Numerical simulations have been used to support the hypothesis that the Earth-Moon system is the product of an ancient catastrophic Giant Impact event. The original simulations suggested that the Moon was made mostly from the impactor material with only minor contributions from the Earth. In contrast, isotopic studies have demonstrated that the Earth and Moon are remarkably similar in their isotopic compositions for many elements (e.g., O, Ti, Cr and W isotopic anomalies and Mg and Si stable isotopes). This similarity between the Earth and Moon is unique in our Solar System when compared to other planetary bodies (such as Mars, Vesta 4 and other asteroids represented by the various classes of meteorites). The inconsistency between numerical simulations and cosmochemical observations is called an isotopic crisis for the Giant Impact theory of the Moon. In this talk, I will review previous isotopic evidences for the Origin of the Moon and present new Fe and K isotopic data for lunar samples. I will also discuss possible solutions for this current crisis, and what we can do in the next a few years.
Origins Postdoctoral Fellow - Dept. of Earth & Planetary Sciences (Stein Jacobsen Group)