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G. J. Consolmagno (Specola Vaticana), D. T. Britt (University of Central Florida)
Connecting a given meteorite type with a particular asteroid class is usually done by comparing the meteorite chemical and mineralogical composition to the spectral reflectance properties of the asteroid surface. While this has tremendously advanced our understanding of meteorites and led us to identify possible asteroidal parent bodies, it suffers from several difficulties.
As spectroscopists realize (but meteoriticists sometimes forget), the spectra of an asteroid characterizes only the top few microns of surface material. As meteoriticists realize (but spectroscopists sometimes forget), meteorites are often breccias and not always uniform in composition. (Furthermore, different meteorite classes can have similar chemical compositions but different physical properties, e.g., the presence or absence of chondrules. Detecting these differences remotely remains a challenge.)
Our current survey of the bulk and grain densities of many different meteorite classes, and collaborations (cf. Rochette et al. 2003, MAPS 38,251) surveying the magnetic susceptibility of meteorites, indicate that for the ordinary chondrites a combination of susceptibility and grain density data can unambiguously classify H, L, and LL meteorites. This classification is quick, accurate, and non-destructive. Most importantly, this classification is determined by the characteristics of the whole rock, not just a small piece on a thin section, thus accounting for inhomogeneities within the sample.
This classification technique (to be extended to other meteorite classes) allows the rapid characterization of returned samples from asteroid missions, without any contamination or loss of material. It also offers the prospect that future missions to asteroids can use measurements of asteroid density and interactions with the ambient solar magnetic field to characterize the material present throughout the asteroid, not merely the material on its surface.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.