SENSITIVITY RESEARCH ON MODELS OF EARTH ENTRY AND IMPACT EFFECTS BY ASTEROIDS

Asteroid impact on Earth is one of the potential threats to human beings. Engineering models of Earth entry and impact effects by asteroids have been developed in order to estimate ground hazard by planetary defense communities nowadays. However, there are large uncertainties in input parameters of these models, which not only brings trouble to use of the model, but also greatly affects results of hazard estimate. Ranges of input parameters are analyzed, of Which baseline values are taken as maximum probability values or recommended values in literatures. Furthermore, by changing one or more input parameters based on ranges and baseline values, AICA (Asteroid Impact Consequence Analysis) code developed by authors of this paper, are used to study sensitivity of output parameters, such as energy deposition, airburst altitude, radius of 4psi overpressure and 3rd degree burn, to input parameters. The results are given for stony asteroids with diameter of 60~300~m and entry velocity of 12~40~km/s. It is indicated by results that airburst altitude of asteroid trends to decrease, with increase of size, strength at 1st breakup and mass fraction of debris cloud, and with decrease of entry velocity and ablation coefficient. Drag coefficient of asteroid and fragment, as well as strength scaling exponent, has little effect on airburst altitude and ground damage range. Radius of overpressure and thermal radiation damage generally increases with increase of size and entry velocity. If mass fraction of debris cloud is less than 50%, airburst altitude and ground damage range will fluctuate. But a large value for mass fraction of debris cloud, such as 80%, is reasonable according to analysis of many meteor events at present. Luminous efficiency only affects damage range of thermal radiation. Under the computational condition in this paper, radius of 3rd degree burn is less than that of 4-psi overpressure, indicating that the main type of ground hazard is overpressure caused by airburst.