The small-comet hypothesis: An upper limit to the current impact rate on the moon

摘要: Frank et al. [1986b] and Sigwarth [1993] hypothesized the intense bombardment of terrestrial atmosphere by small comets. Their model requires that Moon is impacted comets (10 7 -10 8 g) at a rate almost one per minute. We calculate an object this mass, even with exceedingly low density relatively velocity, will nevertheless produce crater least 50 m in diameter. These craters excavate immature lunar soil very bright spot diameter 150 m. If low-density exist might not create deep [O'Keefe Ahrens, 1982], they disturb regolith sufficiently to detectable spots. small-comet hypothesis correct then near-global imaging returned Clementine 1994 should reveal 10 spots locations where are present images acquired 1960's early 1970's. find no new carefully-studied area 5.2x104 km 2 , so upper limit current cratering 33/yr, ∼10 4 below expected if were valid.