Laboratory and computer simulations of the global magnetosheric effects caused by anti-asteroidal explosions at near-Earth space

Up today the only probable scenario to mitigate a collision with new Near-Earth Objects of 1 km-size consists of theirs deflection by a very high-energy explosion (100-1000 MT of TNT) at the distances from the Earth comparable with the sun-ward scale of magnetosphere. Since magnetosphere own magnetic energy is not more than 250MT, it means that a giant plasma cloud (of energy similar to100MT) released by such explosion may cause global and even catastrophic geoplasma disturbances. The magnitude and nature of them can't be predicted by existing 3D numerical codes in a full measure. The necessary data about the after-effects can be obtained mainly in simulation experiments on expansion of Laser-produced Plasma Clouds inside of laboratory model of magnetosphere. Since in case of near-Earth explosion plasma expansion will be sub-Alfvenic, as the first step the dynamic of plasma clouds in a vacuum dipole magnetic field have been studied experimentally(1) and the results obtained have been compared with MHD analytical model(3) and 3D/PIC-numerical simulation(2). A preliminary analysis shows that initial evolution of plasma clouds can be satisfactorily described by MHD-based similarity criterion and scales. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.