Probing the nature of extraterrestrial dust reaching the Earth�s surface collected from the Maitri station, Antarctica

Abstract

Micrometeorites (MMs) are extraterrestrial dust particles, in the size range of tens of �m to mm, recovered from the Earth�s surface primarily from deep-sea sediments, Antarctica, and also from space. The present collection of MMs (>50��m) obtained by melting ~50�t of ice near the Maitri station, Antarctica, has allowed us to investigate the abundance and properties of the particles by an unbiased collection technique. The collection reveals a large quantity of extraterrestrial material in the ~80-140��m size range. Previous collections have shown an abundance of particles at diameter ~200��m, which is in contrast to our findings. This can either be explained by movement of material within the ice or a recent influx of smaller particles. The smaller particles (<80��m) typically undergo atmospheric entry heating, contrary to earlier observations, which have suggested that they reach the Earth�s surface unmelted. Chondrules and refractory inclusions are rare in the collected MMs indicating that their contribution is only a small percentage. The Maitri station collection does not have a well-constrained ice accumulation rate and terrestrial age. Nevertheless, based on matching the previous well-documented flux calculation of Antarctica, we suggest a slow ice accumulation rate of <1.0�g�cm-2�yr-1 near Maitri station.