Meteorites are the archives of our solar system. Their physical and chemical properties reflect the environment in which they formed, and are invaluable clues to understand the early stages of our solar system's evolution. Among those physical properties, the magnetization of meteorites is literally a record of all the magnetic fields they have encountered since their formation. Paleomagnetism is the discipline that aims at decyphering this record. Through various experiments, we can trace back the intensity of the magnetic fields meteorites were exposed to. If you want an overview of some of the recent advances in the field of extraterrestrial paleomagnetism, check my recorded lecture at the Collège de France (in French).
Meteorites experienced different types of magnetic fields. Some recorded the magnetic field threading the sun's protoplanetary disk (the solar nebula), which is thought to have played a key role in the formation of the first planetary bodies. A first aspect of my research is to identify and analyze the record of such meteorites, to obtain reliable empirical constraints on the strength of the nebula field that may feed models of protoplanetary disk evolution. A second aspect of my research is to develop new experiments to help us better interpret this magnetic record.
Some planetesimals formed early enough in the history of the solar system to melt and differentiate, forming a metallic core overlaid by a silicate mantle. Such planetesimals may have generated magnetic fields by advection of their cores (dynamo effect), much like the Earth does today. A third aspect of my research is to identify and analyze meteorites that recorded the magnetic fields generated by their parent bodies. Characterizing the strength and longevity of such fields places important empirical constraints on the physical properties and thermal evolution of planetesimals.
Additional aspects of my research include the study of the microstructural properties of metal-rich meteorites, which can also provide empirical constraints on the cooling history and size of meteorite parent bodies, and the study of the magnetic history of Mars, in preparation of the future NASA-ESA sample return mission MSR (fingers crossed!).