Chemical compositions at Mars landing sites subject to Mars Odyssey Gamma Ray Spectrometer constraints

Suniti Karunatillake, John M. Keller, Steven W. Squyres, William V. Boynton, Johannes Brückner, Daniel M. Janes, Olivier Gasnault, Horton E. Newsom

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The Mars Odyssey Gamma Ray Spectrometer (GRS) is the first instrument suite to return elemental abundances throughout the midlatitudes of Mars. Concentrations of Cl, Fe, H, K, Si, and Th have been determined to tens of centimeter depths as mass fractions with reasonable confidence. Comparing such data with, or normalizing them to, in situ compositional data is difficult due to issues such as dramatic differences in spatial resolution; difficulties in convolving densities, abundances, and compositions of different regolith components; and a limited number of elements observed in common. We address these concerns in the context of the GRS, using Si at Pathfinder to normalize remote data. In addition, we determine representative in situ compositions for Spirit (both with and without Columbia Hills rocks), Opportunity, and Viking 1 landing sites using GRS-derived H content to hydrate the soil component. Our estimate of the Si mass fraction at Pathfinder, with 13% areal fraction of rocks, is 21%. The composition of major elements, such as Si and Fe, is similar across the four landing sites, while minor elements show significant variability. Areal dominance of soil at all four landing sites causes representative compositions to be driven by the soil component, while proportionally large uncertainties of bulk densities dominate the net uncertainties. GRS compositional determinations compare favorably with the in situ estimates for Cl and K, and for Si by virtue of the normalization. However, the GRS-determined Fe content at each landing site is consistently higher than the in situ value.

Original languageEnglish (US)
Article numberE08S90
JournalJournal of Geophysical Research: Space Physics
Volume112
Issue number8
DOIs
StatePublished - Aug 20 2007

Fingerprint

Mars landing sites
Gamma ray spectrometers
gamma ray spectrometers
landing sites
Landing
mars
Mars
chemical composition
spectrometer
soils
Chemical analysis
Soils
Rocks
rocks
Columbia (Orbiter)
normalizing
regolith
soil
temperate regions
estimates

ASJC Scopus subject areas

  • Oceanography
  • Astronomy and Astrophysics
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Geophysics
  • Geochemistry and Petrology

Cite this

Chemical compositions at Mars landing sites subject to Mars Odyssey Gamma Ray Spectrometer constraints. / Karunatillake, Suniti; Keller, John M.; Squyres, Steven W.; Boynton, William V.; Brückner, Johannes; Janes, Daniel M.; Gasnault, Olivier; Newsom, Horton E.

In: Journal of Geophysical Research: Space Physics, Vol. 112, No. 8, E08S90, 20.08.2007.

Research output: Contribution to journalArticle

Karunatillake, Suniti ; Keller, John M. ; Squyres, Steven W. ; Boynton, William V. ; Brückner, Johannes ; Janes, Daniel M. ; Gasnault, Olivier ; Newsom, Horton E. / Chemical compositions at Mars landing sites subject to Mars Odyssey Gamma Ray Spectrometer constraints. In: Journal of Geophysical Research: Space Physics. 2007 ; Vol. 112, No. 8.
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