Every year our planet encounters dust from comets and asteroids. These interplanetary dust particles pass through our atmosphere and form shooting stars. Some of them reach the ground in the form of micrometeorites. An international program conducted for nearly 20 years by scientists from the CNRS, the University of Paris-Saclay and the National Museum of Natural History, with the support of the French Polar Institute, found that 5,200 tons of these micrometeorites reach the ground annually. The study will be available in the journal Earths and planetary science letters from 15 April.
Micrometeorites have always fallen on our planet. These interplanetary dust particles from comets or asteroids are particles from tens to hundreds of millimeters that have passed through the atmosphere and reached the Earth’s surface.
To collect and analyze these micrometeorites, six expeditions led by CNRS researcher Jean Duprat have taken place over the past two decades near the French-Italian station Concordia (Dome C), located 1,100 kilometers off the coast of Adélie Land , in the heart of Antarctica. Dome C is an ideal place to collect due to the low snow accumulation rate and the almost absence of land dust.
These expeditions have collected enough extraterrestrial particles (30 to 200 micrometers in size) to measure their annual flow, which corresponds to the mass that accumulates on Earth per square meter per year.
If these results are applied to the entire planet, the total annual flow of micrometeorites is 5,200 tons per year. This is the main source of extraterrestrial matter on our planet, far ahead of larger objects such as meteorites, whose flow is less than ten tons per year.
A comparison of micrometeorite flux with theoretical predictions confirms that most micrometeorites probably come from comets (80%) and the rest from asteroids.
This is valuable information for a better understanding of the role of these interplanetary dust particles in the water and carbon molecule supply on young Earth.
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