10-Accretion of Mass 1,000 tons/day (300,000 metric tons/yr, Dubin and McCracken, 1962) to 55,000 tons/day (20,000,000 tons/yr, Fiocco and Colombo, 1964). However, a more recent estimate puts the accreting dust volume at approximately 78,000 tons/yr, or 214 tons/day.