Every year, Earth encounters dust from asteroids and comets. These extraterrestrial dust particles move into our atmosphere and give rise to shooting stars. Some of them touch the ground in the form of micrometeorites. An international program for nearly 20 years managed by researchers from the National museum of natural history, CNRS, and the Université Paris-Saclay with the assistance of the French polar institute, has discovered that 5,200 tons per year of these micrometeorites reach the ground. The research will be available in the journal Earth & Planetary Science Letters on April 15.
Micrometeorites have continuously fallen on Earth. These extraterrestrial dust particles of a few tenths to hundredths of a millimeter from asteroids or comets are particles that have passed through the atmosphere and reached the Earth’s surface.
Over the last two decades, six teams led by CNRS scientist Jean Duprat have taken area to accumulate and examine these micrometeorites. This place is near the Franco-Italian Concordia station (Dome C), which is located 1,100 kilometers off the shore of Adélie Land, in the middle of Antarctica. Dome C is an excellent collection point due to the near absence of terrestrial dust and the low accumulation rate of snow.
These teams have collected enough extraterrestrial dust particles (varying from 30 to 200 micrometers in size) to estimate their annual flux, which matches the mass accreted on Earth per square meter per year.
If these outcomes are implemented to the whole planet, the entire annual flux of micrometeorites represents 5,200 tons per year. This is the prime cause of extraterrestrial dust on our planet, considerably ahead of bigger objects such as meteorites, for which the flux is less than ten tons per year.
A correlation of the flux of micrometeorites with analytical predictions authenticates that most micrometeorites plausibly come from comets (80%) and the rest from asteroids.
This data is essential to better explain the role played by these extraterrestrial dust particles in providing water and carbonaceous molecules on the young Earth.
- Comets are composed of ice and dust. They arrive from far distances, from the Kuiper belt to the external boundaries of the Solar System. As they move towards the Sun, comets become active through the sublimation of their ices and release cometary dust.
- An asteroid is a huge solid celestial body between a few hundred meters to several kilometers in size. The majority of these bodies are found in the asteroid belt between Jupiter and Mars.
- This program has got funding from the CNRS, IPEV, the Domaine d’intérêt majeur ACAV+, the CNES, the ANR, which supports study in the Ile-de-France territory in the disciplines of astrophysics and the conditions of the appearance of life, as well as from LabEx P2IO. The French Polar Institute (IPEV) and its Italian counterpart (PNRA) provided the logistical assistance required to take out the field collection program.
- The French laboratories involved are: the Laboratoire de physique des deux infinis — Irène Joliot-Curie (CNRS / Université Paris-Saclay / Université de Paris), the Institut de minéralogie, de physique des matériaux et de cosmochimie (CNRS / National museum of natural history / Université Sorbonne) and the Institut des sciences moléculaires d’Orsay (CNRS / Université Paris-Saclay). Three foreign laboratories are also involved: NASA’s Goddard Space Flight Center in the United States, the Catholic University of America, and the University of Leeds in the United Kingdom.
- 1 micrometer (µm) is equivalent to 0.001 millimeters, or one-thousandth of a millimeter.
J. Rojas, J. Duprat, C. Engrand, E. Dartois, J.D. Carrillo-Sánchez, P. Pokorný, L. Delauche, M. Godard, M. Gounelle, J.M.C. Plane. The micrometeorite flux at Dome C (Antarctica), monitoring the accretion of extraterrestrial dust on Earth. Earth and Planetary Science Letters, 2021; 560: 116794 DOI: 10.1016/j.epsl.2021.116794