Modeling of liquid water on CM meteorite parent bodies and implications for amino acid racemization

We have constructed an asteroid model with the intent of tracking the radia l and temporal dependence of temperature and composition throughout a 100-k m-diameter CM-type parent body, with emphasis on constraining the temperatu re and duration of a liquid water phase, We produce a nonuniform distributi on where liquid water persists longest and is hottest in the deepest zones and the regolith never sees conditions appropriate to aqueous alteration. W e apply the model predictions of the liquid water characteristics to the ev olution of amino acids. In some regions of the parent body, very little cha nge occurs in the amino acids, but for the majority of the asteroid, comple te racemization or even destruction occurs. We attempt to match our thermal model results with CM meteorite observations, but thus far, our model does not produce scenarios that are fully consistent with these observations. ( C) 2000 Academic Press.