X-ray Spectrometer
Outline of Instrument

Scientific Objectives

The XRS will globally determine major elemental composition (Mg, Al, Si, Ca, Ti, Fe, etc.) of the lunar crust with high spatial resolution.
The XRS will identify a rock type for each lunar geologic feature and survey its regional variation patterns.
=> to study the formation and evolution of lunar crust for understanding the lunar origin and evolution.

Specifications of XRS
  XRF-A
Lunar XRF Detector		 SOL-B
Solar X-ray Monitor		 SOL-C
XRF Calibrator
Detector CCD x 16 SiPIN Diode x 2 CCD x 1
Detection Area 100 cm2 Pinhole size 6 cm2
Field of View 12 x 12 deg 180 x 90 deg 180 x 90 deg
Footprint Resolution 20km (@ 100km) - -
Energy Range 0.7 -10KeV 1 -20KeV 0.7 -10KeV
Energy Resolution < 180eV
(@-50degC, Fe55)		 < 500eV
(@Fe55)		 < 160eV
(@-50degC, Fe55)
Operating Temperature < -40degC < 0degC < -40degC
ADC 12bit 8bit 12bit
Mission Packet EVENT, SPCTR
CHECK, IMAGE		 PIN-HIST, CAL EVENT, SPCTR
CHECK, IMAGE
XRS-E XRF-A SOL-BC XRF-A

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Principle of Observation

Solar X-ray induced Remote XRF spectrometry

Irradiation of solar X-rays excites atoms of the uppermost surface materials. Those excited atoms then transfer into ground state with emitting X-rays characteristic to each element. X-ray spectroscopy of sunlit surface thus provides information on elemental composition, along with concurrent monitoring of incident solar x-rays.


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Results Expected

Determine the elemental abundance and rock-type of the lunar crust

=>XRS will cover approximately 90% of lunar surface except for polar region and map elemental composition with spatial resolution of < 20km.
XRF-A (Lunar XRF Detector)
=>High energy resolution and large detection area with simultaneous driving of 16 CCDs.
SOL-B&C (Solar X-ray Monitor)
=>An elemental quantitative analysis using standard sample and solar x-rays concurrent monitoring.
Expected elemental distribution by XRS
and comparison with GRS
  XRS GRS
Mg/Si < 10km < 50km
Al/Si < 10km < 50km
Fe/Si delta (< 10km) < 30km
Mg# delta (< 10km) < 50km
Ti/Si delta (< 20km) < 50km
Ca/Si delta (< 20km) < 50km
K-Na-Ca   < 100km
Th, U, K
Volatile/Refractory		 N/A < 30km
< 30km

Result of component testSOL-B

SOL-C

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PI Introduction
XRS Manabu Kato

Manabu Kato

Department of Planetary Science,
JAXA/ISAS


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