Meteorites analysis techniques

Presolar grains are found in small quantities (with concentrations of ppb to several 100 ppm, see Table 2.1) in all types of primitive Solar System materials (Lodders Amari 2005 Zinner 2007). This includes primitive meteorites (the chondrites), IDPs, some of which might originate from comets, Antarctic micrometeorites (AMMs), and samples from comet Wild 2 collected by NASA s Stardust mission. Presolar grains are nanometer to micrometer in size. The isotopic compositions, chemistry, and mineralogy of individual grains with sizes >100 nm can be studied in the laboratory. Important analysis techniques are secondary ion mass spectrometry (SIMS) and resonance ionization mass spectrometry (RIMS)... 

Unlike stellar spectroscopy, the analysis of meteoritic grains and inclusions can provide an extremely precise isotopic breakdown. The weak point of this technique, however, is that the exact characteristics of the stars from which the grains formed can only be inferred. When we detect fight, we can deduce its celestial source by extending back its fine of incidence and we can determine the composition of the source from the spectral lines it contains. But we do not know where the meteorite grains came from, and only their composition can tell us anything of their origins. 

For the investigation of meteorites various experimental methods are applied, in particular mass spectrometry, neutron activation analysis, measurement of natural radioactivity by low-level coimting and track analysis. The tracks can be caused by heavy ions in cosmic radiation, by fission products from spontaneous or neutron-induced fission and by recoil due to a decay. Etching techniques and measurement of the tracks give information about the time during which the meteorites have been in interstellar space as individual particles (irradiation age). 

The principal focus of this review is on the analysis of the organic matter in the Murchison CM2 chondrite, together with data from other meteorites, where it can be shown that they have not been compromised by terrestrial contamination. It primarily covers work undertaken since 1980, a period that has seen the increasing use of stable-isotopic techniques to elucidate the sources of meteoritic organic matter, improved methods to study the structure of organic matter such as NMR, and the first in situ examinations of organic matter in meteorites these approaches have provided significant advances in our... 

A very interesting subject is the application of analytical pyrolysis for the study of biomarkers in extraterrestrial samples [2], Several meteorites and lunar samples were studied using this technique. Also, Viking Lander used a Py-GC/MS system to explore the Martian atmosphere and surface [74], Commonly, a stepped pyrolysis technique has been used in these studies to determine organic components in an inorganic matrix [75], The procedure involves a set of four or five temperatures that allow the analysis of trapped gases, analysis of small volatile molecules, and the performance of true pyrolysis on macromolecules. 

The analysis of the insoluble organic component (lOM) in carbonaceous chondrites is based on the techniques developed for coal, oil shales and petroleum source rocks. In order to analytically access the organic material the mineral phase of the meteorite is dissolved using a mixture of HCl and HF (9), leaving behind an organic residue that can be either processed further or used directly for analysis. 

Origin of solar system water Assessment of the degree of the isotopic variability of water on various solar system bodies is essential to understanding the origin of water in our solar system. Remote isotopic analysis of water (and other species) from more comets, as well as the analysis of returned, pristine cometary samples is required. Further analysis of meteorite samples with modern analytical techniques is also crucial. Specifically, H isotopic variability of water over micron scales in primitive meteorites must be confirmed by further analysis, because it is this observation that is driving the direction of models of water evolution in the solar system. 

Well over 10,000 papers dealing with activation analysis have appeared in the literature. Most of these (99%) have been published since 1955. Some of the more interesting applications have been determining potentially toxic trace elements in natural waters and environmental samples, authenticating paintings and other objects of art, and studying impurities in semiconductor materials, trace elements in plant and animal metabolism, and trace-element abundances in terrestrial rocks, meteorites, and lunar samples. In the analyses of lunar samples, more than twice as many trace-element determinations have been reported by activation analysis than by any other technique. In fact, the activation-analysis determinations on these rare samples probably exceed those by all other techniques combined. 

Whether the ionization is positive or negative, TIMS requires careful sample preparation, often involving considerable chemical processing to separate and purify the element of interest. TIMS finds applications in geoscience, environmental analysis, cosmochemistry, biosciences, medicine, material science, and physics. Samples generally include soil, minerals, meteorites, and biological tissue. More information on the specifics of the TIMS technique and its applications is in the monograph by De Laeter (2001). 

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