The Near-Earth Asteroid Size–Frequency Distribution: A Snapshot of the Lunar Impactor Size–Frequency Distribution

Abstract It is shown that the size–frequency distribution (SFD) of a time-averaged projectile population derived from the lunar crater SFD of Neukum and Ivanov (in Hazards Due to Comets and Asteroids (T. Gehrels, Ed.), 1994, pp. 359–416, Univ. of Arizona Press, Tucson) provides a convincing fit to the SFD of the current near-Earth asteroid (NEA) population, as deduced from the results of asteroid search programs. Our results suggest that the shape of the SFD of the impactor flux has remained in a steady state since the late heavy bombardment, so that the current NEA population can be viewed as a snapshot of the flux of impactors on the Moon. The number of bodies in the projectile population with diameters of 1 km or more is 700±130, which is in good agreement with recent estimates of the total number of NEAs in this size range. Our results imply that the contribution to the projectile flux from comets is small for diameters below 10 km.

[1]  Kevin R. Housen,et al.  Some recent advances in the scaling of impact and explosion cratering , 1987 .

[2]  Mars/Moon Cratering Rate Ratio Estimates , 2001 .

[3]  G. Neukum,et al.  The Inner-Solar System Impact Record: Lunar, Terrestrial-Planet, and Asteroid Size-Frequency Data Comparison , 1994 .

[4]  S. Ostro,et al.  Recent radar observations of asteroid 1566 Icarus , 1999 .

[5]  A. Harris,et al.  Physical Characteristics of Near-Earth Asteroids from Thermal Infrared Spectrophotometry☆ , 1999 .

[6]  A. Harris,et al.  Thermal Infrared Spectrophotometry of the Near-Earth Asteroids 2100 Ra-Shalom and 1991 EE , 1998 .

[7]  H. J. Moore,et al.  Standard techniques for presentation and analysis of crater size-frequency data , 1978 .

[8]  G. Neukum,et al.  Size-frequency distributions of planetary impact craters and asteroids , 2001 .

[9]  R. Jedicke,et al.  The Orbital and Absolute Magnitude Distributions of Main Belt Asteroids , 1998 .

[10]  S. Croft.  Scaling of Complex Craters , 1985 .

[11]  G. Neukum,et al.  Impact Craters, NEA and Main Belt Asteroids: Size Frequency Distribution , 1999 .

[12]  G. W. Wetherill,et al.  Collisions in the asteroid belt , 1967 .

[13]  D. Jewitt,et al.  On the relative numbers of C types and S types among near-earth asteroids , 1989 .

[14]  S. Ostro,et al.  Radar Observations of Asteroid 2063 Bacchus , 1999 .

[15]  D. Rabinowitz,et al.  A reduced estimate of the number of kilometre-sized near-Earth asteroids , 2000, Nature.