Curation and Storage of Astromaterials: A Magnetic Perspective

Abstract

In this exciting new era of sample return space missions and improved detection of meteorite falls, the curation of pristine astromaterials has become a central concern. Well-preserved meteorites and returned extraterrestrial samples are absolutely unique sources of information regarding the formation and evolution of our solar system. Among their numerous informative properties, the paleomagnetic records of meteorites and returned samples (i.e., their natural remanent magnetization, NRM) provide invaluable insight on the physical characteristics of the first planetesimals, the Moon and Mars and on the environment in which these objects formed, as well as they long term evolution. Unfortunately, the NRM of a rock is probably one of the easiest and fastest property to alter, and today, very little action is taken in most curation facilities and collections to avoid magnetic contamination. In particular, contact with magnets and other unidentified, yet omnipresent, sources of magnetic fields are responsible for erasing the 4.5-billion-year old paleomagnetic records of >60% of meteorites in collections. In this paper, we describe the principal sources of magnetic contamination that are found in curation or storage facilities and propose simple preventive solutions and monitoring strategies. We recommend that strict measures are taken at the very least for the most precious samples (i.e., returned samples, meteorite falls and rare meteorite finds). We also encourage curators to raise awareness among their regular providers regarding the unfortunate and widespread use of magnets for meteorite testing.