Electromagnetic properties of impact-generated plasma, vapor and debris

Plasma, vapor and debris associated with an impact or explosive event have been demonstrated in the laboratory to produce radiofrequency and optical e lectromagnetic emissions that can be diagnostic of the event. Such effects could potentially interfere with communications or remote sensing equipment if an impact occurred, for example, on a satellite. More seriously, impact generated plasma could end the life of a satellite by mechanisms that are not well understood and not normally taken into account in satellite design . For example, arc/discharge phenomena resulting from highly conductive pla sma acting as a current path across normally shielded circuits may have con tributed to the loss of the Olympus experimental communications satellite o n August 11, 1993. The possibility of significant storm activity during the Leonid meteor showers of November 1998, 1999 and 2000 (impact velocity, 72 km/s) has heightened awareness of potential vulnerabilities from hypervelo city electromagnetic effects to orbital assets. The concern is justified. T he amount of plasma, electrostatic charge and the magnitude of the resultin g currents and electric fields scale nearly as the cube of the impact veloc ity (proportional to(v)(2,6)). Even for microscopic Leonid impacts, the amo unt of plasma approaches levels that could be dangerous to spacecraft elect ronics. The degree of charge separation that occurs during hypervelocity im pacts scales linearly with impactor mass. The resulting magnetic fields inc rease linearly with impactor radius and could play a significant role in ou r understanding of the paleomagnetism of planetary surfaces. (C) 1999 Elsev ier Science Ltd. All rights reserved.