The micrometeorite program at Dome C

We launched a program to recover cosmic dust (micrometeorites) from Dome C surface snow near the French-Italian station CONCORDIA. The Dome C snow is uniquely shielded from both morainic debris and aeolian dust within the micrometeorite size range (>= 25 mu m). The average temperature at Dome C ranges from -20 degrees C to -75 degrees C throughout the year. Once trapped in a cold and clean snow, the micrometeorites are expected to stay much better preserved from mechanical constraints and less altered by terrestrial Weathering than those of previous collections (mainly from Antarctic blue ice fields). We carried out 2 field expeditions in January 2000 and January 2002 using a new collection technique at Dome C. We successfully recovered micrometeorites from surface snow layers. By contrast with previous collections of micrometeorites, the particles from the CONCORDIA-Collection have suffered very little from terrestrial weathering. They have well constrained terrestrial ages. Their periods of fall overlap the ones of the particles found in the stratospheric interplanetary dust collections (IDPs) made by NASA. Because the precipitation rate is extremely low at Dome C, it is technically possible to exploit large areas (several tens of m(2) year) of annual snow layers formed up to 3 centuries ago, which allows searching for cometary particles from historical meteor showers.