in the Procellarum KREEP Terrane (PKT), and South Pole-Aitken Terrane (SPAT). In PKT where the radioactive elements such as potassium, thorium, and uranium, [14][15][16] multiplicity of igneous activity occurred from basaltic to silicic volcanism.…”

“…AXG with a pyroelectric crystal, has been studied and under development toward the embarkation of AXS on the lunar and planetary landing rover. [6][7][8][9] Pyroelectric crystals such as LiTaO 3 are used for X-ray generator. 10) The pyroelectric X-ray generator (PXG) is suitable for space missions because of its small size, lightweight, and low-power consumption.…”