Recent compilations of the lunar impact record1,2, combined with the mass-scaling law for crater diameters in the large-body (gravity-scaling) regime3,4, allow an estimate of the total mass incident on the Moon during the period of heavy bombardment. By using only those craters and basins still extant, the calculation provides a lower limit which is independent of cometary flux models, extrapolations of the lunar impact record, or assumptions about the cometary mass spectrum. The results imply that the Earth would have acquired an exogenous ocean of water between ∼4.5 and ∼3.8 Gyr ago if comets comprised ≳10% by mass of the impacting population.
|Original language||English (US)|
|Number of pages||4|
|State||Published - 1987|
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