Radioactive elements on Mercury's surface from MESSENGER: Implications for the planet's formation and evolution

Patrick N. Peplowski, Larry G. Evans, Steven A. Hauck, Timothy J. McCoy, William V. Boynton, Jeffery J. Gillis-Davis, Denton S. Ebel, John O. Goldsten, David K. Hamara, David J. Lawrence, Ralph L. McNutt, Larry R. Nittler, Sean C. Solomon, Edgar A. Rhodes, Ann L. Sprague, Richard D. Starr, Karen R. Stockstill-Cahill

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Abstract

The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.

Original languageEnglish (US)
Pages (from-to)1850-1852
Number of pages3
JournalScience
Volume333
Issue number6051
DOIs
StatePublished - Sep 30 2011

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Peplowski, P. N., Evans, L. G., Hauck, S. A., McCoy, T. J., Boynton, W. V., Gillis-Davis, J. J., Ebel, D. S., Goldsten, J. O., Hamara, D. K., Lawrence, D. J., McNutt, R. L., Nittler, L. R., Solomon, S. C., Rhodes, E. A., Sprague, A. L., Starr, R. D., & Stockstill-Cahill, K. R. (2011). Radioactive elements on Mercury's surface from MESSENGER: Implications for the planet's formation and evolution. Science, 333(6051), 1850-1852. https://doi.org/10.1126/science.1211576