Uncontrolled re-entries of large intact objects: how simple criteria for assessing their potential danger could be defined

In general, the dry mass of a re-entering object and the materials of which it is made are the leading indicators of the possible risks on the ground. In fact, more mass and fragments are able to survive, the higher will be the corresponding casualty expectancy due to kinetic impact. However, in some specific cases, the risk coming from purely mechanical impacts may be far exceeded by the toxicity of chemical or radioactive substances carried on board an possibly able to be released on the ground. In this presentation, the relevance of some past uncontrolled re-entries of sizable space objects on the basis of the ISTI-CNR classification is outlined and discussed.