Determining Iron Distribution in the Regolith of 433 Eros

We have produced maps of iron abundance in bulk and iron-bearing mineral (pyroxene and olivine) soil components by combining Apollo Gamma-ray (AGR) and Clementine spectral reflectance (CSR) with lunar soil data to produce a more detailed model of crustal iron distribution than the separate datasets would provide. CSR measurements are most directly correlated to pyroxene iron in lunar soils. We subtracted pyroxene-recalibrated CSR data from AGR bulk iron abundance measurements: the residual iron is clearly correlated with olivine abundance in lunar soils. This work has implications for determining iron distribution for 433 Eros, a Class S asteroid, during the upcoming NEAR mission. We have modeled X-ray and Gamma-ray spectral line ratios for the best meteorite class candidates and can clearly distinguish between them, on the basis of abundance ratios. We have considered the equivalent spectral reflectance measurements, from which mineral abundances would be derived, as well, summarized in the qualitative Meteorite Classification matrix below. With these measurements, we should be able to determine Eros' nearest meteorite analogue, and iron abundance in each component. \begin{tabular}{llll} Si/Fe, Mg/Fe for XGRS & Fe Band Depth, Position & Albedo & Meteorite Class Medium, MediumHigh & Medium, shorter & Medium & Ordinary Chondrite, Type H Medium, High & Medium, longer & Medium & Ordinary Chondrite, Type LL High, Medium & Strong, shorter & High & Achondrite-Eucrite High, High & Strong, longer & High & Achondrite-Diogenite Low, Low & Weak & Medium & Stony Iron-Mesosiderite Low, MediumLow & Weak & Medium & Stony Iron-Pallasite