Radar measurements of very high velocity meteors with AMOR

The Christchurch (New Zealand) meteor radar AMOR has yielded about 1% of meteoroids having an atmospheric speed in excess of 100 km s-1. This indicates an influx of particles that is well above the heliocentric parabolic limit for closed orbits. The evidence for these extremely high Earth-encounter speeds comes from meteor echo timing and ionization height characteristics. It is shown that aliasing associated with a finite radar sampling rate imposes an upper limit on the atmospheric speeds available from echo diffraction characteristics. The possibility of an interstellar source as evidenced by the heliocentric radiant distribution is discussed.