Comparison of asteroid and meteorite spectra: Classification by principal component analysis

The relationships between asteroid and meteorite spectral types are a subject of much discussion and debate. To provide an overview of spectral similarities between and among asteroids and meteorites, the spectra of 103 meteorites and 411 asteroids were statistically compared using principal component analysis. This analysis produced a "map" of statistically defined spectral similarities in which distance is a measure of relative similarity. There appears to be considerably more spectral variance in the meteorite collection than is seen in the asteroids. Also, many planet-crossing asteroids are spectrally much more similar to the meteorites than most main belt asteroids. The principal components of meteorite spectra are, in general, offset from those of the bulk of the asteroid population. The offset of the carbonaceous chondrite and iron meteorites from their most frequently suggested asteroidal analogues is particularly notable. Finally, the analysis shows no direct meteorite analogues from the outerbelt B-, D-, F-, P-, and T-type asteroids, confirming that meteorites sample only a relatively limited portion of the inner asteroid belt.