Constraints on the composition of the earth's core can be obtained by comparing shock wave equation of state and compressional velocity at high pressure data to seismic data over the pressure and temperature range present in the earth's outer core. Knowledge of the composition of the core is inextricably interwoven with theories of the differentiation and thermal evolution of the earth. Recent results from this project constrain the temperature of a core in terms of the melting point of Fe and FeS. This award provides support for continuation of a program of exploration and measurements of the equation of state, pressure-volume-temperature relations of candidate core materials- Fe, FeS, and FeO. In addition to the equation of state longitudinal and bulk sound speed at high pressure and high temperatures using velocity interferometry and a new preheating technology will be measured. The regime of shock measurements of preheated samples is 1000 - 2500 K both in core materials and some minerals of mantle.
