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. Thi s indicates an influx of particles that is well above the heliocentric parabolic limit for closed orbits. The evidence for these extremely h igh Earth-encounter speeds comes from meteor echo timing and ionizatio n height characteristics. It is shown that aliasing associated with a finite radar sampling rate imposes an upper limit on the atmospheric s peeds available from echo diffraction characteristics. The possibility of an interstellar source as evidenced by the heliocentric radiant di stribution is discussed.