Lunar X-ray fluorescence observations by the Chandrayaan-1 X-ray Spectrometer (C1XS): Results from the nearside southern highlands

S. Narendranath, P. S. Athiray, P. Sreekumar, B. J. Kellett, L. Alha, C. J. Howe, K. H. Joy, M. Grande, J. Huovelin, I. A. Crawford, U. Unnikrishnan, S. Lalita, S. Subramaniam, S. Z. Weider, L. R. Nittler, O. Gasnault, D. Rothery, V. A. Fernandes, N. Bhandari, J. N. GoswamiM. A. Wieczorek

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


The Chandrayaan-1 X-ray Spectrometer (C1XS) flown on-board the first Indian lunar mission Chandrayaan-1, measured X-ray fluorescence spectra during several episodes of solar flares during its operational period of ∼9. months. The accompanying X-ray Solar Monitor (XSM) provided simultaneous spectra of solar X-rays incident on the Moon which are essential to derive elemental chemistry. In this paper, we present the surface abundances of Mg, Al, Si, Ca and Fe, derived from C1XS data for a highland region on the southern nearside of the Moon. Analysis techniques are described in detail including absolute X-ray line flux derivation and conversion into elemental abundance. The results are consistent with a composition rich in plagioclase with a slight mafic mineral enhancement and a Ca/Al ratio that is significantly lower than measured in lunar returned samples. We suggest various possible scenarios to explain the deviations.

Original languageEnglish (US)
Pages (from-to)53-66
Number of pages14
Issue number1
StatePublished - Jul 2011

Bibliographical note

Funding Information:
We thank Vaishali Sharan and D.A. Daniel at ISRO Satellite Centre for programming support and Jason Gow at OU for useful comments. IAC and KHJ thank the Leverhulme Trust for financial support. We would also like to thank R. Korotev for discussion. OG participation to C1XS embarked on Chandrayaan-1 was supported by the Centre National dEtudes Spatiales (CNES). This is LPI contribution number 1615. We thank the anonymous referee and Dr.Lucy Lim (NASA/GSFC) for their useful comments which has greatly improved the manuscript.


  • Moon, Surface
  • Spectroscopy


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