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EP: Extraterrestrische Physik

EP 11: Gas, Staub und kleine Körper

EP 11.3: Talk

Friday, March 24, 2000, 12:15–12:30, N3110

Electric Charges, Electromagnetic Emission and Corona Discharges during Low Velocity Impacts — •Friedemann Freund¹ and Pascal C. Lee² — ¹SETI Institute/NASA Ames Reseach Center — ²NRC / NASA Ames Research Center

Laboratory gun experiments show that positive charges are generated in common igneous rocks impacted under a range of velocity regimes. Both at low velocity (100 m/sec) in the absence of a shock wave, and at high-velocity (1.5 km/sec) in the wake of internal shock waves, charges are observed to spread from the impact point through the rock volume. Charge propagation is accompanied by low frequency electromagnetic emission. Transient surface potentials resulting from charge build-up have been observed in the +0.5 to +1 V range. Charge propagation can also produce corona discharges from edges and corners. Such electrophysical phenomena could have important implications for the evolution of small bodies such as asteroids and early planetesimals. For instance, impact-induced corona discharges might have contributed to regolith consolidation on small, low- gravity objects. The study of impact-induced electrophysical phenomena are offering many new insights into the evolution of planetary surfaces.