Microparticle Collection Experiments during the 1955 Orionid and Leonid Meteor Showers

Results are presented from two microparticle collection experiments carried out in 1966 during meteor showers. NASA-Ames Research Center's Luster instrument was launched with an Aerobee 150 sounding rocket from White Sands Missile Range at 1520 UT, October 22, 1966, during the Orionid meteor shower. The Luster instrument exposed sampling surfaces for 204 seconds between the altitudes of 77 and 149 km. The ALARR (air launched-air recovered rocket) instrument was flown over the White Sands Missile Range by the U.S. Air Force at 2015 UT, November 17, 1966, during the Leonid meteor shower. Sampling surfaces were supplied to the U.S. Air Force and exposed for 92 sec between the altitudes of 85 and 97 km. Particles in the 0.1 to 1 µ size range were located with an electron microscope. Particles in the 5 to 100 µ size range were located with an optical microsrope. No collection of particles in either size range was detected above the background contamination levels for either flight. Particles from the Luster flight were analyzed for elemental composition using an electron microprobe. Certain elemental groups [(Ni); (Fe and Si); (Fe); and (Ca, Ba or K)] were found in increased concentrations on flight surfaces in comparison with similar surfaces that were not exposed. These results are in general agreement with the results of the 1965 Luster flight into the Leonid meteor shower. If the increased concentrations of particles with certain compositions reflect true collections, then either the Orionid and the Leonid meteor showers are similar in composition, or a collection of sporadic meteoric material has been made.