Precipitation of micrometeorites in Antarctica | Polarjournal
The plateau of Dome C, also called Dome Concordia or Charlie, is a plain situated at 3,233 metres above sea level. No elevations, nunataks or other landmarks protrude from the ice. But in the snow and ice of the plateau there are numerous traces of extraterrestrial material, which is well preserved here. Image: Stephen Hudson – Own work, CC BY 2.5 Wikipedia

It has been shown several times that Antarctica attracts not only humans and penguins, but also meteorites. But not only in the past the projectiles from space had hit our planet and the white continent. Even today, extraterrestrial material is raining down on us. A research group has now been able to determine how much it actually is and where it comes from, using samples from the middle of Antarctica.

Around 15,000 tonnes of dust and micrometeorites hit the Earth’s atmosphere each year, the French and US teams say in their study. Of this, around 5,200 tonnes penetrate to the earth’s surface, while the rest evaporates. It is mainly grains between 10 and 1,000 micrometers in size that make up the bulk of the extraterrestrial material rain. This is particularly important because it is probably how water molecules and other material reached the Earth, especially in its early days.

The samples were taken from trenches several metres deep and transported to the station where they were melted and the particles filtered out. The station is located 1,100 kilometers from the coast. Trenches were dug up to 3 kilometres from the station to prevent contamination from the station. Image: Rojas et al. (2021) Earth Plan Scie Lett

The pieces were found near the French-Italian Concordia station on the Antarctic plateau of Dome C. Here, at over 3,200 metres and more than 1,100 kilometres from the coast, conditions are ideal for the preservation and discovery of such material, the researchers state. “Little snow accumulation and no terrestrial dust whatsoever make Dome C an ideal sampling area,” the team says. In several expeditions and over a period of twenty years, the researchers were able to excavate trenches near the station, from which they extracted the micrometer-sized particles. This involved gently melting the snow and collecting and analysing the particles with filters. The trenches all had to be more than two metres deep to ensure that no particles prior to 1995 (the year the station was built) would be analysed.

The pieces discovered by the researchers in the snow of Antarctica are all between 30 and 350 micrometers in size. To discover these micrometeorites, vast amounts of snow had to be melted and analyzed. The yield: almost 1,300 micrometeorites (right) and over 800 cosmic spheres (top left). Image: Rojas et al. (2021) Earth Plan Scie Lett

The filtering produced 1,280 micrometeorites and 808 cosmic spheres, all between 30 and 350 micrometers in size. Calculations based on density and mass show that per square meter of the earth’s surface about 3 micrograms of micrometeorites and 5.6 micrograms of cosmic spherules hit Earth every year. Extrapolated, this amounts to around 5,200 tonnes of material per year. A more detailed analysis and with the help of a specific model, the researchers were also able to determine where the material came from. “Our simulations indicate that most of the micrometeorites and cosmic spherules originate from comets of the Jupiter family, and only a small fraction from the asteroid belt,” the researchers explain in a news release. This finding and the results are particularly important for further research in the field of astro- and geophysics. For if one assumes that this cosmic dust stream has existed since the early days of the earth, one can assume that a substantial part of the water and various elements could be of extraterrestrial origin in this way. This shows once again that the secrets of the universe can also be discovered in the white expanses of Antarctica.

Dr Michael Wenger, PolarJournal

Link to the study: J. Rojas, J. Duprat, C. Engrand, E. Dartois, L. Delauche, M. Godard, M. Gounelle, J.D. Carrillo-Sánchez, P. Pokorný, J.M.C.. Plane, The micrometeorite flux at Dome C (Antarctica), monitoring the accretion of extraterrestrial dust on Earth, Earth and Planetary Science Letters, Volume 560, 2021,116794, ISSN 0012-821X, https://doi.org/10.1016/j.epsl.2021.116794.

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