![]() ![]() This was meant to avoid any human contamination from the establishment of the field station at Concordia, which began in earnest in 1996. The researchers began their work with deposits dated to years before 1995, and then they excavated deeper, earlier layers. Engrand and CNRS A Close-up of Cosmic Dust Julien Rojas, a doctoral student at the University of Paris–Saclay and lead author of the study, notes that snowfall at Dome C has “quite low accumulation rate, but it’s enough to shield and preserve the particles.” The resulting thinness of each year’s layer of snow, Rojas says, allowed the team to collect decades of annual micrometeorite deposits in one location without having to melt huge amounts of ice. Located 1,100 kilometers inland on the continent and rising more than three kilometers above sea level, Dome C is practically perfect for cosmic dust collecting. In three field seasons stretched across the past two decades, Duprat and his colleagues visited the French-Italian Concordia station at a region called Dome C in Antarctica to collect micrometeorites. “The South Pole is by far the best because you are surrounded by oceans-you are completely isolated from mainlands,” says Duprat, who is a co-author of the study. The enduring ice also gives researchers a way of marking the age of micrometeorites, denoted by annual snow layers that persist year after year.Īlthough both poles have potential for micrometeorite research, Jean Duprat, a cosmochemist at the University of Paris–Saclay, prefers the southern ice. ![]() ![]() Scant material from elsewhere on Earth reaches those remote regions, allowing the barely changing ice sheets to soak up space dust with minimal contamination. Polar regions, such as Greenland and Antarctica, that are covered with ice year-round are hot spots for micrometeorite research because of their geographical isolation and stasis. With clean sampling techniques and accurate ages for dust deposits, the researchers calculated around 5,200 metric tons of micrometeorites fall to Earth every year. Now, in a study recently published in Earth and Planetary Science Letters, a team measuring micrometeorite accumulation in the pristine snow of Antarctica has provided the best-yet estimate for incoming extraterrestrial debris. In the past, researchers have sought to gauge the amount of such micrometeorites that reach Earth over time, but parsing cosmic dust is difficult on a planet that constantly whirls dust of its own making. But most of the space stuff that falls to Earth is quite small, submillimeter in size. Sizable chunks of rock and metal are the most dramatic examples, appearing as brilliant shooting stars during their fiery passage through the upper atmosphere and occasionally reaching the ground to become meteorites. Extraterrestrial material has rained down on our planet throughout its multi-billion-year history-and the celestial shower continues each passing day. Earth’s surface is constantly sprinkled with space dust. ![]()
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