We present X-ray fluorescence observations of the lunar surface, made by the Chandrayaan-1 X-ray Spectrometer during two solar flare events early in the mission (12th December 2008 and 10th January 2009). Modelling of the X-ray spectra with an abundance algorithm allows quantitative estimates of the MgO/SiO 2 and Al 2O 3/SiO 2 ratios to be made for the two regions, which are in mainly basaltic areas of the lunar nearside. One of these ground tracks includes the Apollo 14 landing site on the Fra Mauro Formation. Within the 1σ errors provided, the results are inside the range of basaltic samples from the Apollo and Luna collections. The Apollo 14 soil composition is in agreement with the results from the January flare at the 1σ uncertainty level. Discrepancies are observed between our results and compositions derived for the same areas by the Lunar Prospector gamma-ray spectrometer; some possible reasons for this are discussed.
Bibliographical noteFunding Information:
The authors thank an anonymous reviewer and Tom Prettyman for their helpful and thoughtful comments that have served to significantly improve this manuscript. C1XS was an ESA-provided instrument on India's Chandrayaan-1 spacecraft. We thank ESA and ISRO for this collaborative opportunity, and for support in mission planning, spacecraft operations and data processing and archiving. S.Z.W., K.H.J. and I.A.C. acknowledge STFC and the Leverhulme Trust for financial support. This is LPI contribution 1636.
- Gamma-ray spectroscopy
- Lunar X-ray spectroscopy
- Lunar chemistry
- Lunar crust
- Lunar regolith