The size and shape of the near-Earth asteroid belt

摘要: Abstract Evidence was recently reported for the existence of a near-Earth belt small, Earth-approaching asteroids (SEAs) with diameters less than ∼50 m. This result based upon observations made Spacewatch Telescope University Arizona during course an ongoing search asteroids. Using model to describe effects observational bias, it shown that orbits observed SEAs are inconsistent Earth approachers larger ∼1 km, and imply relatively high fraction Earth-like among SEAs. In this paper, new included bias is extended in order quantify number within further constrain their orbital distribution. The calculation shows relative approachers, deficient Aten-type which semimajor axis 1.0 AU. Instead, nearly all aphelia 1.4 AU (5 ± 3% total population) have perihelia between 0.9 1.1 AU, thus defining belt. Those > however, distribution indistinguishable from approachers. Taking into account does not significantly alter previously determined enhancement compared extrapolation numbers At ∼10 m, factor 40 2. Also, RMS impact velocity (17 km/sec) same as (18 km/sec).