The extraterrestrial dust accretion rate on Earth at Dome C, Antarctica: a fresh look with 3He

• A new 3 bars pressurized filter system for ice and snow. • 3 He ET flux of (1.25±0.03) pcc STP.cm -² .ka -1 derived from 38 kg modern Concordia snow (Antarctica). • 3 He ET flux twice as precise as previous estimates from sediment and ice cores. • 65 % and 31 % of this 3 He ET flux carried by 5–25 µm and 25–62 µm cosmic dust, respectively. • New flux of (3.5 ± 0.5) kilotons·a ⁻¹ for extraterrestrial particles < 100 µm. Interplanetary dust particles (IDPs) and micrometeorites (MMs), from 1 µm to 5 mm, are the primary source of extraterrestrial (ET) material currently accreted on Earth. The flux of ET particles smaller than ∼50 µm is typically determined through optical counting, but it remains uncertain and may deviate from predictions made by numerical simulations. The volatile element content carried by this flux is still not well-constrained and is influenced by the potential effects of atmospheric heating. We developed a clean, pressurized system to extract cosmic dust from ∼38 kg of clean snow collected near the Concordia station (Dome C, Antarctica). We measured helium isotope concentrations in various granulometric fractions (> 62 µm, 25–62 µm, 5–25 µm and < 5 µm). The inferred global 3 He ET annual flux is (1.25±0.03) × 10⁻¹² ccSTP·cm⁻²·ka⁻¹ (weighted mean±1SD), consistent with previous 3 He ET flux estimates from marine sediments and polar samples. Our data shows that the majority of the 3 He ET flux (70 %) is carried by particles in the 5–25 µm size range, with 20 % attributed to the 25–62 µm fraction. Using an empirical relationship between 3 He ET concentrations and cosmic particle mass, we convert these fluxes into a global ET mass flux for particle diameters < 100 µm of (3.5±0.5) kilotons·a⁻¹ (weighted mean±1SD). This result is about 3 times higher than collection estimates from (Rojas et al., 2021) and aligns with CABMOD-ZoDy modeling, after atmospheric entry (Carrillo-Sánchez et al., 2020). This 3 He ET method is suited for detecting particles smaller than 100 µm, while collection results are more relevant for larger fractions.