Article from Meteorite Quarterly: November 2006, 12(4), 17 – 19 The Problem of Ice Meteorites

Nothing stimulates the imagination more than the mysterious, and one stimulating mystery, concerning the fall of large blocks of ice to the Earth’s surface, has recently been reviewed in this magazine by Saul (2006). The point that I would particularly like to pick-up on, however, relates to Saul’s suggestion that, “it now seems more prudent to assume that ice meteorites do exist than that they do not”. That large blocks of ice fall to the ground is evident enough; they are observed to fall and they are collected, but the central question here is did they enter the Earth’s atmosphere from interplanetary space? Indeed, it is this latter requirement that must be satisfied, by definition, for such ice remnants to be considered meteorites. In addition, accepting for the moment that ice meteorites might fall to Earth, the question of their origin must also be addressed – literally, where are the ice fragments from. It is certainly true that the solar system contains numerous bodies that have water-ice as a major compositional component. In principle, therefore, one would expect ice meteoroids to exist simply because of the on-going collisional evolution of objects within the solar system. Indeed, it is a certainty that ice-meteoroids exist. The recent outburst of comet 73P / Schwassmann