Noble gases and how they are analyzed

Noble gases are most abundant in planetary atmospheres, although even there they are only minor components. They have been measured in the gas envelopes of Venus, Earth (of course), Mars, and Jupiter. We will consider their utility in understanding planetary differentiation and atmospheric evolution shortly, but first we will focus on their rather miniscule abundances in meteorites and other extraterrestrial materials. 

Because the chemistry of noble gases is virtually an oxymoron, what is it that makes them so useful in cosmochemistry (and geochemistry) Noble gas nuclides are produced by a variety of nuclear transformation processes. Although the quantity of newly produced nuclei is typically very small, the even smaller background abundances of noble gases allow these nuclear transformations to be detected, unlike the situation for more common elements. It is understandable, then, that noble gas cosmochemistry mostly deals with isotopes. When applied to measuring noble gas isotopes, mass spectrometry is also much more sensitive than for other elements. 

Some noble gas components are referred to as in situ, meaning that they were produced within a given meteorite sample by nuclear transmutations. These are the nuclear 

Three-isotope plot of xenon in the Qinghen chondrite, released at different temperatures and illustrating various isotopic components. Modified from Huss and Lewis (1995). 

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