X-ray fluorescence measurements of the surface elemental composition of asteroid 433 Eros

Larry R. Nittler, Richard D. Starr, Lucy Lim, Timothy J. Mccoy, Thomas H. Burbine, Robert C. Reedy, Jacob I. Trombka, Paul C. Gorenstein, Steven W. Squyres, William V. Boynton, Timothy A.C. Mcclanahan, Jesse S. Bhangoo, Pamela E. Clark, Mary Ellen Murphy, Rosemary V. Killen

Research output: Contribution to journalArticle

90 Scopus citations

Abstract

We report major element ratios determined for the S-class asteroid 433 Eros using remote-sensing x-ray fluorescence spectroscopy with the near-Earth asteroid rendezvous Shoemaker x-ray spectrometer (XRS). Data analysis techniques and systematic errors are described in detail. Data acquired during five solar flares and during two extended "quiet Sun" periods are presented; these results sample a representative portion of the asteroid's surface. Although systematic uncertainties are potentially large, the most internally consistent and plausible interpretation of the data is that Eros has primitive Mg/Si, Al/Si, Ca/Si and Fe/Si ratios, closely similar to H or R chondrites. Global differentiation of the asteroid is ruled out. The S/Si ratio is much lower than that of chondrites, probably reflecting impact-induced volatilization and/or photo- or ion-induced sputtering of sulfur at the surface of the asteroid. An alternative explanation for the low S/Si ratio is that it reflects a limited degree of melting with loss of an FeS-rich partial melt. Size-sorting processes could lead to segregation of Fe-Ni metal from silicates within the regolith of Eros; this could indicate that the Fe/Si ratios determined by the x-ray spectrometer are not representative of the bulk Eros composition.

Original languageEnglish (US)
Pages (from-to)1673-1695
Number of pages23
JournalMeteoritics and Planetary Science
Volume36
Issue number12
DOIs
StatePublished - Dec 1 2001

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

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    Nittler, L. R., Starr, R. D., Lim, L., Mccoy, T. J., Burbine, T. H., Reedy, R. C., Trombka, J. I., Gorenstein, P. C., Squyres, S. W., Boynton, W. V., Mcclanahan, T. A. C., Bhangoo, J. S., Clark, P. E., Ellen Murphy, M., & Killen, R. V. (2001). X-ray fluorescence measurements of the surface elemental composition of asteroid 433 Eros. Meteoritics and Planetary Science, 36(12), 1673-1695. https://doi.org/10.1111/j.1945-5100.2001.tb01856.x