Meteorite Petrophysics - A Useful Tool to Classify Meteorites and to Estimate the Physical State of the Parent Bodies

Meteorites are unique materials of our solar system since they provide direct information of the structure, type and evolution of their parent bodies. We have compiled a versatile data base which contains physical properties of more than 500 meteorites from Finnish, Swedish, Czech and Estonian collections. Included in the data base are also information of the state of weathering, the degree of shock, the FeNi-content, whether a sample is a fall or a find, and the various age data available from meteorites. The most useful petrophysical property is the natural remanent magnetization (NRM) since it provides a way to estimate the paleomagnetic field of its parent body. Magnetic susceptibility and density data provide a rapid way to classify meteorites. Magnetic hysteresis data, together with the NRM demagnetization characteristics and the anisotropy of susceptibility, provide further light into the thermal and shock histories of the meteorites. The data base can be used to (i) classify meteorites rapidly and without damage: e.g., to identify the chondrite classes E, H, L, LL, to identify an SNC or lunar meteorite, to identify the petrographic type LL3 to LL6, etc., (ii) model the global magnetic fields of the meteorite parent bodies (e.g., Vesta, Eros, Mars), or the anomalies to be encountered during the future orbits or landings on planets (Mercury, Mars) or on their moons (e.g., Phobos), (iii) provide a clue to the physical structure of the meteorite parent body (rubble pile or onion shape), (iv) study of the effects of shock and weathering on the physical properties of meteorites and their parent bodies, and finally (v) constrain the measurement ranges and sensitivities that the space probes (magnetometers, robot sensors) of the future satellite or landing missions must meet. We will discuss of the use of the meteorite petrophysical data base and present some examples of the applications of the data base in meteoritics and in planetary geophysics.