The Davy Crater Chain: Implications for tidal disruption in the Earth‐Moon System and elsewhere

Abstract

Linear crater chains on Ganymede and Callisto apparently provide an impact record of tidally disrupted bodies, like Comet Shoemaker‐Levy 9, at Jupiter. We propose that the Davy crater chain on the Earth's Moon records a similar tidal disruption event in the Earth‐Moon system. Most lunar crater chains result from either volcanism or secondary impacts, but the Davy chain differs in setting and appearance from these crater chains and instead shows morphologic similarities to the Jovian crater chains. While the Davy chain is much smaller than the Jovian crater chains, tidal disruption models indicate that this smaller size is consistent with the Earth's lower mass. The disruption models also indicate that most Earth‐crossing comets and asteroids are moving too fast for fragment dispersion before impact to produce the observed crater chain length. Thus, the Davy and Jovian crater chains apparently result from bodies with different orbital characteristics. In addition, the limited dispersion of high velocity fragments at the Moon suggests that crater chains may not form for all disruption events or on all planetary satellites. Based on modeled fragment dispersions elsewhere in the solar system, we suggest that similar crater chains may be present on Iapetus, and possibly on Titan, Titania or Oberon.