A document highlights an Li-based fluxing agent that enables sample fusion and quantitative Ar-release at relatively low temperatures (900–1,000 ºC), readily achievable with current flight resistance furnace designs. A solid, double spike containing known quantities of 39Ar and 41K was developed that, when added in known amounts to a sample, enables the extraction of a 4040K ratio for age estimation without a sample mass measurement.
The use of a combination of a flux and a double spike as a means of solving the mechanical hurdles to an in situ K-Ar geochronology measurement has never been proposed before. This methodology and instrument design would provide a capability for assessing the ages of rocks and minerals on the surfaces of planets and other rocky terrestrial bodies in the solar system.
This work was done by Joel A. Hurowitz, Michael H. Hecht, Wayne F. Zimmerman, Evan L. Neidholdt, Mahadeva P. Sinha, Wolfgang Sturhahn, Max Coleman, Daniel J. McCleese, Kenneth A. Farley, John M. Eiler, and George R. Rossman of Caltech, and Kathryn Waltenberg of the University of Queensland, Australia, for NASA’s Jet Propulsion Laboratory. NPO-48099
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In Situ Potassium-Argon Geochronology Using Fluxed Fusion and a Double Spike
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Overview
The document titled "In Situ Potassium-Argon Geochronology Using Fluxed Fusion and a Double Spike" outlines advancements in geochronology techniques developed by NASA's Jet Propulsion Laboratory (JPL) for analyzing planetary samples. The primary focus is on the in-situ measurement of ages of geological materials from planetary surfaces, particularly Mars, using potassium-argon (K-Ar) dating methods. This approach aims to enhance our understanding of the geological history and evolution of terrestrial bodies in the Solar System.
The document discusses the challenges of determining the absolute ages of planetary surfaces, which are often assessed through crater counting statistics. This method can be uncertain, especially for geologically active planets. The proposed in-situ geochronology capability seeks to provide more accurate age determinations, which are crucial for addressing fundamental scientific questions about planetary processes, such as climate change and geological events.
Key components of the geochronology system include the use of flux-assisted melting techniques to facilitate the release of argon isotopes from samples. The experimental setup involves a laser ablation system coupled with a mass spectrometer to analyze the isotopic ratios of argon and potassium. The document details the design of the flight system, including sample introduction mechanisms and the necessary instrumentation for effective analysis.
The results from laboratory experiments demonstrate the effectiveness of the proposed methods, showing good correspondence between known and measured elemental and isotopic ratios. The document emphasizes the importance of these techniques in selecting samples for return to Earth, ensuring that they capture significant periods in a planet's geological evolution.
Overall, the document highlights the potential of in-situ geochronology to revolutionize our understanding of planetary surfaces by providing precise age data. This capability could fundamentally change how scientists interpret the geological history of Mars and other celestial bodies, ultimately contributing to our broader understanding of the Solar System's evolution. The research is part of NASA's ongoing efforts to develop innovative technologies for planetary exploration and sample analysis.
